Synthesis, structure and substitution pattern study of phosphine-substituted dimetallic Fischer carbene complexes of cymantrene

Phosphine-substituted Fischer carbene complexes of cymantrene [M′(CO)xPPh3{C(OEt)(C5H4M(CO)3)}] where M = Mn, M′ = Cr, x = 4 (1); M = Mn, M′ = Mo, x = 4 (2); M = Mn, M′ = W, x = 4 (3) and M = Mn, M′ = CpMn, x = 1 (4) have been synthesized through thermal substitution of carbonyl ligands in the presence of triphenylphosphine. Through the variation of the carbene metal group, subtle structural differences were witnessed. DFT calculations indicated that three plausible substituted structures were possible namely substitution of a carbonyl ligand on the tricarbonyl cymantrene synthon or the substitution of either a cis or trans carbonyl group on the carbene metal coordination sphere. The solid state crystal structures of three of the complexes provided insight into the bonding preference of the ligand towards the two available metal centres. Substitution of a cis carbonyl ligand was favoured in all four complexes. A DFT study provided rationalization into electronical and sterical aspects of the phosphinated dimetallic carbene complexes. Bonding and electronic insights into ligand-metal interactions in the complexes were discussed using calculated Wiberg bond indices, bond dissociation enthalpies and solid angle analysis. Theoretical aspects were confirmed with solid state structural data.

Graphical AbstractSynthesis, X-ray study and NBO analysis of phosphine-substituted dimetallic Fischer ethoxy carbene complexes of cymantrene.Figure optionsDownload as PowerPoint slide