SYNTHESIS AND CHARACTERIZATION BY H-1, C-13, AND F-19 NMR-SPECTROSCOPY OF (CH3CN)N(CO)4-N(NO)W(MU-F)BF3 AND [(CH3CN)N+1(CO)4-N(NO)W][BF4] (N = 0-2), TUNGSTEN MONONITROSYL CARBONYL CATIONS WITH LABILE ACETONITRILE AND [(MU-F)BF3]- LIGANDS

Addition of [NO][BF4] to CH3CNW(CO)5 in CH2C12 gives a mixture of five mononitrosyl compounds, mer-(cis-CH3CN)-(trans-NO)(CO)3W(µ-F)BF3 (1), [mer,cis-(CH3CN)2W(CO)3(NO)] [BF4] (2a), cis,cis,trans-(CH3CN)2(CO)2(NO)W(µ-F)BF3 (3), [fac-(CH3CN)3W(CO)2(NO)][BF4] (4a), and trans-(NO)(CO)4W(µ-F)BF3 (5); in a typical experiment the yield is 90%, and the ratio 1:2a:3:4a:5 is 47:14:11:1:27. Addition of acetonitrile to the mixture results in substitution of the [(µ-F)BF3]− ligand of 1, 3, and 5 with conversion to 2a, 4a, and [trans-(CH3CN)W(CO)4NO][BF4] (6), respectively; allowing the mixture to stand in the presence of excess acetonitrile results in complete conversion of 2a and 6 to 4a. Further support for the identities of 1–5 is obtained by reaction of the mixture with Me3P, giving [mer-(cis-CH3CN)(trans-Me3P)W(CO)3(NO)][BF4] (7a), [cis,cis,-trans-(CH3CN)2(CO)2(NO)W(PMe3)][BF4] (8a), [trans-Me3P(CO)4WNO] [BF4] (9), and the previously reported compound [mer,cis-(Me3P)2W(CO)3(NO)][BF4] (10a). The reaction mixtures are analyzed by IR and 1H, 13C, and 19F NMR spectroscopy. In particular, the 13C NMR spectrum exhibits quintets for the carbonyl ligands of 1, 3, and 5 due to a dynamic “spinning” process of the [(µ-F)BF3]− ligand, and the 19F NMR spectrum exhibits doublets for the terminal fluorine atoms (which are further separated into l0B and 11B isotopomers) near −153 ppm and quartets for the bridging fluorine atoms from −203 to −238 ppm. Independent synthesis and isolation in good yield of 2b−c, 4a−d, 7b−c, and 8b (where the anions for a−d are [BF4]−, [SbF6]−, [(C6H5)4B]−, and [PF6]− respectively) are described, as are the independent synthesis and spectroscopic characterization of 3, 5, and 6. © 1990, American Chemical Society. All rights reserved.