Journal of Porphyrins and Phthalocyanines, Aug 1, 2016
The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic m... more The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic macrocyclic core without any protons, A [Formula: see text] 4-(OC[Formula: see text]H[Formula: see text]C6F4 and B [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 4 or [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 5, were prepared in a straightforward manner from 3,4,5-trialkoxybenzaldehydes and a suitable dipyrrane possessing four fluorine atoms. This synthetic result paved the way to stable and at the same time liquid or low melting meso-substituted corroles. The presence of altogether eight fluorine atoms in the trans-A2B-corroles was essential to maintain corrole stability. An electrochemical study of 4 in CH2Cl showed that the behavior of this corrole is dominated by three different species in an acid base equilibrium with each other: [(A2Bcor)H2][Formula: see text], 4[Formula: see text], (A2Bcor)H3, 4 and [(A2Bcor)H4][Formula: see text], 4[Formula: see text]. Four different redox states for each of these three components could be identified in 12 separate one-electron transfer redox processes. A mechanism explaining the observed twelve redox and four chemical steps is proposed. Differential scanning calorimetry measurements have proven that if alkyl chains are long enough (C18), the corrole melts at record low temperature (63.7 [Formula: see text]C) and it is stable throughout multiple temperature variation cycles up to 300 [Formula: see text]C. Upon crystallization an initial kinetic driven crystal packing for the product is obtained that melts at 20 [Formula: see text]C, but after sufficient time has elapsed (20 h), it converts into the thermodynamically stable crystal packing form with melting point of 63.7 [Formula: see text]C, probably because of rearrangements in the alignment of the five OCH[Formula: see text]H[Formula: see text] chains in 5.
Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to co... more Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to controls, backfat from CLA fed pigs was firmer and extracted lipid contained increasing amounts of CLA, but a ±11% overall decrease in unsaturated fatty acids and a ±5% overall increase in each of C16:0 and C18:0 saturated fatty acids were noted. This resulted in a change in the melting properties of fat. The onset setting temperature increased from ±14°C to ±18°C for lipid of backfat of pigs from the 0.25 and 0.5% CLA supplementation groups, and to ±26°C for lipid from the 1% CLA supplementation group. The final melting temperatures increased from ±37°C to ±43°C and ±45°C, respectively. The presence of β'-crystals of C18:0-C16:0-C18:1c9 triacylglycerides in fat from CLA fed pigs and β-crystals in fat from 1% CLA fed pigs was observed. Fatty acid and melting point results explained the improvement in the technological quality of backfat as a result of dietary CLA supplementation.
Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, <b>1a</b>) ... more Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, <b>1a</b>) tetrabenzomonoazaporphyrin (2H-TBMAP, <b>2a</b>), tetrabenzo-<i>cis-</i>diazaporphyrin (2H-TBDAP, <b>3a</b>), tetrabenzotriazaporphyrin (2H-TBTAP, <b>4a</b>), and phthalocyanine (2H-Pc, <b>5a</b>), as well as their copper complexes (<b>1b</b>–<b>5b</b>), were synthesized. As the number of meso nitrogen atoms increases from zero to four, λ<sub>max</sub> of the Q-band absorption peak becomes red-shifted by almost 100 nm, and extinction coefficients increased at least threefold. Simultaneously the blue-shifted Soret (UV) band substantially decreased in intensity. These changes were related to the relative electron-density of each macrocycle expressed as the group electronegativity sum of all meso N and CH atom groups, ∑χ<sub>R</sub>. X-ray photoelectron spectroscopy differentiated bet...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Mammals of different species provide milk lipids with a wide variety of fatty acid composition ye... more Mammals of different species provide milk lipids with a wide variety of fatty acid composition yet with common stereospecific features. This allows the investigation of crystallographic properties of milk lipids that cannot be achieved by interesterified lipids due to the random stereospecific distribution that is obtained. The milk fats of elephant and white rhinoceros contain high amounts of 8:0, 10:0 and 12:0 which form triglyceride species that melt between 8 and 22 °C. The crystallographic behaviour of the milk lipids from blesbok and blue wildebeest differ from the other ruminant lipids, and that of horse and vervet monkey differ from the other non-ruminant lipids. It seems that a low content of 18:0 and 18:1, and a high content of saturated short- to medium-length fatty acids prevent the formation of the high and low temperature melting isotherms, between 35 and 42 °C, and between –45 and –10 °C, respectively, which are normally observed for milk fats. Keywords: Triglyceride...
Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, 1a) tetrabenzomonoazapo... more Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, 1a) tetrabenzomonoazaporphyrin (2H-TBMAP, 2a), tetrabenzo-cis-diazaporphyrin (2H-TBDAP, 3a), tetrabenzotriazaporphyrin (2H-TBTAP, 4a), and phthalocyanine (2H-Pc, 5a), as well as their copper complexes (1b-5b), were synthesized. As the number of meso nitrogen atoms increases from zero to four, λmax of the Q-band absorption peak becomes red-shifted by almost 100 nm, and extinction coefficients increased at least threefold. Simultaneously the blue-shifted Soret (UV) band substantially decreased in intensity. These changes were related to the relative electron-density of each macrocycle expressed as the group electronegativity sum of all meso N and CH atom groups, ∑χR. X-ray photoelectron spectroscopy differentiated between the three different types of macrocyclic nitrogen atoms (the Ninner, (NH)inner, and Nmeso) in the metal-free complexes. Binding energies of the Nmeso and Ninner,Cu atoms in copper chelates coul...
Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to co... more Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to controls, backfat from CLA fed pigs was firmer and extracted lipid contained increasing amounts of CLA, but a ±11% overall decrease in unsaturated fatty acids and a ±5% overall increase in each of C16:0 and C18:0 saturated fatty acids were noted. This resulted in a change in the melting properties of fat. The onset setting temperature increased from ±14°C to ±18°C for lipid of backfat of pigs from the 0.25 and 0.5% CLA supplementation groups, and to ±26°C for lipid from the 1% CLA supplementation group. The final melting temperatures increased from ±37°C to ±43°C and ±45°C, respectively. The presence of β&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-crystals of C18:0-C16:0-C18:1c9 triacylglycerides in fat from CLA fed pigs and β-crystals in fat from 1% CLA fed pigs was observed. Fatty acid and melting point results explained the improvement in the technological quality of backfat as a result of dietary CLA supplementation.
The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic m... more The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic macrocyclic core without any protons, A [Formula: see text] 4-(OC[Formula: see text]H[Formula: see text]C6F4 and B [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 4 or [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 5, were prepared in a straightforward manner from 3,4,5-trialkoxybenzaldehydes and a suitable dipyrrane possessing four fluorine atoms. This synthetic result paved the way to stable and at the same time liquid or low melting meso-substituted corroles. The presence of altogether eight fluorine atoms in the trans-A2B-corroles was essential to maintain corrole stability. An electrochemical study of 4 in CH2Cl showed that the behavior of this corrole is dominated by three different species in an acid base equilibrium with each other: [(A2Bcor)H2][Formula: see text], 4[Formula: see text], (A2Bcor)H3, 4 and [(A2Bcor)H4][Formu...
ABSTRACT The oxidation of hydrazine by tris(1,10-phenanthroline)iron(III) in acidic medium shows ... more ABSTRACT The oxidation of hydrazine by tris(1,10-phenanthroline)iron(III) in acidic medium shows first order kinetics in the oxidant, Fe-III(phen)(3)(3+). With respect to N2H4 saturation kinetics, consistent with reactant association (small k-values) prior to the redox step, has been observed. Irreversible decomposition of Fe-II(phen)(3)(2+) and Fe-III(phen)(3)(3+) cause unwanted interference in the latter stages of the reaction. An increase of [H+] has a decreasing effect on the rate of the N2H4 oxidation by Fe-III(phen)(3)(3+) and a value of K-a1 = 0.42 +/- 0.05 M (pK(a1) = 0.38) at mu = 1.0 M with N2H5+ the more reactive species has been obtained. Activation parameters, applicable to the specific experimental conditions, for the oxidation of hydrazine by re (phen)(3)(3+) have been determined as Delta H-double dagger = 69 +/- 6 kJ mol(-1) and Delta S-double dagger = -53 +/- 20 J K-1 mol(-1). A study of the decomposition of Fell(phen)(3)(2+) and Fe-III(phen)(3)(3+) have also been performed to quantify the effect of these decomposition reactions on the oxidation rate of the hydrazine. The rate of decomposition of the Fe-II(phen)(3)(2+) and Fe-III(phen)(3)(3+) are ca 50 and 75 fold slower than the N2H4 induced reduction of the tris(1,10-phenanthroline)iron(III).
ABSTRACT The reaction of [Cu(OAc)2.H2O]2 (1) with β-diketones FcCOCH2COR (R = CF3, 2a, CH3, 2b, P... more ABSTRACT The reaction of [Cu(OAc)2.H2O]2 (1) with β-diketones FcCOCH2COR (R = CF3, 2a, CH3, 2b, Ph = C6H5, 2c, and Fc = Fe(η5–C5H4)(η5–C5H5), 2d), afforded in a straightforward synthetic methodology a series of ferrocenyl-functionalized β-diketonato copper(II) complexes 3a–3d of general formula [Cu(FcCOCHCOR)2]. The environment around copper(II) is square planar with the ferrocenyl moieties being positioned opposite to each other. All complexes display in their cyclic voltammograms resolved and electrochemical reversible ferrocenyl oxidations in the range 98 ⩽ Eo′ ⩽ 420 mV versus FcH/FcH+. An electrochemical and chemical irreversible Cu(II) reduction was observed in the range −1624 ⩽ Epc ⩽ −1102 mV. Good intramolecular communication between neutral ferrocenyl and oxidised, positively charged ferrocenium cations explained the well resolved ferrocenyl redox processes. The observed intramolecular communication was quantified with the linear equation Eo′ = 98.5ΣχR − 629 which relates formal ferrocenyl oxidation potentials with the sum of R-group electronegativities, ΣχR. It was possible to show that in [Cu(FcCOCHCOFc)2], 3d, one ferrocenyl group on each β-diketonato ligand is first oxidized before the second ferrocenyl group on the same β-diketonato ligand is oxidized. In a spectro-electrochemical study, an intervalent charge transfer band (IVCT) could be detected for the mixed valent intermediates of 3d that are electrochemically generated. For complex 3a, only the normal ligand to metal charge transfer band at ca. 650 nm was observed. This demonstrate that communication between Fc and Fc+ groups are more effective within a specific β-diketonato ligand, such as (Fc+COCHCOFc) in 3d, than across a copper centre, [Fc+COCHCOR)Cu(FcCOCHCOR)], presumably because of the longer distance between the Fc⋯Fc+ species across the copper centre than within a single ligand.
Journal of Porphyrins and Phthalocyanines, Aug 1, 2016
The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic m... more The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic macrocyclic core without any protons, A [Formula: see text] 4-(OC[Formula: see text]H[Formula: see text]C6F4 and B [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 4 or [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 5, were prepared in a straightforward manner from 3,4,5-trialkoxybenzaldehydes and a suitable dipyrrane possessing four fluorine atoms. This synthetic result paved the way to stable and at the same time liquid or low melting meso-substituted corroles. The presence of altogether eight fluorine atoms in the trans-A2B-corroles was essential to maintain corrole stability. An electrochemical study of 4 in CH2Cl showed that the behavior of this corrole is dominated by three different species in an acid base equilibrium with each other: [(A2Bcor)H2][Formula: see text], 4[Formula: see text], (A2Bcor)H3, 4 and [(A2Bcor)H4][Formula: see text], 4[Formula: see text]. Four different redox states for each of these three components could be identified in 12 separate one-electron transfer redox processes. A mechanism explaining the observed twelve redox and four chemical steps is proposed. Differential scanning calorimetry measurements have proven that if alkyl chains are long enough (C18), the corrole melts at record low temperature (63.7 [Formula: see text]C) and it is stable throughout multiple temperature variation cycles up to 300 [Formula: see text]C. Upon crystallization an initial kinetic driven crystal packing for the product is obtained that melts at 20 [Formula: see text]C, but after sufficient time has elapsed (20 h), it converts into the thermodynamically stable crystal packing form with melting point of 63.7 [Formula: see text]C, probably because of rearrangements in the alignment of the five OCH[Formula: see text]H[Formula: see text] chains in 5.
Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to co... more Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to controls, backfat from CLA fed pigs was firmer and extracted lipid contained increasing amounts of CLA, but a ±11% overall decrease in unsaturated fatty acids and a ±5% overall increase in each of C16:0 and C18:0 saturated fatty acids were noted. This resulted in a change in the melting properties of fat. The onset setting temperature increased from ±14°C to ±18°C for lipid of backfat of pigs from the 0.25 and 0.5% CLA supplementation groups, and to ±26°C for lipid from the 1% CLA supplementation group. The final melting temperatures increased from ±37°C to ±43°C and ±45°C, respectively. The presence of β&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-crystals of C18:0-C16:0-C18:1c9 triacylglycerides in fat from CLA fed pigs and β-crystals in fat from 1% CLA fed pigs was observed. Fatty acid and melting point results explained the improvement in the technological quality of backfat as a result of dietary CLA supplementation.
Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, <b>1a</b>) ... more Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, <b>1a</b>) tetrabenzomonoazaporphyrin (2H-TBMAP, <b>2a</b>), tetrabenzo-<i>cis-</i>diazaporphyrin (2H-TBDAP, <b>3a</b>), tetrabenzotriazaporphyrin (2H-TBTAP, <b>4a</b>), and phthalocyanine (2H-Pc, <b>5a</b>), as well as their copper complexes (<b>1b</b>–<b>5b</b>), were synthesized. As the number of meso nitrogen atoms increases from zero to four, λ<sub>max</sub> of the Q-band absorption peak becomes red-shifted by almost 100 nm, and extinction coefficients increased at least threefold. Simultaneously the blue-shifted Soret (UV) band substantially decreased in intensity. These changes were related to the relative electron-density of each macrocycle expressed as the group electronegativity sum of all meso N and CH atom groups, ∑χ<sub>R</sub>. X-ray photoelectron spectroscopy differentiated bet...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Mammals of different species provide milk lipids with a wide variety of fatty acid composition ye... more Mammals of different species provide milk lipids with a wide variety of fatty acid composition yet with common stereospecific features. This allows the investigation of crystallographic properties of milk lipids that cannot be achieved by interesterified lipids due to the random stereospecific distribution that is obtained. The milk fats of elephant and white rhinoceros contain high amounts of 8:0, 10:0 and 12:0 which form triglyceride species that melt between 8 and 22 °C. The crystallographic behaviour of the milk lipids from blesbok and blue wildebeest differ from the other ruminant lipids, and that of horse and vervet monkey differ from the other non-ruminant lipids. It seems that a low content of 18:0 and 18:1, and a high content of saturated short- to medium-length fatty acids prevent the formation of the high and low temperature melting isotherms, between 35 and 42 °C, and between –45 and –10 °C, respectively, which are normally observed for milk fats. Keywords: Triglyceride...
Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, 1a) tetrabenzomonoazapo... more Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, 1a) tetrabenzomonoazaporphyrin (2H-TBMAP, 2a), tetrabenzo-cis-diazaporphyrin (2H-TBDAP, 3a), tetrabenzotriazaporphyrin (2H-TBTAP, 4a), and phthalocyanine (2H-Pc, 5a), as well as their copper complexes (1b-5b), were synthesized. As the number of meso nitrogen atoms increases from zero to four, λmax of the Q-band absorption peak becomes red-shifted by almost 100 nm, and extinction coefficients increased at least threefold. Simultaneously the blue-shifted Soret (UV) band substantially decreased in intensity. These changes were related to the relative electron-density of each macrocycle expressed as the group electronegativity sum of all meso N and CH atom groups, ∑χR. X-ray photoelectron spectroscopy differentiated between the three different types of macrocyclic nitrogen atoms (the Ninner, (NH)inner, and Nmeso) in the metal-free complexes. Binding energies of the Nmeso and Ninner,Cu atoms in copper chelates coul...
Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to co... more Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to controls, backfat from CLA fed pigs was firmer and extracted lipid contained increasing amounts of CLA, but a ±11% overall decrease in unsaturated fatty acids and a ±5% overall increase in each of C16:0 and C18:0 saturated fatty acids were noted. This resulted in a change in the melting properties of fat. The onset setting temperature increased from ±14°C to ±18°C for lipid of backfat of pigs from the 0.25 and 0.5% CLA supplementation groups, and to ±26°C for lipid from the 1% CLA supplementation group. The final melting temperatures increased from ±37°C to ±43°C and ±45°C, respectively. The presence of β&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-crystals of C18:0-C16:0-C18:1c9 triacylglycerides in fat from CLA fed pigs and β-crystals in fat from 1% CLA fed pigs was observed. Fatty acid and melting point results explained the improvement in the technological quality of backfat as a result of dietary CLA supplementation.
The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic m... more The liquid or low-melting free base corroles (A2Bcor)H3 with cor [Formula: see text] trianionic macrocyclic core without any protons, A [Formula: see text] 4-(OC[Formula: see text]H[Formula: see text]C6F4 and B [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 4 or [Formula: see text] 3,4,5-(OC[Formula: see text]H[Formula: see text]C6H2 for 5, were prepared in a straightforward manner from 3,4,5-trialkoxybenzaldehydes and a suitable dipyrrane possessing four fluorine atoms. This synthetic result paved the way to stable and at the same time liquid or low melting meso-substituted corroles. The presence of altogether eight fluorine atoms in the trans-A2B-corroles was essential to maintain corrole stability. An electrochemical study of 4 in CH2Cl showed that the behavior of this corrole is dominated by three different species in an acid base equilibrium with each other: [(A2Bcor)H2][Formula: see text], 4[Formula: see text], (A2Bcor)H3, 4 and [(A2Bcor)H4][Formu...
ABSTRACT The oxidation of hydrazine by tris(1,10-phenanthroline)iron(III) in acidic medium shows ... more ABSTRACT The oxidation of hydrazine by tris(1,10-phenanthroline)iron(III) in acidic medium shows first order kinetics in the oxidant, Fe-III(phen)(3)(3+). With respect to N2H4 saturation kinetics, consistent with reactant association (small k-values) prior to the redox step, has been observed. Irreversible decomposition of Fe-II(phen)(3)(2+) and Fe-III(phen)(3)(3+) cause unwanted interference in the latter stages of the reaction. An increase of [H+] has a decreasing effect on the rate of the N2H4 oxidation by Fe-III(phen)(3)(3+) and a value of K-a1 = 0.42 +/- 0.05 M (pK(a1) = 0.38) at mu = 1.0 M with N2H5+ the more reactive species has been obtained. Activation parameters, applicable to the specific experimental conditions, for the oxidation of hydrazine by re (phen)(3)(3+) have been determined as Delta H-double dagger = 69 +/- 6 kJ mol(-1) and Delta S-double dagger = -53 +/- 20 J K-1 mol(-1). A study of the decomposition of Fell(phen)(3)(2+) and Fe-III(phen)(3)(3+) have also been performed to quantify the effect of these decomposition reactions on the oxidation rate of the hydrazine. The rate of decomposition of the Fe-II(phen)(3)(2+) and Fe-III(phen)(3)(3+) are ca 50 and 75 fold slower than the N2H4 induced reduction of the tris(1,10-phenanthroline)iron(III).
ABSTRACT The reaction of [Cu(OAc)2.H2O]2 (1) with β-diketones FcCOCH2COR (R = CF3, 2a, CH3, 2b, P... more ABSTRACT The reaction of [Cu(OAc)2.H2O]2 (1) with β-diketones FcCOCH2COR (R = CF3, 2a, CH3, 2b, Ph = C6H5, 2c, and Fc = Fe(η5–C5H4)(η5–C5H5), 2d), afforded in a straightforward synthetic methodology a series of ferrocenyl-functionalized β-diketonato copper(II) complexes 3a–3d of general formula [Cu(FcCOCHCOR)2]. The environment around copper(II) is square planar with the ferrocenyl moieties being positioned opposite to each other. All complexes display in their cyclic voltammograms resolved and electrochemical reversible ferrocenyl oxidations in the range 98 ⩽ Eo′ ⩽ 420 mV versus FcH/FcH+. An electrochemical and chemical irreversible Cu(II) reduction was observed in the range −1624 ⩽ Epc ⩽ −1102 mV. Good intramolecular communication between neutral ferrocenyl and oxidised, positively charged ferrocenium cations explained the well resolved ferrocenyl redox processes. The observed intramolecular communication was quantified with the linear equation Eo′ = 98.5ΣχR − 629 which relates formal ferrocenyl oxidation potentials with the sum of R-group electronegativities, ΣχR. It was possible to show that in [Cu(FcCOCHCOFc)2], 3d, one ferrocenyl group on each β-diketonato ligand is first oxidized before the second ferrocenyl group on the same β-diketonato ligand is oxidized. In a spectro-electrochemical study, an intervalent charge transfer band (IVCT) could be detected for the mixed valent intermediates of 3d that are electrochemically generated. For complex 3a, only the normal ligand to metal charge transfer band at ca. 650 nm was observed. This demonstrate that communication between Fc and Fc+ groups are more effective within a specific β-diketonato ligand, such as (Fc+COCHCOFc) in 3d, than across a copper centre, [Fc+COCHCOR)Cu(FcCOCHCOR)], presumably because of the longer distance between the Fc⋯Fc+ species across the copper centre than within a single ligand.
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