GB1514805A - Photographic silver halide developer compositions - Google Patents

Abstract

1514805 Developers containing ruthenium complexes EASTMAN KODAK CO 26 June 1975 [26 June 1974 9 Sept 1974] 27127/75 Heading G2C A photographic silver halide developing composition contains at least one silver halide developing agent, and a ruthenium (III) or ruthenium (II) cationic complex wherein all or a majority of the co-ordinating atoms are nitrogen atoms of amine or ammine ligands, each developing agent exhibiting in the absence of other developing agents and the ruthenium complex a silver halide development induction period of at least five seconds and at least one developing agent exhibiting a rate of reduction of ruthenium (III) in said ruthenium III complex or produced by oxidation of said ruthenium (II) complex greater than its rate of reduction of silver halide in the absence of the ruthenium complex. The invention also includes a method of increasing the developing activity of a photographic developing composition whereof each silver halide developing agent is polyhydroxybenzene, ascorbic acid, hydroxylamine, hydroxyurea or pyrimidine developing agent which comprises incorporating in the composition a development accelerating amount of at least one ruthenium (II) or ruthenium (III) cationic complex wherein all or a majority of the co-ordinating atoms are nitrogen atoms of amine or ammine ligands. The ruthenium complex acts as a catalyst for silver halide by forming a redox couple between the developing agent and the silver halide. Ligands in the ruthenium complexes include acyclic aliphatic amines, e.g. comprising alkyl, alkylene and alkanonal moieties. Examples are ammonia, ethylene diamine, triethylene diamine, alkyl tetramines, pyridine, morpholine, pyrrole, pyrazole, pyrazine, pyrazoline, oxazole and thiazole. The complexes may contain 1 or 2 monodentate ligands such as water, halogen, thiocyanate, methylcarboxylato, isonicotinamido. Suitable anions are listed. Developing agents are also listed. With hydroquinone a carbonylbisulphite-amine condensation product is preferably present, amines for their preparation being given. The effect of the complexes with developing agents having the specified induction period and with others, not according to the invention, is illustrated.