The complex [CpFe(dppf)(CO)][B(Ar F ) 4 ] [1][B-(Ar F ) 4 ] (Cp = cyclopentadienyl, dppf = 1,1′-bis-(diphenylphosphino)ferrocene, and [B(Ar F ) 4 ] − = tetrakis[3,5bis(trifluoromethyl)phenyl]borate) was made by removal of one carbonyl ligand from the dicarbonyl complex [CpFe(CO) 2 (κ 1dppf)]I and exchange of the I − for [B(Ar F ) 4 ] − that allowed for electrochemical investigations. The cyclic voltammogram of [1] + showed a reversible anodic process due to oxidation of the ferrocenediyl moiety of the dppf ligand. A quasi-reversible cathodic process was also observed, and this reduction occurred at the CpFe moiety, as determined by variable-temperature (+22 and −30 °C) IR spectroelectrochemistry (SEC) and further supported by DFT calculations. This reduction event resulted in the formation of the two possible dimers [Cp 2 Fe 2 (μ-CO) 2 (μ-dppf)] and [Cp 2 Fe 2 (CO) 2 (μ-dppf)] along with deligation of one dppf ligand.

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...