Crystal structure of tetracarbonyl-[1-(dimethylarsino)-2-(diphenylphosphino)tetrafluorocyclobutene-P]-iron

Abstract

The title compound crystallizes in the monoclinic space group P2₁/c and has a unit cell of dimensions: a= 11·284(4), b= 10·800(6), c= 19·755(8)Å, β= 96·85(2)°, Z= 4. By use of three-dimensional data collected by counter methods, the structure was solved by the symbolic addition procedure and refined by full-matrix least squares to R 0·040 for 1149 observed reflections. The co-ordination geometry about the iron atom is a slightly distorted trigonal bipyramid. The ligand co-ordinates through the phosphorus atom in an axial position, Fe–P being 2·224(3)Å. There are no significant differences between axial and equatorial iron–carbon bond lengths, mean 1·74(2)Å. The arsenic atom lies above a phenyl ring with As–C contacts ranging from 3·44–4·19 Å.