The Crystal Structure and Low Temperature 13C NMR Spectrum of the Seven-Coordinate Complex of Tungsten(II), [WI2(CO)3(NCPh)2]

Abstract

Abstract The crystal structure of [WI2(CO)3(NCPh)2] (1) has been determined by X-ray methods. The crystals are orthorhombic, space group Pnam, a = 7.815(3), b = 13.839(5), c = 18.475(3) Å, Z = 8, R = 0.0346 for 1497 observed data. The complex [WI2(CO)3(NCPh)2] has a seven-coordinate geometry, which may be described as a distorted capped octahedron, with the two iodo-ligands mutually trans, while each nitrile is trans to a carbonyl group. The capped octahedral geometry consists of a capping carbonyl (C(10)} on the face defined by I(1), C(20) and C(20)#. However, the geom etry may also be described as a capped trigonal prism, which has one triangular face occupied by three carbonyl groups and the second triangular face occupied by N(1) , N (1)# and I(1) atoms, respectively. The iodide I(2) occupies the capping position on the rectangular face defined by the atoms C(20), C(20)#, N (1), and N (1)# . The low temperature 13C NMR spectrum (203 K, CD2Cl2) of 1 shows a single carbonyl resonance at 219.27 ppm which indicates that the complex is undergoing a rapid fluxional process in solution at 203 K.