7-COORDINATE COMPLEXES OF MOLYBDENUM(II) AND TUNGSTEN(II) CONTAINING IMIDAZOLE AND METHYL-SUBSTITUTED IMIDAZOLES AS ATTACHED LIGANDS

The reaction of [MI2(CO)3(NCMe)2) (M = Mo or W) with an equimolar amount of L {L = imidazole (im), 2Me-imidazole (2Me-im) (for M = W only) or 4Me-imidazole (4Me-im)} gave [M(mu-I)I(CO)3L]2 (1-5). Two equivalents of L (L = im, 2Me-im or 4Me-im) react with [MI2(CO)3(NCMe)2] to afford [MI2(CO)3L2] (6-11). A series of mixed-ligand complexes of the type [MI2(CO)3LL'] (M = Mo or W, L = im, L' = PPh3, AsPh3 or SbPh3; L = 2Me-im, L '= PPh3; for M = W, L = 4Me-im, L' = PPh3 or SbPh3) (12-21) have also been prepared. The new complexes 1-21 have all been characterised by elemental analysis (C, H and N), IR and H-1 NMR spectroscopy. Magnetic susceptibility measurements show all the complexes 1-21 to be diamagnetic.