Centro de Espectroscopia de Resonancia Magnética Nuclear, CAI en Química, Universidad de Alcalá de Henares, Campus Universitario, E-28871, Alcalá de Henares, Spain.
Dalton Trans. 2011 Jan 14;40(2):413-20. doi: 10.1039/c0dt00878h. Epub 2010 Nov 26.
Pseudooctahedral complexes [MCl(3)(NtBu)L(2)] (M = Nb, L = py 1, ½ tmeda 3; M = Ta, L = py 2, ½ tmeda 4) have been studied by spectroscopic methods. By a VT (1)H NMR experiment a mutual exchange process between the py(ax) and py(free) in the complexes 1-2 was observed, whereas (13)C and (15)N NMR studies showed in the complexes 3-4 a tmeda ligand with an axial/equatorial coordination mode. The reaction of 2 with 3 equiv of Grignard reagent produces the methathesis products [TaR(3)(NtBu)] (R = CH(2)CMeCH(2)5, CH(2)CHCHCH(3)6) in which 2-methylallyl and 2-butenyl groups appear with a η(3)- and σ-coordination mode, respectively. When, toluene solutions of the compounds 5-6 were treated with 2 equiv of 2,6-dimethylphenylisocyanide the imido bisiminoacyl compounds [TaR(NtBu){C(R)NAr-κ(1)C}(2)] (Ar = 2,6-Me(2)C(6)H(3); R = CH(2)CMeCH(2)7, CH(2)CHCHCH(3)8) can be isolated, via an imido iminoacyl intermediate [TaR(2)(NtBu){C(R)NAr-κ(1)C}] (Ar = 2,6-Me(2)C(6)H(3); R = CH(2)CMeCH(2)9) as we have observed in the treatment of 5 with 1 equiv of isocyanide; however, the analogous reaction between 5 and COPh(2) leads to the formation of the trisalkoxo imido compound [Ta(OCPh(2)R)(3)(NtBu)] (R = CH(2)CMeCH(2)10). All new complexes were studied by IR and multinuclear NMR spectroscopy.
八面体配合物[MCl(3)(NtBu)L(2)]（M = Nb，L = py 1，½ tmeda 3；M = Ta，L = py 2，½ tmeda 4）已经通过光谱方法进行了研究。通过 VT（1）H NMR 实验，观察到配合物 1-2 中 py(ax)和 py(free)之间的相互交换过程，而（13）C 和（15）N NMR 研究表明，在配合物 3-4 中，tmeda 配体具有轴向/赤道配位模式。配合物 2 与 3 当量格氏试剂反应生成复分解产物[TaR(3)(NtBu)]（R = CH(2)CMeCH(2)5，CH(2)CHCHCH(3)6），其中 2-甲基丙烯基和 2-丁烯基分别以η(3)-和σ-配位模式出现。当将化合物 5-6 的甲苯溶液与 2 当量的 2,6-二甲基苯基异氰化物一起处理时，可以通过亚胺亚胺酰基中间体[TaR(NtBu){C(R)NAr-κ(1)C}(2)]（Ar = 2,6-Me(2)C(6)H(3)；R = CH(2)CMeCH(2)7，CH(2)CHCHCH(3)8）分离出亚胺二异氰酸酯化合物[TaR(2)(NtBu){C(R)NAr-κ(1)C}]（Ar = 2,6-Me(2)C(6)H(3)；R = CH(2)CMeCH(2)9），因为我们已经观察到 5 与 1 当量异氰化物反应时形成了该中间体；然而，5 与 COPh(2)的类似反应导致形成三烷氧基亚胺化合物[Ta(OCPh(2)R)(3)(NtBu)]（R = CH(2)CMeCH(2)10）。所有新配合物均通过 IR 和多核 NMR 光谱进行了研究。
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