Complexes of molydenum-(V) and -(VI) with L-cysteine and related compounds and their reactions with hydrogen sulphide

Abstract

We have prepared the following complexes: for L =α-alanine and β-alanine, Mo^VI₂O₄(OH)₃L; for L = 2-mercapto-ethylamine, [Mo^VIO₂L₂], [Mo₅O₉S₃L₆], [Mo₄O₃L₅],2H₂O, [Mo₃OS₅L₄],2H₂O; for L = L-cysteine methyl ester,[Mo^VIO₂L₂]. [Mo₂^VO₃L₄], [Mo₂^VO₂S₂L₂]; for L = 2-mercaptoethanol, [Mo₂^vO₃L₄], [Mo₂^VO₄L₂]; and for L =L-cysteine, Na₂[Mo^VIO₂L₂], dimethylformamide, Na₂[Mo^V₂O₄L₂],5H₂O, Na₂[Mo₂^VO₂S₂L₂],3H₂O. The oxocomplexes were prepared from aqueous solutions of molybdenum-(VI) and -(V) and the ligands. With hydrogen sulphide some of the complexes gave complexes in which bridging oxide ligands had been replaced by sulphide. The complexes are diamagnetic. We report their i.r. and electronic spectra and discuss their structures, the effect on their spectra and other properties of different donor atoms (N,O,S), and their relevance as models for molybdenum-containing enzymes.