Nitrile exchange reactions of [MI 2(CO) 3(NCMe) 2] (M = Mo or W). X-ray crystal structures of the mixed-ligand seven-coordinate complexes [WI 2(CO) 3(NCR)(AsPh 3)] (R = Et or Ph)

Abstract

Reaction of [Ml 2(CO) 3(NCMe) 2] (M = Mo or W) with an excess of NCR (for M = W, R = Et, tBu, CH 2Ph or Ph; for M = Mo, R = Ph) in CH 2Cl 2 at room temperature gives the nitrile-exchanged products [MI 2(CO) 3(NCR) 2] ( 1– 5). Equimolar quantities of 1– 5 and L (L = PPh 3, AsPh 3 or SbPh 3) react in CH 2Cl 2 at room temperature to afford the mixed ligand complexes [MI 2(CO) 3(NCR)L] ( 6– 20). X-ray single crystallographic studies were carried out on both the tungsten complexes [WI 2(CO) 3(NCR)(AsPh 3)] (R = Et and Ph). The metal atoms in both complexes have the same seven-coordinate, slightly distorted monocapped trigonal prismatic, coordination geometry, with very similar ligand dispositions. Low temperature 13C NMR spectroscopy was used to correlate the solution and solid-state structures of several of these seven-coordinate complexes. The reactions of the bis(propionitrile) complex [WI 2(CO) 3(NCEt) 2] with neutral monodentate donor ligands are also described.