Preparation of niobium and tantalum organoimido complexes from reactions of the pentahalides with amines: The crystal and molecular structure of bis(t-butylamine)bis(t-butylimido)bis(μ-ethoxy)tetrachloroditantalum |
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Authors: | Paul A Bates Alastair J Nielson Joyce M Waters |
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Institution: | Department of Chemistry, University of Auckland, Private Bag, Auckland, New Zealand |
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Abstract: | MCl5 (M = Nb, Ta) reacts with 2 equivalents of Me3SiNHCMe3 to give M(NCMe3)Cl3(NH2CMe3)] from which M(NCMe3)Cl3(PMe3)2] is obtained on addition of PMe3. One equivalent of Me3SiNHCMe3 reacts with MCl5 in the presence of 3 equivalents of PMe3 to give M(NCMe3)Cl3(PMe3)2] and PMe3HCl. MCl5 reacts with excess RNH2 (R = CMe3, CHMe2, CH2Me) to give M(NR)(NHR)Cl2(NH2R)] and 3 equivalents of RNH3Cl. One equivalent of alcohol replaces the amido ligand in M(NCMe3)(NHCMe3)Cl2(NH2CMe3)] to give M(NCMe3)(OR)Cl2(NH2CMe3)]2 (M = Nb, R = OCMe3; M = Ta, R = OEt). The structure of Ta(NCMe3)(μ-OEt)Cl2(NH2CMe3)]2 was determined by single-crystal X-ray diffraction methods. Crystals are triclinic, space group P with a = 9.900(5), b = 10. 161(17), c = 9.017(6) Å and α = 103.91(8), β = 97.77(4), γ = 64.40(7)°. The structure was solved by Patterson and Fourier methods and refined to an R value of 0.062 for 1319 observed data. The TaNimido and TaNamino bond lengths are 1.70(2) Å and 2.28(2) Å, respectively; the bridging TaO bond lengths are 2.01(2) Å and 2.32(2) Å, the longer one lying trans to the imido function. |
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Keywords: | Author to whom correspondence should be addressed |
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