Metal-metal communication between 1,1'-bis(diphenylphosphino)cobaltocenium and an organonickel moiety.

1,1'-Bis(diphenylphosphino)cobaltocenium (dppc) + , similar to 1,1'-bis(diphenylphosphino)ferrocene, can be coordinated by dicarbonylnickel(0) or cyclopentadienylnickel(II), respectively. The cyclic voltammogram of [Ni(CO) 2 (dppc)] + ([1] + ) showed two reversible reductions, at potentails nearly identical to (dppc) + . The ligand-based reductions were confirmed by IR spectroelectrochemistry (SEC), although the Δ ν CO was larger than might be expected if the ligand was electronically decoupled to the Ni(CO) 2 moiety. The larger Δ ν CO was attibuted to changes in the donor/accpetor properties of the -PPh 2 moeities based on the occupation of the Co-Cp anti-bonding orbital, where the Cp ligand adopts an ylide-like structure. A similar analysis was performed on [CpNi(dppc)] 2+ ([2] 2+ ), where the two reductions were anodically shifted by Δ E = 292 and 520 mV from (dppc) + , indicating an increase in the M-M communication. The EPR SEC spectrum for [2] + showed that the cobalt was reduced, while the UV-Vis-NIR SEC spectrum for [2] + showed a NIR absportion at 1200 nm assinged as a MMCT Co II → Ni II band. The second reduction formed [2] 0 which was EPR silent but the UV-Vis-NIR SEC spectrum showed an increase in the intensity of the MMCT Co I → Ni II .