Nitrile exchange reactions of [MI2(CO)3(NCMe)2] (M = Mo or W). X-ray crystal structures of the mixed-ligand seven-coordinate complexes [WI2(CO)3(NCR)(AsPh3)] (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, t Bu, CH 2 Ph or Ph; for M = Mo, R = Ph) in CH 2 Cl 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 2 Cl 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 13 C 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.