Poly(azolyl) chelate chemistry. Part 10 - Hydrotris(methimazolyl)borato alkylidyne complexes of tungsten

The syntheses of the alkylidyne complexes [W(dropCR)(CO)(2){HB(mt)(3)}] (R = (NPr2)-Pr-i 1a, C4H3S-2 1b, CdropCCMe(3) 1C, C6H4Me-4 1d, C6H3Me2-2,6 1e, C5H4Mn(CO)(3) If; mt = 2-mercapto-3-methylimidazolyl) are reported. The crystal structures of three examples (1a, 1b, and 1c) reveal a progressive distortion of the alkylidyne ligand from octahedral coordination at tungsten, and in addition have a chiral C-3-symmetric conformation for the B(mt)(3)W cage, which is also implicit from solution NMR data. A set of parameters is suggested for describing the geometry of HB(mt)(3)M cages.