Metal–carbonyl and metal–nitrosyl complexes. Part VIII. Molecular structure of isocyanatocyclopentadienyldinitrosylchromium

Abstract

Isocyanatocyclopentadienyldinitrosylchromium crystallises in the monoclinic system, space group P2₁/m, with Z= 2 in a cell of dimensions a= 6·18, b= 9·00, c= 7·52 Å, β= 94° 54′. Three-dimensional X-ray intensity data were collected with a counter diffractometer employing Mo-K_α radiation, and the atomic co-ordinates refined by least-squares calculations to a final R of 3·6% for 817 independent reflections. The molecule has crystallographically required C_s symmetry. The Cr–N(nitrosyl) distance, 1·716 ± 0·003 Å, and the Cr–N–O valency angle, 171·0 ± 0·2°, are in excellent agreement with the corresponding values in (π-C₅H₅)Cr(NO)₂Cl. The Cr–N-(nitrosyl) bond is very significantly shorter than the Cr–N(isocyanate) bond, 1·982 ± 0·004 Å, and must have appreciable double-bond character. The CrNCO grouping is closely linear, for the Cr–N–C and N–C–O angles are 180·0 ± 0·4° and 178·6 ± 0·6°, respectively. The Cr–C(cyclopentadienyl) distances range from 2·173–2·227 ± 0·004 Å, mean 2·20 Å.