Triazenide-bridged dirhodium complexes containing redox-active cyanomanganese ligands

The complex [Rh2(CO)4(µ-RN3R)2]1 reacted with the cyanomanganese ligands cis-[Mn(CN)(CO)2(L–L)][L–L = Ph2PCH2PPh2(dppm), L = P(OEt)32 or P(OPh)33; L–L = Ph2PCH2CH2PPh2(dppe), L = PEt34] in n-hexane under reflux, or with trans-[Mn(CN)(CO)2L(L–L)][L–L = dppm, L = P(OEt)38 or P(OPh)39] or [Mn(CN)(NO)L(cp′)][L = P(OPh)312 or PPh313, cp′=η-C5H4Me], in CH2Cl2 in the presence of ONMe3, giving [Rh2{(µ-NC)MnLx}(CO)3(µ-RN3R)2]{Lx=cis-(CO)2[P(OEt)3](dppm)5, cis-(CO)2[P(OPh)3](dppm)6, cis-(CO)2(PEt3)(dppe)7, trans-(CO)2[P(OEt)3](dppm)10, trans-(CO)2[P(OPh)3](dppm)11, (NO)[P(OPh)3](cp′)14 or (NO)(PPh3)(cp′)15}. The tricarbonyls underwent one-electron oxidation at a platinum-disc electrode and reacted with [Fe(cp)2][PF6](cp =η-C5H5) in CH2Cl2 to give the corresponding paramagnetic complexes 5+–7+, 10+, 11+, 14+ and 15+ which contain [Rh2]3+ cores. The addition of compounds 2 or 8 to 5+ or 10+, or of 3 or 9 to 6+ or 11+, resulted in further carbonyl substitution to give the dicarbonyl complexes [Rh2{(µ-NC)MnLx}2(CO)2(µ-RN3R)2]+16+–21+ which reacted with [Fe(cp)2][PF6] in the presence of chloride ion to give the diamagnetic [Rh2]4+-containing cations [Rh2Cl{(µ-NC)MnLx}2(CO)2(µ-RN3R)2]+22+–24+. The ESR spectra of the paramagnetic [Rh2]3+-containing cations, and the effects of varying the cyanomanganese ligand on the order in which the redox-active sites (Rh2 and Mn) of the tri- and tetra-metallic complexes are oxidised, are discussed.