Putting cyaphide in its place: determining the donor/acceptor properties of the κC-cyaphido ligand

Abstract

The synthesis of group 9 pyridine–diimine complexes M(^DippPDI)X and [M(^DippPDI)L]⁺ (M = Co, Rh; ^DippPDI = 1,1′-(pyridine-2,6-diyl)bis(N-(2,6-diisopropylphenyl)ethan-1-imine); X = CP⁻, CCH⁻; L = CO, ^tBuNC) bearing a series of strong-field ligands, including the cyaphide ion (CP⁻), is reported. A combined experimental and computational comparative study of the group 9 PDI cyaphide complexes Co(^DippPDI)(CP) and Rh(^DippPDI)(CP), as well as the N-heterocyclic carbene (NHC) gold(I) cyaphide complex Au(IDipp)(CP) (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), reveals the σ donor and π acceptor properties of the κC-cyaphido ligand, and allow us to suggest a position for this ion in the spectrochemical series.