Carbon compounds of the transition metals. Part XXII. Crystal and molecular structure of (tetraphenylbutatriene)tetracarbonyliron

Abstract

The crystal structure of (tetraphenylbutatriene)tetracarbonyliron has been determined from 1395 visually-estimated X-ray intensities and refined to R 7·1%. The unit-cell parameters are a= 12·64, b= 10·25, c= 20·17 Å, β= 93·25°, Z= 4 and the space group is P2₁/c. The iron atom is co-ordinated exclusively to the central bond of the cumulative double-bond system; the metal co-ordination is trigonal bipyramidal and the butatriene chain lies in the equatorial plane. The four carbon atoms of the butatriene chain are no longer colinear in the complex. The terminal carbon atoms of the chain are bent away from the iron atom so that the angles subtended at the central carbon atoms are 151°. The three C–C distances in the chain are equal with mean value 1·34 Å; other distances are Fe–CO 1·77, Fe–C(chain) 2·05, and C–O 1·16 Å.