Crystal and molecular structure of diphenylphosphinetetracarbonyliron

Diphenylphosphinetetracarbonyliron, Fe(CO)4PHPh2, crystallizes in the monoclinic space group P21/c with Z= 4 in a unit cell of dimensions a= 11·424, b= 12·459, c= 11·644 A, and β= 105·37°. The crystal structure analysis, using data collected with a Picker automatic diffractometer, shows the co-ordination arrangement about the iron atom to be that of a slightly distorted trigonal bipyramid (equatorial angles 119°, 117°, and 124°) with the phosphine ligand in an axial position. The Fe–P distance is 2·24 A; the mean Fe–C bond-length is 1·79 A; the mean C–O bond-length is 1·15 A. There is no difference between the observed bond-lengths in the axial and equatorial carbonyl groups. The observed P–H distance is 1·3 A. The regular geometry of this complex is contrasted with that of other Fe(CO)4L compounds.