Single and double carbon–carbon bond formation in an ethenylidene bridged di-iron complex. X-Ray crystal structure of a 3,3-dicyanoallenylidene bridged di-iron complex

Abstract

Tetracyanoethylene reacts with [Cp₂Fe₂(µ-CO)(µ-P–P)(µ-CCH₂)](Cp=η⁵-C₅H₅)[P–P = 1,2-bis(diphenylphosphino)ethane = dppe, or P–P = bis(diphenylphosphino)methane = dppm] to give the µ-3,4,4-tricyanobuta-1,3-dienylidene complexes [Cp₂Fe₂(µ-CO)(µ-P–P){µ-CCH–C(CN)=C(CN)₂}] exhibiting strong absorption in their visible spectra, and the µ-dicyanoallenylidene complex [Cp₂Fe₂(µ-CO)(µ-P–P){µ-CCC(CN)₂}] whose structure has been determined by X-ray diffraction (P–P = dppe).