Carbon compounds of the transition metals. Part XXVII. Crystal and molecular structure of [bis(biphenylylidene)butatriene]hexacarbonyldi-iron, a binuclear metal cumulene complex

Abstract

The crystal structure of the title complex has been determined from 1351 visually estimated X-ray intensities and refined by least-squares methods to R 6·9%. The unit-cell parameters are a= 16·36, b= 10·83, c= 16·47 Å, β= 110·13°, Z= 4, space group P2₁/n. The butatriene chain is bent into a zig-zag in which the bond angles at the central chain atoms are 128 ° and the iron atoms may be regarded as bonded to the chain viaσ bonds to the central carbons and via π bonds to the terminal double bonds. The three C–C(chain) distances are equal. Distances are : Fe–Fe (2·596(4), mean Fe–CO 1·77(1), mean Fe–C(chain) 2·39 and 2·04 (π), 1·94 (σ), mean C–C(chain) 1·39 Å.