DICARBONYL AND TRICARBONYL ADDUCTS OF (W-EQUIVALENT-TO-W)(6-CONTAINING COMPLEXES - PREPARATION AND STRUCTURES OF W-2(OCME(2)CF(3))(6)(CO)(2) AND W-2(OCME(CF3)(2))(4)(NME(2))(2)(CO)(3)())

Carbon monoxide adds reversibly to W-2(OR)(6) compounds to give W-2(OR )(6)(CO)(2) complexes (R = Si(t)BuMe(2), 1; CMe(2)CF(3), 2; 2,6-Me(2)C (6)H(3), 3) wherein the CO ligands bond to alternate tungsten atoms in a manner that allows mixing of WW pi and W d pi to CO pi bonding. In contrast to the homoleptic alkoxides above, the mixed amido-alkoxide complex W-2(OCMe(CF3)(2))(4)(NMe(2))(2) (4), which also takes up 2 equ iv of CO, reacts further to give W-2(OCMe(CF3)(2))(4)(NMe(2))(2)(CO)(3 ) (6), which has an unusual structure wherein three CO ligands are bon ded to a single tungsten atom and the W-W bond is supported by one NMe (2) bridge. The formation of 6 is also reversible. 2 and 6 have been c haracterized by single-crystal X-ray crystallography, and all compound s have been characterized by H-1 and C-13{H-1} NMR spectroscopy. The r esults are compared to earlier studies of the addition of CO to Mz(OR) 6 complexes such as W-2((OBU)-B-t)(6), which give bridged monocarbonyl adducts, and that of Wolczanski et al. (Miller, R. L.; Wolczanski, P. T.; Rheingold, A. L. J. Am. Chem. Sec. 1993, 115, 10422) wherein CO a nd W2Cl2(silox)(4) (silox = (t)Bu(3)SiO) react reversibly to give a bi s(carbonyl) adduct with subsequent cleavage to give (silox)(2)(O)W(mu- C)W(silox)(2)Cl-2. For 2, C26H36F18O8W2, FW = 1186.2; a = 11.256(4), b = 18.496(6), c = 17.789(7) Angstrom; beta = 97.97(1)degrees; monoclin ic P2(1)/n, Z = 4. For 6, C23H24F24N2O7W2, FW = 1264.1; a = 14.053(3), b = 21.148(5), 12.789(3) Angstrom; alpha = 106.11(1), beta = 103.15(1 ), gamma = 86.81(1)degrees; triclinic P ($) over bar 1, Z = 4.