95911-76-5Relevant articles and documents
Paramagnetic monocyclopentadienyl hydrocarbyl and borohydride compounds of vanadium(II) and vanadium(III): Synthesis, structure, and reactivity
Hessen, Bart,Lemmen, Timothy H.,Luttikhedde, Hendrik J. G.,Teuben, Jan H.,Petersen, Jeffrey L.,Huffman, John C.,Jagner, Susan,Caulton, Kenneth G.
, p. 2354 - 2362 (1987)
Paramagnetic high-spin d2 and d3 monocyclopentadienyl vanadium hydrocarbyl complexes CpVIIIR2-(PMe3)2 (R = Me, Ph) and CpVIIR(dmpe) (R = Me, Pr, Ph) have been prepared from their corresponding halide precursors. From CpV(Me)Cl(PMe3)2, prepared by ligand exchange, the mixed hydrocarbyl complex CpV(η3-C3H5)Me(PMe3) could be obtained. The V(II) borohydride complex CpV(η2-BH4)dmpe is shown by EPR and solution magnetic measurements to have a low-spin (S = 1/2) d3 configuration. X-ray structures of CpVMe(dmpe) (P212121, a = 12.526 (3) A?, b = 9.285 (2) A?, and c = 12.772 (3) A? at -158°C, Z = 4) and CpV(BH4)dmpe (P21/m, a = 8.198 (2) A?, b = 13.435 (3) A?, c = 13.987 (4) A?, and β = 102.09 (1)° at -160 °C, Z = 4) have been determined. Several structural and electronic features are correlated to EHMO calculations. Both V(II) and V(III) alkyl compounds have been reacted with molecular hydrogen. Although catalytic activity in hydrogenation and isomerization of olefins has been observed, no stable V(III) hydrido species could be obtained, reductive elimination processes probably precluding their isolation. Reaction of CpVMe2(PMe3)2 with H2 generates active CpV fragments that can bind ligands like benzene and 2,3-dimethyl-1,3-butadiene.
Cyclopentadienylvanadium(III) and -vanadium(II) methyl, phenyl, and borohydride compounds
Hessen, Bart,Teuben, Jan H.,Lemmen, Timothy H.,Huffman, John C.,Caulton, Kenneth G.
, p. 946 - 948 (2008/10/08)
Reaction of CpVCl2(PMe3)2 with MeLi and PhMgBr yields CpVMe2(PMe3)2 and CpVPh2(PMe3)2, respectively. Conproportionation of CpVCl2(PMe3)2 and CpVMe2(PMe3)2 gives selective conversion to CpVMe(Cl)(PMe3)2. These paramagnetic compounds show isotropic 1H NMR shifts of the P-Me protons. CpVMe2(PMe3)2 reacts rapidly with CO to give acetone and diagCpV(CO)2(PMe3)2. Borohydride converts CpVCl(Me2PCH2CH2PMe2) to CpV(η2-BH4)(dmpe), shown to have one unpaired electron, two less than its chloride precursor. Conversion of this monochloride to CpVR(dmpe) occurs with MeLi and PhMgBr. The monomethyl compound has a low VC-H stretching frequency (2750 cm-1), but the crystal structure shows no agostic hydrogen to be involved. Crystal data (-158°C): a = 12.526 (3) A?, b = 9.285 (2) A?, c = 12.772 (3) A?, Z = 4 in space group P212121.
