Triazenide-bridged dirhodium complexes containing redox-active cyanomanganese ligands

The complex [Rh-2(CO)(4)(mu-RN(3)R)(2)] 1 reacted with the cyanomanganese ligands cis-[Mn(CN)(CO)(2)(L-L)] [L-L=Ph(2)PCH(2)PPH(2) (dppm), L=P(Oet)(3) 2 or P(OPh)(3) 3; L-L =Ph(2)PCH(2)CH(2)PPh(2) (dppe), L=PEt(3) 4] in n-hexane under reflux, or with trans-[Mn(CN)(CO)(2)L(L-L)] [L-L=dppm, L=P(OEt)(3) 8 or P(OPh)(3) 9] or [Mn(Cn)(NO)L(cp')] [L=P(OPh)(3) 12 or PPh(3) 13, cp'=eta-C(5)H(4)Me], in CH2Cl2 in the presence of ONMe(3), giving [Rh-2{(mu-NC)MNL(x)}(CO)(3)(mu-RN(3)R)(2)] {L(x)=cis-(CO)(2)[P(OEt)(3)](dppm) 5, cis-(CO)(2)-[P(OPh)(3)](dppm) 6, cis-(CO)(2)(PEt(3))(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)(PPh(3))(cp') 15}. The tricarbonyls underwent one-electron oxidation at a platinum-disc electrode and reacted with [Fe(cp)(2)][PF6](cp=eta-C5H5) in CH2Cl2 to give the corresponding paramagnetic complexes 5(+)-7(+), 10(+), 11(+), 14(+) and 15(+) which contain [Rh-2](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 [Rh-2{(mu-NC)MnL(x)}(2)(CO)(2)(mu-RN(3)R)(2)](+)16(+)-21(+) which reacted with [Fe(cp)(2)][PF6] in the presence of chloride ion to give the diamagnetic [Rh-2](4+)-containing cations [Rh2Cl{(mu-NC)MnL(x)}(2)(CO)(2)(mu-RN(3)R)(2)](+)22(+)-24(+). The ESR spectra of the paramagnetic [Rh-2](3+)-containing cations, and the effects of varying the cyanomanganese ligand on the order in which the redox-active sites (Rh-2 and Mn) of the tri- and tetra-metallic complexes are oxidised, are discussed.