Synthesis and structural analysis of the mixed-ligand seven-coordinate complexes [MI2(CO)2{P(OR)3} {Ph2P(CH2)nPPh2}] (M = Mo, R = Me, Et, n=1; R = Et, iPr, Ph, n=2; M = W, R = Ph, n=1; R = Me, Et, iPr, n=2).: A system where the ligand cone angle and ligand 'bite' angle do not affect the coordination geometry

Reaction of [MI2(CO)(3)(NCMe)(2)] with an equimolar amount of Ph2P(CH2)(n)PPh2 in CH2Cl2 at room temperature gave [MI2(CO)(3) {Ph2P(CH2)(n)PPh2)], which, followed by an in situ reaction with one equivalent of P(OR)(3), afforded the mixed-ligand seven-coordinate complexes [MI2(CO)(2){P(OR)(3)} (Ph2P(CH2)(n)PPh2}] (M = Mo, R = Me, Et, n = 1; R = Et, 'Pr, Ph, n = 2; M = W, R = Ph, n = 1; R = Me, Et, 'Pr, n = 2) (1-9) in good yield. All nine complexes have been crystallographically characterised, and they all have surprisingly very similar capped octahedral geometries with a carbonyl group capping an octahedral face containing a carbonyl, the phosphite ligand and one of the phosphorus atoms of the bidentate phosphine ligand. It appears that the different steric effects of the phosphite ligands and angle of bite of the bidentate phosphines do not cause any significant structural differences. (C) 1999 Elsevier Science S.A. All rights reserved.