CZ316692A3 - Mono-, bis- or tris(substituted 2,2'-bipyridine) complexes of iron, ruthenium, osmium or vanadium and process for preparing thereof - Google Patents

Description

Mono-, bis- or iron complexes, preparations.

. _{Ί <ΐ} __f tris (substituted 2,2'-bipyridine) ruthenium, osmium and vanadium and method for their

Technical field

The invention relates to a novel group of mono-, bis- or tris (substituted 2,2'-bipyridine) iron, ruthenium, osmium or vanadium complex compounds in which said bipyridine is substituted with at least one electron donor group. The invention also relates to a process for the preparation of these novel complex compounds. The compounds can be used as mediators for amperometric sensors and for other purposes.

BACKGROUND OF THE INVENTION

The determination of the concentration of certain components, and particularly glucose, in biological fluids has recently been greatly improved by using amperometric sensors. These sensors use an electrode coated with a mediator and an enzyme that is specifically designed for said component, for example for the determination of glucose, that is glucose oxidase. These sensors thus allow the measurement of the electron transfer that is conducted between the enzyme and the electrode by means of an intermediate mediator, the electron transfer being proportional to the amount of component present in the biological fluid to be tested.

The quality of these sensors, i.e. their accuracy, the reproducibility of the results obtained by several sensors from the same series, their reliability and the speed of their response time largely depend on the mediator used.

Among these known mediators of the prior art, for example from U.S. Pat.

No. 545,382 (Genetics International), which may include polyviologene, chloranil, fluoranil or ferrocene.

However, these prior art mediators have a number of drawbacks.

Since these mediators do not conduct electrons between the enzyme and the electrode fast enough, the sensor response time is somewhat long. In addition, some of these mediators, such as ferrocene, are relatively volatile and unstable, especially when exposed to light, so that these sensors must be stored under stricter light and temperature conditions. Furthermore, some mediators, especially ferrocene, are degraded in water by hydrolysis, which is a disadvantage when these sensors are used in blood.

Finally, oxygen is competing with some mediators, so the results of blood glucose concentration measurements vary according to the amount of oxygen present in the blood. This may be a disadvantage depending on whether venous or arterial blood is analyzed.

SUMMARY OF THE INVENTION

From the foregoing, it is clear that there is a need in the art to find and prepare mediators that are fast, stable, and which would not have problems in influencing the results due to a competitive reaction with oxygen.

Research in this field has led to the discovery of a novel class of mediators according to the invention based on mono-, bis- or tris (substituted 2,2'-bipyridine) novel iron, ruthenium, osmium and vanadium complexes in which said bipyridine is substituted with at least one electron a donor group, and a process for preparing these substances.

The novel group of complex compounds of the present invention is not only of theoretical interest, but above all, in addition to all other properties for which they can be used for many different other practical applications, as a group of complex compounds with good mediator properties.

The invention will be explained in more detail below by a detailed description of a group of complex compounds according to the invention and a detailed description of all embodiments of the processes for the preparation of these compounds.

This new group of mono-, bis- or tris (substituted 2,2'-bipyridine) metal complex M compounds can be represented by the following general formula I:

(I) in which:

M iron, osmium, ruthenium or vanadium,

L is bipyridine which is substituted with at least one electron donor group which confers to the complex compound the oxidation-reduction properties required for mediator function, which electron donor group is preferably a hydroxy, alkoxy or aryloxy group or a primary, secondary or a tertiary amine group,

L ₁ , L ₂ , L g and L ₄ are ligands that form a coordination complex with iron, osmium, ruthenium and vanadium.

In this context, it should be noted that in these complex compounds, L is preferably bipyridine disubstituted at the 4,4'-positions, and in particular, 4,4'-dihydroxy-2,2 'are preferred ligands. -bipyridine, 4,4'-dimethoxy-2,2'-bipyridine and 4,4'-bis (N, N-ethylamino) -2,2'-bipyridine, also known as 4,4'-bis (Ν (Ν-diethylamino) -2,2'-bipyridine. These complex compounds have the following general formulas II, III and IV:

N

OH

OH

(II)

(IV) unilateral,

The ligands, L ₂ , L ₃ and L ₄ may be divalent, trivalent or quadruple, and may be combined as follows:

each of the ligands L ₂ , L ₃ and L ₄ represents a monovalent ligand, being exactly the same, partially identical or completely different from each other;

- or Lj ligands. and L ₂ together form a divalent ligand, and L ₃ and L ₄ represent the same or different ligands, each of which is a monovalent ligand;

or L ₁ and L ₂ ligands on the one hand and L ₃ and L ₄ ligands on the other hand form bivalent ligands;

or L ₁ represents a monovalent ligand and the ligands L ₂ , L ₃ and L ₄ together form a trivalent ligand;

or the ligands L ₁ , L ₂ , L ₃ and L ₄ together form a tetravalent ligand.

The group mentioned monovalent ligands which can be used according to the invention can include CN, Cl ^-, NH _2, N0 ₂ or alkyl.

The group of bidentate ligands that can be used in this invention can include ethylenediamine, 1,2-bis (2-pyridyl) ethane, oxalic acid O ^- CO-CO-O ^-, acetylacetone, CH3-CO-CH2-CO -CH 3, glycine NH 2 -CH 2 -COO ^- and preferably a bipyridine or phenanthroline group which are disubstituted by R 1 and R 2, wherein the groups R 1 and R ₂ are the same or different and each represents a hydrogen atom, NO ₂ , Cl, an alkyl group, an aryl group, a hydroxyl group, an alkoxy group, an aryloxy group, or a primary, secondary or tertiary amine group.

The trivalent ligand is preferably a tripyridine of formula V

wherein R ₃ is hydrogen or alkyl.

The trivalent ligand that is used in a preferred embodiment of the present invention is

- triethylenetetramine:

shown in the above formula in coordination with the metal M, and

- ethylenediaminediacetic acid:

also shown in coordination with metal M.

When L ₁ , and L ₂ on the one hand and L ₃ and L ₄ on the other hand form divalent ligands, and if the two divalent ligands are the same as L ligand, then a tris-complex compound of L ligand and metal is obtained M, the metal being iron, ruthenium, osmium or vanadium.

Preferably, the tris (L-ligand) complexes of the present invention are:

- tris (4,4'-dihydroxy-2,2'-bipyridine) metal M complexes,

- tris (4,4'-dimethoxy-2,2'-bipyridine) metal complexes Μ, a

- tris (4,4'-bis (Ν, N, -ethylamino) -2,2'-bipyridine) metal M complexes

When L ₁ and L ₂ together form the first divalent ligand and L ₃ and L ₄ together form the second divalent ligand and in addition only the first divalent ligand is identical to L, then bis (L ligand) is obtained a metal complex M wherein M has the same meaning as previously described.

In a preferred embodiment of the present invention said bis (ligand L) complex compounds of metal M are the following:

- metal bis (4,4'-dihydroxy-2,2'-bipyridine) mono (2,2'-bipyridine) complexes,

- metal bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'-dimethoxy-2,2'-bipyridine) complexes,

- metal bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) complexes,

- bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4-alkyl-2,2'-bipyridine) metal M complexes,

- bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4-dialkyl-2,2'-bipyridine) metal M complexes,

- metal bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,7-dihydroxy-1,10-phenanthroline) complexes,

- bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'bis (N, N-ethylamino-2,2'-bipyridine) metal M complexes,

- metal bis (4,4'-dimethoxy-2,2'-bipyridine) mono (2,2'-bipyridine) complexes,

- bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4 'dimethyl-2,2'-bipyridine) metal M complexes,

- metal bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4-alkyl-2,2'-bipyridine) complexes,

- bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'-dialkyl-2,2'-bipyridine) metal M complexes,

- metal bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,7-dihydroxy-1,10-phenanthroline) complexes,

- metal bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'-dihydroxy-2,2'-bipyridine) complexes,

- metal bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'-bis (Ν, N-ethylamino) -2,2´-bipyridine) complexes,

- metal bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono (2,2'-bipyridine) complexes,

- bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono (4,4'-dimethoxy-2,2'-bipyridine) metal M complexes,

- bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono (4,4'-dimethyl-2,2´-bipyridine) metal M complexes,

- metal bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono (4-alkyl-2,2'-bipyridine) complexes,

- bis (4,4'-bis (N, N-ethylamino) -2,2´-bipyridine) mono (4,4'-dialkyl-2,2'-bipyridine) metal M complexes,

- bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono (4,4'-dihydroxy-2,2'-bipyridine) metal M complexes,

- metal (M) bis (4,4'-bis (-, N-ethylamino) -2,2'-bipyridine) mono (4,7-dihydroxy-1, 10-phenanthroline) complexes

When the ligands and L ₂ together form the first divalent ligand and the ligands L ₃ and L ₄ together form the second divalent ligand and if in addition the first divalent ligand and the second divalent ligand differ from the ligand L, then a mono (L ligand) is obtained ) a metal complex M, wherein the metal M is iron, ruthenium, osmium or vanadium.

When said first ligand (i.e., linked ligands L 4 and L ₂ ) and said second ligand (i.e., linked ligands L ₃ and L ₄ ) are identical, the preferred mono (ligand L) complexes of the present invention are as follows: compounds:

- mono (4,4'-dihydroxy-2,2'-bipyridine) bis (4,4'-dimethyl-2,2'-bipyridine) metal M complexes,

- mono (4,4'-dihydroxy-2,2'-bipyridine) bis (2,2'-bipyridine) metal M complexes,

- mono (4,4'-dihydroxy-2,2'-bipyridine) bis (4-alkyl-2,2'-bipyridine) metal M complexes,

- mono (4,4'-dihydroxy-2,2'-bipyridine) bis (4,7-dihydroxy-1,10-phenanthroline) metal M complexes,

- mono (4,4'-dimethoxy-2,2'-bipyridine) bis (4,4'-dimethyl-2,2'-bipyridine) metal M complexes,

- mono (4,4'-dimethoxy-2,2'-bipyridine) bis (2,2'-bipyridine) metal M complexes,

- mono (4,4'-dimethoxy-2,2'-bipyridine) bis (4-alkyl-2,2'-bipyridine) metal M complexes,

- mono (4,4'-dimethoxy-2,2'-bipyridine) bis (4,7-dihydroxy-1,10-phenanthroline) metal M complexes,

- mono (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) bis (4,4'-dimethyl-2,2'-bipyridine) metal M complexes,

- mono (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) bis (2,2'-bipyridine) metal M complexes,

- mono (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) bis (4-alkyl-2,2'-bipyridine) metal M complexes,

- metal mono (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) bis (4,7-dihydroxy-1, 10-phenanthroline) complexes,

If the aforementioned first ligand (i.e., the linked ligands and L ₂ ) and said second ligand (i.e., the linked ligands L ₃ and L ₄ ) are different, the preferred mono (ligand L) complexes of the present invention are the following compounds:

- mono (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'dihydroxy-2,2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) metal complexes M.

The present invention also relates to a process for the preparation of the aforementioned complex compounds.

In particular, the present invention provides a process for preparing tris (L ligand) of metal M complexes, wherein the metal is iron, ruthenium, osmium, or vanadium. Said ligand L is a divalent ligand namely

4,4'-dimethoxy-2,2'-bipyridine ligand,

4,4'-dihydroxy-2,2'-bipyridine ligand or

4,4'-bis (N, N-ethylamino) -2,2'-bipyridine ligand.

This process comprises the following steps:

- reacting the soluble metal salt M with a substantially stoichiometric amount of ligand A in the presence of a solvent suitable for dissolving the aforementioned ligand, and then

heating the solution at reflux temperature at atmospheric pressure and near the boiling point of said solvents.

In most cases, ligand A is identical to or similar to ligand L relative to ligand L that can be converted to ligand L during the reaction. This ligand A may, for example, be of the same type as ligand L, but otherwise substituted. This example describes, for example, the procedure of Example 1 (see Example section) starting from bipyridine, which is disubstituted by two methoxy groups, to give bipyridine disubstituted by two hydroxy groups. In Example 1, as well as in Examples 5 and 11, which will follow in the Examples section, 4,4'-dimethoxy-2,2'-bipyridine is used to prepare complex compounds containing

4,4'-dihydroxy-2,2'-bipyridine, because this 4,4'-dihydroxy-2,2'-bipyridine is not commercially available due to difficulties in its preparation and costs preparation.

The nature of the soluble metal salt M varies with the above ligands. Depending on whether the metal M is iron, ruthenium, osmium or vanadium, may be that the soluble salt of ferrous chloride FeCl _2, K ₂ 0sCl ₆ RuC1 ₃ or VClg.

The present invention particularly relates to a process for preparing tris ^{(4,4-dihydroxy-1} 2,2-bipyridine) complex of the metal M, wherein this metal may be iron, ruthenium, osmium or vanadium.

In general, this procedure involves the following steps:

- reacting the soluble salt of metal M, wherein the metal is the same metal as above, with a substantially stoichiometric amount of 4,4'-dimethoxy-2,2'-bipyridine in the presence of ethylene glycol, followed by

- refluxing the solution at reflux, under nitrogen, at atmospheric pressure and at a temperature ranging from 190 ° C to

200 ° C, preferably 195 ° C.

Said soluble salts of the metal M are the same as the abovementioned salts.

Selection of the solvent (an ethylene glycol) allows to work at elevated temperatures (i.e., about 190 to about 200 ° C) while at the same temperature as above performs only cleave between OCH _3, and bipyridine without encountering another further chemical modifications.

After the OCH ₃ bond is cleaved, OH groups can form a tris (4,4'-dihydroxy-2,2'-bipyridine) metal M complex.

DETAILED DESCRIPTION OF THE INVENTION

Specific examples of the mono-, bis- or tris (substituted 2,2'-bipyridine) complex compounds of the present invention and procedures for preparing these compounds will be described below. These examples are illustrative only and not limiting.

Example 1

Preparation of tris (4,4'-dihydroxy-2,2'-bipyridine) osmium complex.

0.100 g (0.21 mmol) of K ₂ Cl _{2 g was} dissolved in 10 ml of ethylene glycol and 0.144 g (0.67 mmol) was added to the solution.

4,4'-dimethoxy-2,2'-bipyridine. The solution is heated at reflux for at least 24 hours, under a nitrogen atmosphere, at atmospheric pressure and at a temperature in the range of about 190 to about 200 ° C, preferably at 195 ° C. C. A brown-colored solution was obtained. The solution was allowed to cool to room temperature and then concentrated to half its volume. The product was precipitated as the trifluoromethanesulfonate by adding trifluoromethanesulfonic acid to the ethylene glycol solution.

The complex compound was filtered, washed with a 1: 10 v / v mixture of acetone and diethyl ether and dried under high vacuum.

In this way, a tris (4,4'-dimethoxy-2,2'-bipyridine) osmium complex was prepared having the following physicochemical properties:

- Elemental analysis:

formula 2 ^H 24 ^N 6 ° 12 ^F 6 ^OsS 2 H ₂ 0) measurements made with trifluoromethanesulfonate)

Calculated Found C 35,56% 35,75% H 2.53% 3.02% N 7.78% 7,10% ^H 2 ° 2.58% 2.58%

- Oxidation-reduction potential E ° (normal potential)

When said complex compound is dissolved in an organic solvent such as acetonitrile in the presence of 0.2 M LiClO ₄ and a potentiometric measurement is performed using a glassy carbon electrode, E ° = + 280 mV (in compared with the calomel reference electrode SCE).

In an aqueous solvent of PBS (a phosphate buffer solution containing: 100 mM sodium chloride NaCl and 10 mM sodium dihydrogen phosphate NaH ₂ PO ₄ , first adjusting the pH to 1 and then to pH = 13), the following results are obtained using a carbon electrode :

pH = 1; E ° = + 150mV (SCE)

pH = 13; E ° = -1V (SCE).

- NMR (nuclear magnetic resonance).

No OCH ₃ peaks at 4.1 ppm were detected in the sample dissolved in CD ₂ Cl ₂ , indicating that these groups were completely hydrolyzed to form OH groups. Aromatic proton peaks can be observed in the range of 6.8 ppm to 8 ppm compared to the tetraraethylsilane standard.

- Absorption spectra values in ultraviolet and visible radiation.

wavelength λ max (nm)

239

269

300

357

385

474

512

654

712 extinction coefficient ^ε (M ~ ^ cm ~ · '·

13850

13300

12600

11500

10858

7430

6240

1475

1156

When L is ligand 4,4'-dimethoxy-2,2'-bipyridine, the process for preparing this tris (L ligand) of the metal M complex comprises the following steps:

- reacting the soluble metal salt M with a substantially stoichiometric amount of 4,4'-dimethoxy-2,2'-bipyridine in the presence of methanol, dimethylformamide (DMF) and / or water, followed by:

heating the solution under reflux (under reflux), under a nitrogen atmosphere, at atmospheric pressure and at a temperature ranging from about 70 to about 80 ° C.

The choice of the solvent (i.e., methanol, DMF and / or water) used is important since it allows, in contrast to the procedure of Example 1, to operate at relatively low temperatures (in the range of about 70 to about 80 ° C) and thereby avoid cleavage of the bond between the OCH ₃ group and bipyridine. In addition, these solvents make it possible to reduce metal M from oxidation state +3 to oxidation state +2 in the case of ruthenium, from oxidation state +4 to oxidation state +2 in the case of osmium and from oxidation state +3 to oxidation state +2 in the case of vanadium. Iron does not change its oxidation state and always remains in the +2 oxidation state. It should further be noted that, in the case of vanadium, it is necessary to use additional reactants in order to achieve an oxidation state of 0.

A specific example illustrating the procedure for obtaining one of these complexes is given in the following example.

Example 2

Preparation of tris (4,4'-dimethoxy-2,2'-bipyridine) osmium complex.

0.100 g (0.21 mmol) of K ₂ Cl _{2 was} dissolved in a mixture containing 5 ml of water, 5 ml of methanol and 5 ml of dimethylformamide (DMF). To this solution was added 0.144 g (0.67 mmol)

4,4'-dimethoxy-2,2'-bipyridine, and the mixture is then refluxed for at least 60 hours under a nitrogen atmosphere, at atmospheric pressure and at a temperature in the range of about 70 ° C. to about 80 ° C.

After this treatment, a brown coloring of this solution appeared. After cooling to room temperature, the solution was filtered and the solvent was removed completely by rotary evaporation. A minimum amount of ethanol was added to dissolve the product, and the solution was filtered to remove insoluble potassium chloride. The product was precipitated as trifluoromethanesulfonate by addition of a dilute trifluoromethanesulfonic acid solution. The complex was filtered, washed with a 1: 10 by volume mixture of acetone and diethyl ether, and dried under high vacuum.

In this way, tris (4,4'-dimethoxy-2,2'-bipyridine) osmium complex was obtained with the following physicochemical characteristics:

- Elemental Analysis Formula C ₃₈ H ₃₆ N ₆ O ₁₂ F ₆ OsS2 (1.11 H ₂ 0 measurements taken with trifluoromethanesulfonate)

Calculated C 39,45% H 3.33% N 7.26% ^H 2 ° 1,73%

Found 39.13%

3.27% 7.41% 1.73%

- Oxidation-reduction potential

E ° (normal potential)

When the complex compound is dissolved in an organic solvent such as acetonitrile in the presence of 0.2 M LiCl ₄ and a potentiometric measurement is performed using a glassy carbon electrode, E 0 = + 325 mV (in compared with the calomel reference electrode SCE).

In an aqueous solvent, PBS (a phosphate buffer solution containing: 100 mM NaCl and 10 mM NaH ₂ PO ₄ , adjusting the pH to 7.4) is obtained with a carbon electrode

- 19 the following result:

E ° = +225 mV.

- NMR (nuclear magnetic resonance)

Dissolution of the sample in CD ₂ Cl ₂ revealed an OCH-β peak at 4.1 ppm and an aromatic proton peak between 6.8 ppm and 8.0 ppm compared to the tetramethylsilane standard.

- Absorption spectra values in ultraviolet and visible radiation.

wavelength extinction coefficient

max (nm) ^ε (M ¹ cm ^- 228 80800 271 70800 333 22236 385 16012 397 15296 470 12564 510 11404 630 4820 696 4012

The general procedure for preparing the tris (4,4'-bis (N, N-ethylamino) 2,2'-bipyridine) metal M complex, which metal is iron, ruthenium, osmium or vanadium, will be described below.

The above reaction process comprises the following steps:

- reacting the soluble metal salt M with a substantially stoichiometric amount of 4,4'-bis (Ν, N-ethylamino) -2,2 'bipyridine in the presence of ethylene glycol, followed by

heating the solution thus obtained at reflux, under a nitrogen atmosphere, at atmospheric pressure and at a temperature in the range of about 190 to about 200 ° C, preferably 195 ° C.

The soluble metal salt M thus used is identical to the above-mentioned soluble metal salt M.

A specific example illustrating the process for preparing one of these complexes is given in the following example.

Example 3

Preparation of tris (N, N-ethylamino-2,2'-bipyridine) osmium complex.

0.100 g (0.21 mmol) of K ₂ Cl _{2 was} dissolved in 10 ml of ethylene glycol, and 0.193 g (0.64 mmol) of 4,4'- was added to the solution. bis (Ν, N-ethylamino) -2,2'-bipyridine. The solution was heated at reflux for at least 10 hours under nitrogen atmosphere at atmospheric pressure and at a temperature in the range of about 190 ° C to 200 ° C, preferably at room temperature. uses 195 ° C. The solution was allowed to cool to room temperature, filtered, and concentrated to half its volume. The product was precipitated as the trifluoromethanesulfonate by addition of trifluoromethanesulfonic acid.

The complex was filtered, washed with a 1: 10 by volume mixture of acetone and diethyl ether and dried under high vacuum.

The present invention also relates to a process for preparing a bis (ligand L) mono (ligand B) metal M complex, wherein the metal is iron, osmium, ruthenium or vanadium, the ligand L being 4,4'-dimethoxy-2,2'-bipyridine; 4,4'-dihydroxy-2,2'-bipyridine or 4,4'-bis (N, N-ethylamino) -2,2'-bipyridine, and ligand B is a divalent ligand, such as those mentioned in the introduction of the description of the invention.

One possible form of this complex, i.e. the bis (ligand L) C ₁₂ complex of the above-mentioned metal M, and the process for preparing the complex will be described below.

It should be noted at this point that it is understood that the bis (ligand L) C ₁₂ complex of the above metal M used in the preparation of said bis (ligand L) mono (ligand B) complex of said metal M is not necessarily prepared as described herein.

A process for the preparation of the bis (ligand L) C ₁₂ metal complex M, wherein the metal is iron, osmium, ruthenium or vanadium and said ligand L is 4,4'-dimethoxy-2,2'-bipyridine or 4,4'-dihydroxy-2 , 2'-bipyridine generally comprises the following steps:

- reacting the soluble salt of the metal M (wherein the metal is the same metal M as mentioned above) with a substantially stoichiometric amount of 4,4'-dimethoxy-2,2'-bipyridine in the presence of a suitable solvent mixture, in particular the mixture is for example water and methanol for the first ligand L and ethylene glycol for the second ligand, followed by

heating the solution under reflux (or reflux) under a nitrogen atmosphere, at atmospheric pressure and, for example, at a temperature in the range of about 70 to about 80 ° C when water and methanol are used as the solvent, or from 190 to 200 ° C when ethylene glycol is used as the solvent.

Preparation of the same complex, wherein the ligand L is 4,4'-bis (Ν, N-ethylamino) -2,2-bipyridine ^1, generally comprises the following steps:

- reacting the soluble salt of the metal M, the metal M being the same as above, with a substantially stoichiometric amount of 4,4'-bis (N, N-ethylamino) 2,2'-bipyridine in the presence of dimethylformamide (DMF), followed by

heating the solution under reflux (or reflux) under a nitrogen atmosphere, at atmospheric pressure and at a temperature in the range of from 150 to 155 ° C.

In these two cases, the soluble salts of the metal M are the same salts as mentioned above.

In the following, three specific examples of the preparation of these compounds will be given.

Example 4

Preparation of the bis (4,4'-dimethoxy-2,2'-bipyridine) osmium complex.

0.100 g (0.21 mmol) of K ₂ OsClg was dissolved in a mixture containing 5 ml of water and 5 ml of methanol, and 0.90 g (0.42 mmol) was added to the solution. Of 4,4'-dimethoxy-2,2'-bipyridine. The solution was heated under reflux (reflux) for at least 2 hours, under a nitrogen atmosphere, at atmospheric pressure and at a temperature ranging from 70 to 80 ° C. The color of the solution turned dark purple. The solution was allowed to cool to room temperature and the solvent was removed completely by rotary evaporation. Then 10 milliliters of water was added to the solution. The thus obtained bis (4,4'-dimethoxy-2,2'-bipyridine) C ₁₂ osmium complex was collected by filtration and washed with water followed by a 1: 6 mixture of acetone and diethyl ether to eliminate unreacted ligand residues. . Finally, the complex was dried under high vacuum.

Results of elementary analysis of the following text.

are listed in

Elemental analysis: Formula ^C 24 ^H 24 ^N 4 ° 4 ^OsCl 2

Calculated C 41,56% H 3.49% N 8.08%

Found 42.02%

3.73% 8.45%.

Example 5

Procedure for preparing bis (4,4'-dihydroxy-2,2'-bipyridine) Cl ₂ osmium complex.

0.100 g (0.21 mmol) of K ₂ Cl _{2 was} dissolved in a mixture containing 2 ml of water and 10 ml of ethylene glycol, and 0.090 g (0.42 mmol) was added to the solution. 4,4'-dimethoxy-2,2'-bipyridine. The solution was heated to reflux for at least 16 hours using a nitrogen atmosphere, atmospheric pressure and a temperature of 190 to 200 ° C, preferably 195 ° C. The color of the solution turned dark purple. The solution was allowed to cool to room temperature and then concentrated by rotary evaporation. The product was precipitated by the addition of acetone.

The resulting precipitate was collected by filtration, washed further with acetone and ether, and then dried under high vacuum.

This bis (4,4'-dihydroxy-2,2'-bipyridine) C ₁₂ osmium complex, prepared as described above, was in the form of blue crystals. The yield was 80 to 90%.

In the two procedures of Examples 4 and 5, the choice of solvent and reaction temperature was carried out according to the same principle as above.

Example 6

Procedure for preparing bis (4,4'-bis (N, N-ethylamino) -2,2'bipyridine) C ₁₂ osmium complex.

0.100 g (0.21 mmol) of K ₂ OsClg was dissolved in 10 ml dimethylformamide (DMF) and 0.125 g (0.42 mmol) was added to the solution. 1'-bis (N, N-ethylamino) -2,2'-bipyridine.

The solution was heated to reflux for at least 4 hours using a nitrogen atmosphere, atmospheric pressure, and temperature ranging from 150 to 155 ° C. The solution was allowed to cool to room temperature and the solvent was completely removed by rotary evaporation. Then 10 ml of cold water was added to the solution and the obtained bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) Cl ₂ osmium complex (which was poorly soluble) was then isolated by filtration. The complex was washed with water and then with a 1: 6 v / v mixture of acetone and diethyl ether to remove residual trace amounts of unreacted ligands and finally dried under high vacuum.

The procedure for preparing the bis (ligand L) mono (ligand B) metal complex M mentioned above will be described below.

This procedure includes the following steps:

reacting the bis (ligand L) C ₁₂ complex of said metal M with a substantially stoichiometric amount of ligand B in the presence of a suitable solvent or solvents to dissolve the complex and ligand B, followed by

heating the solution thus obtained under reflux (reflux) under a nitrogen atmosphere, at atmospheric pressure and at a temperature in the vicinity of the boiling point of the solvents used.

As mentioned above, when said ligand B is 4,4 ' -dihydroxy-2,2 ' -bipyridine, the chlorinated complex preferably reacts with 4,4 ' -dimethoxy-2,2 ' -bipyridine since this product is readily available on the market.

The following are three specific examples of how to perform this procedure.

Example 7

Preparation of the bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) osmium complex.

In the process of this example, 0.05 g (0.07 mmol) of bis (4,4'-dimethoxy-2,2'-bipyridine) osmium complex C1 ₂ was reacted with 0.017 g (0.09 % of 4,4'-dimethyl-2,2'-bipyridine in the presence of a mixture containing 10 ml of dimethylformamide (DMF), 10 ml of water and 10 ml of methanol. The mixture was heated at reflux for at least 40 hours under a nitrogen atmosphere, at atmospheric pressure and at a temperature ranging from 70 to 80 ° C. Finally, the reaction mixture was allowed to cool to room temperature, filtered and the solvent was removed completely by rotary evaporation. The product was dissolved in a minimum of ethanol and then precipitated as the trifluoromethanesulfonate by addition of trifluoromethanesulfonic acid. Finally, the precipitate thus obtained was filtered, washed with a 1: 6 by volume mixture of acetone and diethyl ether, and then dried under high vacuum.

- Elemental analysis Formula C ₃₈ H _3g NgO ₁₀ F ₆ OsS ₂ (0.90 H ₂ 0) measurement performed with trifluoromethanesulfonate)

C Calculated 40,71% H 3,40% N 7.5% F 10,17% h ₂ ° 1,45%

Found 41.03%

3.46% 7.58%

10.24% 1.44%

- Oxidation-reduction potential

E ° (normal potential)

When the complex compound is dissolved in an organic solvent such as acetonitrile in the presence of 0.2 M LiClO ₄ and a potentiometric measurement is performed using a glassy carbon electrode, E ° = + 450 mV (in compared with the calomel reference electrode SCE). In phosphate buffer PBS (a solution containing: 100 mM sodium chloride NaCl and 10 mM sodium dihydrogen phosphate NaH ₂ PO ₄ , adjusting the pH to 7.4) using a carbon electrode, the following result is obtained: E ° = +340 mV .

- NMR (nuclear magnetic resonance)

Dissolution of the sample in CD ₂ C1 ₂ revealed an OCH ₃ peak at 4.1 ppm and a CH ₃ peak at 2.65 ppm as well as aromatic proton peaks between 6.8 ppm and 8.0 ppm compared to the tetramethylsilane standard .

- Absorption spectra of the radiation region.

wavelength λ max (nm)

216

290

336

378

462

494

628

674 in ultraviolet and in visible extinction coefficient £ (M ^-1 cm ^-1 )

108000

62000

15520

14580

13528

13376

6920 6540.

Example 8

Preparation of the bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) osmium complex.

In this example, 0.05 g (equivalent to 0.07 mmol) of bis (4,4'-dihydroxy-2,2'-bipyridine) Cl ₂ osmium complex was reacted with 0.017 g (0.09) % of 4,4'-dimethyl-2,2'-bipyridine in 10 ml of ethylene glycol, and the mixture was heated at reflux for at least 4 hours under a nitrogen atmosphere, at atmospheric pressure and at room temperature. at a temperature in the range of from 190 to 200 ° C, with a temperature of 195 ° C being preferred. The color of the reaction mixture turned brown. The reaction mixture was cooled to room temperature and concentrated to half volume. The product was precipitated as trifluoromethanesulfonate by addition of dilute trifluoromethanesulfonic acid to this ethylene glycol solution. The thus obtained bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) osmium complex was then filtered, washed with a 1: 10 by volume mixture of acetone and diethyl ether. and then dried under high vacuum.

Example 9

Preparation of the osmium bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) complex.

In the process of this example, 0.05 mg (corresponding to 0.058 mmol) of bis (4,4'-bis (Ν, Nethylamino) -2,2'-bipyridine) C ₁₂ osmium complex was reacted with 0.014 g (which equivalent to 0,07 mmol)

4,4'-dimethyl-2,2'-bipyridine in 10 ml of ethylene glycol, and the solution is heated under reflux (reflux) for at least 6 hours under a nitrogen atmosphere, at atmospheric pressure and at a temperature ranging from 190 DEG-200 DEG C., preferably 195 DEG C. The reaction mixture was cooled to room temperature and filtered, and the solution was concentrated in half. The product thus obtained was precipitated as the trifluoromethanesulfonate by addition of trifluoromethanesulfonic acid. The precipitate was precipitated as trifluoromethanesulfonate by addition of trifluoromethanesulfonic acid. The precipitate was filtered, washed with a 1: 6 v / v mixture of acetone and diethyl ether, and then dried under high vacuum.

The processes for the preparation of the complex compounds described in Examples 7, 8 and 9 above for osmium can be carried out in the same manner when using iron, ruthenium and vanadium.

The present invention also provides a process for the preparation of mono (ligand L) bis (ligand B) metal M complexes, wherein the metal M is iron, osmium, ruthenium or vanadium. As mentioned above, said ligand L is 4,4'-dimethoxy-2,2'bipyridine; 4,4'-dihydroxy-2,2'-bipyridine or 4,4'-bis (N, N-ethylamino) -2,2'-bipyridine and ligand B is one of the divalent ligands mentioned at the beginning of the disclosure.

This procedure includes the following steps:

- reacting the bis (ligand B) C ₁₂ complex of said metal M with ligand A in the presence of suitable solvents to dissolve the complex and ligand A, said ligand

A is selected in such a way that it can be transformed into L ligand during the reaction, and

heating the solution under reflux (reflux), under a nitrogen atmosphere, at atmospheric pressure and at a temperature close to the boiling point of said solvents.

As can be seen from the above, ligand A used is generally the same as or similar to ligand L, with only different substituents.

This case will be illustrated in the following example 11.

The other three examples of a specific embodiment illustrate the preparation process described above.

Example 10

Preparation of the mono (4,4'-dimethoxy-2,2'-bipyridine) bis (4,4'-dimethyl-2,2'-bipyridine) osmium complex.

In the process of this example, 0.05 g (0.08 mmol) of bis (4,4'-dimethyl2,2'-bipyridine) osmium complex C1 _2, which was prepared by known procedures, reacted with 0.022 grams (1.0 mmol) of 4,4'-dimethoxy-2,2-bipyridine ¹ in a mixture of 10 ml dimethylformamide (DMF), 10 ml of water and 10 ml of methanol. The solution was heated to reflux using a nitrogen atmosphere, atmospheric pressure and temperature ranging from 70 to 80 ° C. The reaction mixture was cooled to room temperature, filtered and the solvent was completely removed by rotary evaporation.

The product was dissolved in a minimum of ethanol and the product was precipitated as the trifluoromethanesulfonate by addition of trifluoromethanesulfonic acid. The precipitated complex compound was filtered with a 1: 6 v / v mixture of acetone and diethyl ether and dried under high vacuum.

The complex compound thus prepared had the following physicochemical properties.

- Oxidation-reduction potential E ° (normal potential)

When said complex compound is dissolved in an organic solvent such as acetonitrile in the presence of a salt of 0.2 M LiClO ₄ and a potentiometric measurement is performed using a glassy carbon electrode, E ° = + 500 mV (compared to SCE calomel reference electrode).

In phosphate buffer PBS (a solution containing:

100 mM sodium chloride NaCl and 10 mM sodium dihydrogen phosphate NaH ₂ PO ₄ , adjusting the pH to 7.4), using a glassy carbon electrode, gives the following result:

E ° = +390 mV (SCE reference calomel electrode).

- Absorption spectra values in ultraviolet and visible radiation.

wavelength λmax (nm)

222

290

340

380

452

498

624

684 extinction coefficient £ (M ^-1 cm ¹ )

70248

61806

13919

13884

12113

12119

4763

4061

Example 11

Preparation of the mono (4,4'-dihydroxy-2,2'-bipyridine) bis (4,4'-dimethyl-2,2'-bipyridine) osmium complex.

The procedure of Example 10 was followed except that 0.05 g (corresponding to 0.08 mmol) of bis (4,4'-dimethyl-2,2'-bipyridine) was reacted. ) Cl ₂ of osmium complex with 0.0195 grams (corresponding to 0.09 mmol)

4,4'-dimethoxy-2,2'-bipyridine in 10 milliliters of ethylene glycol, the reaction mixture thus obtained was heated under reflux (reflux) for at least 16 hours under a nitrogen atmosphere at atmospheric pressure and at a temperature ranging in the range of 190 to 200 ° C, with a temperature of 195 ° C being preferred.

Example 12

Preparation of the osmium mono (4,4'-bis (Ν, N-ethylamino) 2,2'-bipyridine) bis (4,4'-dimethyl-2,2'-bipyridine) complex.

0.05 g (corresponding to 0.08 mmol) of bis (4,4'-dimethyl-2,2 'bipyridine) C ₁₂ osmium complex, which is generally known, is reacted with 0.026 g (corresponding to 0.08 mmol) of 4,4'-bis (bis, N-ethylamino) 2,2'-bipyridine in 10 ml of ethylene glycol. The solution was heated at reflux for at least 6 hours under a nitrogen atmosphere, at atmospheric pressure and at a temperature in the range of 190 to 200 ° C, preferably at 195 ° C. The reaction mixture was cooled to room temperature, filtered and the solvent was removed while concentrating the solution to half its original volume. The product obtained was precipitated as the trifluoromethanesulfonate by addition of dilute trifluoromethanesulfonic acid. The precipitate thus obtained was filtered, washed with a 1: 6 by volume mixture of acetone and diethyl ether, and then dried under high vacuum.

These specific preparation procedures of Examples 10, 11 and 12 for osmium complexes are generally applicable and generalized to iron, ruthenium and vanadium.

In Examples 1-3 and 7-12, the final product was isolated by the addition of trifluoromethanesulfonic acid. However, it should be noted that it is of course possible to obtain the product in the form of other salts if other suitable substances for the final precipitation are chosen. For example, hexafluorophosphates can be obtained by the addition of potassium hexafluorophosphate. In the case of osmium and when using Os 2 Cl 2 as the starting material, the chlorides can be obtained with the addition of diethyl ether.

Example 13

Preparation of the tris (4,4'-diamino-2,2'-bipyridine) ruthenium complex.

In this example, 0.1 grams (equivalent to 0.38 mmol) was first dissolved.

4,4'-diamino-2,2'-bipyridine. The solution was heated at reflux for at least 4 hours using a nitrogen atmosphere, atmospheric pressure and temperature ranging from 190 to 200 ° C, preferably 195 ° C. After cooling the solution to room temperature, 5 ml of acetone and 20 ml of diethyl ether were added. The ether was then separated and removed. Then, 20 ml of ether was added again and work-up continued until a complex precipitate had formed. The complex was then collected by filtration, washed with ether and dried under high vacuum.

- Oxidation-reduction potential E ° (normal potential)

When the complex compound is dissolved in an organic solvent such as acetonitrile in the presence of 0.2 M LiCl ₄ and a potentiometric measurement is performed using a glassy carbon electrode, E ° = + 450 mV ( compared to the calomel reference electrode SCE). In phosphate buffer PBS (a solution containing: 100 mM sodium chloride NaCl and 10 mM sodium dihydrogen phosphate NaH ₂ PO ₄ , adjusting the pH to 7.4) using a glassy carbon electrode, the following result is obtained:

E ° = +170 mV (SCE reference calomel electrode).

- Absorption spectra values in ultraviolet and visible radiation.

wavelength λ max (nm) 354 394

472

514 extinction coefficient Č (M ^-1 cm ^-1 )

17655

11988

8064 9444.

Example 14

Preparation of the tris (4,4'-diamino-2,2'-bipyridine) iron complex.

In the process of this example was 0.1 g (corresponding to 0.50 mmol) of ferrous chloride tetrahydrate FeCl _second 4H ₂ O dissolved in 10 milliliters of water. The solution was added dropwise to 10 ml of a boiling solution containing 0.29 g (1.55 mmol) of 4,4'-diamino-2,2'-bipyridine. The color of the solution turned violet-red. The reaction mixture was cooled to room temperature and 20 ml of diethyl ether was added to precipitate the desired complex compound. The complex was collected by filtration, washed with a 1: 6 v / v mixture of acetone and diethyl ether, and then dried under high vacuum.

- Oxidation-reduction potential E ° (normal potential)

When the complex compound is dissolved in an organic solvent, such as acetonitrile, in the presence of 0.2 M LiCl ₄ and a potentiometric measurement is performed using a glassy carbon electrode, E ° = + 225 mV ( compared to the calomel reference electrode SCE). In phosphate buffer PBS (a solution containing: 100 mM sodium chloride NaCl and 10 mM sodium dihydrogen phosphate NaH ₂ PO ₄ , adjusting the pH to 7.4) using a glassy carbon electrode, the following result is obtained:

E ° = +70 mV (SCE reference calomel electrode).

- Absorption spectra values in ultraviolet and visible radiation.

Claims (26)

Mono-, bis- or tris (substituted 2,2'-bipyridine) metal M complexes of the general formula I- ₂ (m) in which: M iron, ruthenium, osmium or vanadium, L represents 2,2'-bipyridine substituted with at least one electron donor group, and L 1, L ₂ , L ₃ and L ₄ represent ligands forming a coordination complex with said metal M. The complex compound of claim 1, wherein the electron donor group is a hydroxy group, an alkoxy group, an aryloxy group, or a primary, secondary or tertiary amine group. Complex compound according to claim 1 or 2, wherein L represents 4,4'-dihydroxy-2,2'-bipyridine, wherein the complex has the general formula II (II) Complex compound according to claim 1 or 2, wherein L represents 4,4'-dimethoxy-2,2'-bipyridine, which complex has the general formula III Complex compound according to claims 1 or 2, wherein L represents 4,4'-bis (N, N-ethylamino) -2,2'-bipyridine, which complex has the general formula IV (IV) of ^C 2H _{5 of 2} h ₅ c ₂ h ₅ ^C 2 ^H 5 Complex compound according to any one of claims 1 to 5, wherein L 1 and L ₂ together form a divalent ligand which is ethylenediamine, 1,2-bis (2-pyridyl) ethane, oxalic acid, acetylacetone, glycine or bipyridine or phenanthroline disubstituted by R ₂ and R ₂ groups are the same or different and each group represents a hydrogen atom, N0 _2, Cl, alkyl, aryl, hydroxy, alkoxy, aryloxy or primary, secondary or tertiary amino group, wherein L ₃ and L ₄ are the same or different and each represents a monovalent ligand which is CN ", Cl ^- , Br", I ^- , SCN ", H ₂ O, NH ₃ , triphenylphosphine, trialkylphosphines, primary, secondary or tertiary amines, pyridine or pyridines substituted with Cl, NH ₂ , NO ₂ or alkyl. The complex compound of claim 6, wherein L 1 and L ₂ form a ligand identical to that of L and L ₁ and L ₄ are Cl 1. A complex compound according to any one of the preceding claims 1 to 5, wherein L 1 and L ₂ on the one hand and L ₃ and L ₄ on the other hand form a divalent ligand, the two ligands being the same or different and representing ethylenediamine; , 2-bis (2-pyridyl) ethane, oxalic, acetylacetone, glycine or a bipyridine or phenanthroline disubstituted by an R and R ₂ groups, which groups R ^ and _R2 are the same or different and each represents a hydrogen hydrogen, NO ₂ , an alkyl group, an aryl group, a hydroxyl group, an alkoxy group, an aryloxy group, or a primary, secondary or tertiary amine group. The complex compound of claim 8, which is a tris (4,4'-dihydroxy-2,2'-bipyridine) metal complex M, a tris (4,4'-dimethoxy-2,2'-bipyridine) metal complex M, and the tris (4,4'-bis (N, N, -ethylamino) -2,2'-bipyridine) metal complex M, wherein the metal M is iron, ruthenium, osmium or vanadium. A complex compound according to claims 3 and 8, wherein a L ₂ together form 4,4'-dihydroxy-2,2'-bipyridine and wherein L ₃ and L ₄ together form a bivalent ligand which is ethylenediamine, 1,2 -bis (2-pyridyl) ethane, oxalic acid, acetylacetone, glycine or bipyridine or phenanthroline which are disubstituted by R 1 and R ₂ , wherein the groups R 1 and R ₂ are the same or different and each represent an atom hydrogen, NO ₂ , Cl, alkyl, aryl, hydroxyl, alkoxy, aryloxy or a primary, secondary or tertiary amine group. A complex compound according to claim 10 which is the bis (4,4'-dihydroxy-2,2'-bipyridine) mono (2,2'-bipyridine) metal complex M, bis (4,4'-dihydroxy-2). M, bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'-dimethyl), 2'-bipyridine) mono (4,4'-dimethoxy-2,2'-bipyridine) metal complex 2,2'-bipyridine metal complex M, bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4-alkyl-2,2'-bipyridine) metal complex M, bis (4,4'-bipyridine) M, bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,7-dihydroxy-2,2'-bipyridine) mono (4-dialkyl-2,2'-bipyridine) metal complex dihydroxy (10-phenanthroline). the metal complex M, and the bis (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'-bis (N, N-ethylamino-2,2'-bipyridine) metal complex M. A complex compound according to claims 4 and 8, wherein L ₂ together form 4,4'-dimethoxy-2,2'-bipyridine and L ₃ and L ₄ together form a bivalent ligand which is ethylenediamine, 1,2-bis (2-pyridyl) ethane, oxalic acid, acetylacetone, glycine or bipyridine or phenanthroline, which are disubstituted by R 1 - and R ₂ , wherein the groups R 1 - and R ₂ are the same or different and each represents a hydrogen atom, NO ₂ , Cl, an alkyl group, an aryl group, a hydroxyl group, an alkoxy group, an aryloxy group, or a primary, secondary or tertiary amine group. A complex compound according to claim 12 which is the bis (4,4'-dimethoxy-2,2'-bipyridine) mono (2,2'-bipyridine) metal M, bis (4,4'-dimethoxy-2) metal complex. M, bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4-alkyl1-2,2), 2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) metal complex M, bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'-dialkyl-2,2'-bipyridine) metal complex M, bis (4,4'-bipyridine) -dimethoxy-2,2'-bipyridine) mono (4,7-dihydroxy-10,10-phenanthroline) metal complex M, bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'- 1,2'-bipyridine dihydroxy metal complex, and bis (4,4'-dimethoxy-2,2'-bipyridine) mono (4,4'-bis (N, Nethylamino) -2,2'-bipyridine) metal complex M. The complex compound of claims 5 and 8, wherein Lj. and L ₂ together form 4,4'-bis (N, N-ethylamino) -2,2'bipyridine and L ₃ and L ₄ together form a divalent ligand which is ethylenediamine, 1,2-bis (2-pyridyl) ethane oxalic acid, acetylacetone, glycine or bipyridine or phenanthroline which are disubstituted with Ra by R ₂ , wherein the groups R ₁ and R ₂ are the same or different and each represents a hydrogen atom, NO ₂ , Cl, alkyl, aryl a hydroxyl group, an alkoxy group, an aryloxy group, or a primary, secondary or tertiary amine group. A complex compound according to claim 14 which is the bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono- (2,2'-bipyridine) metal complex M, bis (4 4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono- (4,4'-dimethoxy-2,2'-bipyridine) metal complex M, bis (4,4'-bis ( N, N-ethylamino) -2,2'-bipyridine) mono- (4,4'-dimethyl-2,2'-bipyridine) metal complex M, bis (4,4'-bis (N, N-ethylamino) (-2,2'-bipyridine) mono (4-alkyl-2,2'-bipyridine) metal complex M, bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) M, bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono- (4,4'-alkyl-2,2'-bipyridine) metal complex the metal dihydroxy-2,2'-bipyridine complex and bis (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) mono- (4,7-dihydroxy-1,10- phenanthroline metal complex M. A complex compound according to claims 3 and 8, wherein L _x and L ₂ on the one hand and L ₃ and L ₄ on the other hand form a divalent ligand, the two ligands being the same and representing ethylenediamine, 1,2-bis (2 pyridyl) ethane, oxalic acid, acetylacetone, glycine or a bipyridine or phenanthroline disubstituted by an R ₂ group and which groups R and R ₂ are the same or different and each is hydrogen, N0 _2, Cl, an alkyl group, an aryl group, a hydroxyl group, an alkoxy group, an aryloxy group, or a primary, secondary or tertiary amine group. The complex compound according to claim 16, which is the mono (4,4'-dihydroxy-2,2'-bipyridine) bis (4,4'-dimethyl-12,2'-bipyridine) metal M complex, mono (4,4'-bipyridine). M-mono (4,4'-dihydroxy-2,2'-bipyridine) bis (4-alkyl-2,2'-dihydroxy-2,2'-bipyridine) bis (2,2'-bipyridine) metal complex M metal bipyridine complex, mono (4,4'-dihydroxy-2,2'-bipyridine) bis (4,7-dihydroxyl, 10-phenanthroline) metal M complex. A complex compound according to claims 4 and 8, wherein L 1 and L ₂ on the one hand and L ₃ and L ₄ on the other hand form a bivalent ligand, the two ligands being the same and representing ethylenediamine, 1,2-bis ( 2-pyridyl) ethane, oxalic acid, acetylacetone, glycine or bipyridine or phenanthroline, which are disubstituted by R1. and R ₂ , wherein the groups R 1 and R ₂ are the same or different and each represents a hydrogen atom, NO ₂ , Cl, an alkyl group, an aryl group, a hydroxyl group, an alkoxy group, an aryloxy group or a primary, secondary or tertiary amine group. A complex compound according to claim 18 which is a mono (4,4'-dimethoxy-2,2'-bipyridine) bis (4,4'-dimethyl-2,2'-bipyridine) metal M complex, mono (4,4'-bipyridine). M-mono (4,4'-dimethoxy-2,2'-bipyridine) bis (4-alkyl-2,2'-dimethoxy-2,2'-bipyridine) bis (2,2'-bipyridine) metal complex M metal bipyridine complex, mono (4,4'-dimethoxy-2,2'-bipyridine) bis (4,7-dihydroxy1,10-phenanthroline) metal M complex, or mono (4,4'-dimethoxy) -2,2'-bipyridine) mono (4,4'-dihydroxy-2,2'-bipyridine) mono (4,4'-dimethyl-2,2'-bipyridine) metal M complex A complex compound according to claims 5 and 8, wherein L 1 and L ₂ on the one hand and L ₃ and L ₄ on the other hand form a divalent ligand, the two ligands being the same and representing ethylenediamine, 1,2-bis (2-pyridyl) ethane, oxalic acid, acetylacetone, glycine or bipyridine or phenanthroline, which are disubstituted by R ₁ and R ₂ , wherein the groups R 1 and R ₂ are the same or different and each represents a hydrogen atom, NO ₂ , Cl, alkyl, aryl, hydroxyl, alkoxy, aryloxy or a primary, secondary or tertiary amine group. The complex compound of claim 20 which is mono (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) bis- (4,4'-dimethyl-2,2'-bipyridine) metal complex M, mono (4,4'-bis (N, N-ethylamino) -2,2'-bipyridine) bis- (2,2'-bipyridine) metal complex M, mono (4,4'-bis ( N, N-ethylamino) -2,2'-bipyridine) bis- (4-alkyl-2,2'-bipyridine) metal complex M, and mono (4,4'-bis (N, N-ethylamino) -2, 2'-bipyridine) bis- (4,746 dihydroxy-1,10-phenanthroline) metal complex M. The complex compound of any one of claims 1 to 21, wherein the metal M is osmium. The complex compound of any one of claims 1 to 21, wherein the metal M is ruthenium. The complex compound of any one of claims 1 to 21, wherein the metal M is iron. A process for the preparation of a complex compound according to any one of claims 1 to 24, characterized in that the soluble metal salt M is reacted with heating in an organic solvent gradually with a stoichiometric amount of suitable ligands, L ₂ , L ₃ and L ₄ or combinations of these ligands in the form of divalent ligands. Mediator for an amperometric sensor which is a complex compound according to any one of the preceding claims 1