Get access

Imido-Supported Borohydrides of Titanium, Vanadium and Molybdenum



New imido bis(borohydride) complexes [(RN=)M(PMe3)22-BH4)2] [R = Ar, M = Ti (3); R = Ar, M = V (5); R = Ar, M = Mo (6); R = Ar′, M = Mo (7); Ar = 2,6-iPr2C6H3, Ar′ = 2,6-Me2C6H3] were prepared by the reaction of dichlorides [(RN=)MCl2(PMe3)n] (M = Ti, n = 2; M = V, n = 2, M = Mo, n = 3) with LiBH4 (2 equiv) in THF. Compounds 3, 5, 6 and 7 were studied by IR spectroscopy and X-ray diffraction, and an EPR spectroscopy study was performed for paramagnetic compound 5. In 3, the two borohydride units are orthogonal to each other as a result of the overlap of an antiphase combination of B–H orbitals with the empty dxy orbital of Ti. In contrast, the dxy orbital of the metal atom is singly occupied in 5 and fully occupied in 6 and 7, and both borohydride ligands are oriented in the same way, with the B(μ-H2)M moieties orthogonal to the P–M–P vector.