Elektrochemische synthesen: XXII. Die kathodische reduktion von pentacarbonyl-chrom-halogenphosphanen

The cathodic reduction of the trihalophosphane complexes (CO)₅CrPX₃ (1a, X = Cl; 1b, X = Br) leads to the binuclear complexes (CO)₅ Cr(X₂PPX₂)Cr(CO)₅, (2a, X = Cl; 2b, X = Br). Reductive dehalogenation of coordinated organodihalophosphanes, (CO)₅CrPRX₂ (3a, R = Me, X = Cl; 3b, R = Ph, X = Cl; 3c, R = Me, X = Br; 3d, R = Ph, X = Br), in the presence of dimethyldisulfane yields bis(methylthio)organophosphane complexes, (CO)₅CrPR(SCH₃)₂ (5a, R = Me; 5b, R = Ph). The phosphinidene complexes (CO)₅ CrPR are discussed as the reactive intermediates.The organodibromophosphane complexes 3c and 3d can also be partially reduced in the presence of dimethyldisulfane, and (CO)₅CrPBrR(SCH₃) (7a, R = Me; 7b, R = Ph) is obtained. Radical intermediates are probable.