Department of Inorganic Chemistry, University of Castilla-La Mancha, Ciudad Real, Spain.
Dalton Trans. 2010 Feb 28;39(8):1962-71. doi: 10.1039/b918298e. Epub 2010 Jan 11.
The reactions of phosphido complexes [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(L)(PPh(2))] [L = CO (1), CNxylyl (2), CNCy (3)] with alkynes have been carried out. The new diphenylphosphinoalkenyl niobocene complexes [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(CO(2)CH(3))=C(R)PPh(2))(CO)] [R = H (4), CH(3) (5)] and [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(CO(2)R)=C(CO(2)R)PPh(2))(CO)] [R = CH(3), (6), R = (t)Bu, (7)] were successfully synthesized by the reaction of with methyl propiolate (HC[triple bond]CCO(2)CH(3)) or methyl 2-butynoate (CH(3)C[triple bond]CCO(2)CH(3)) and dimethyl 2-butynedioate [(CH(3) O(2)C)C[triple bond]C(CO(2)CH(3))] or di(tert-butyl) 2-butynedioate [((t)BuO(2)C)C[triple bond]C(CO(2)(t)Bu)], respectively. However, reaction was not observed with more electron-rich alkynes. Complex reacted with methyl propiolate, methyl 2-butynoate (MeC[triple bond]CCO(2)Me) or di(tert-butyl) 2-butynedioate to give surprising new heteroniobacycle complexes [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(=NXylyl)C(R(1))=C(R(2))PPh(2)-kappa(1)-P)] [R(1) = H, R(2) = CO(2)Me (8); R(1) = Me, R(2) = CO(2)Me (9); R(1) = CO(2)(t)Bu, R(2) = CO(2)(t)Bu (10)]. Finally, the phosphido complexes and reacted with phenylacetylene (PhC[triple bond]CH) to give new diphenylphosphinoalkenyl niobocene derivatives [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(C(6)H(5))=C(H)PPh(2))(CNR)] [R = xylyl (11), Cy (12)]. All of these compounds were characterized by NMR spectroscopy and the molecular structure of was determined by single-crystal X-ray diffraction studies. Theoretical studies were also carried out by means of density functional theory (DFT) calculations on the insertions of alkynes into the Nb-P bond in the phosphido niobocenes.
膦配合物 [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(L)(PPh(2))] [L = CO (1), CNxylyl (2), CNCy (3)] 与炔烃的反应已经进行。新的二苯基膦烯基钽配合物 [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(CO(2)CH(3))=C(R)PPh(2))(CO)] [R = H (4), CH(3) (5)] 和 [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(CO(2)R)=C(CO(2)R)PPh(2))(CO)] [R = CH(3), (6), R = (t)Bu, (7)] 通过与甲基丙炔酸酯 (HC[三重键]CCO(2)CH(3)) 或甲基 2-丁炔酸酯 (CH(3)C[三重键]CCO(2)CH(3)) 与二甲基 2-丁炔二酸酯 [(CH(3) O(2)C)C[三重键]C(CO(2)CH(3))] 或二(叔丁基) 2-丁炔二酸酯 [((t)BuO(2)C)C[三重键]C(CO(2)(t)Bu)] 的反应成功合成。然而，与更富电子的炔烃的反应未观察到。与甲基丙炔酸酯、甲基 2-丁炔酸酯 (MeC[三重键]CCO(2)Me) 或二(叔丁基) 2-丁炔二酸酯反应，得到了令人惊讶的新的异钽杂环配合物 [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(=NXylyl)C(R(1))=C(R(2))PPh(2)-kappa(1)-P)] [R(1) = H, R(2) = CO(2)Me (8); R(1) = Me, R(2) = CO(2)Me (9); R(1) = CO(2)(t)Bu, R(2) = CO(2)(t)Bu (10)]。最后，膦配合物和与苯乙炔 (PhC[三重键]CH) 反应得到新的二苯基膦烯基钽衍生物 [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(eta(1)-C-C(C(6)H(5))=C(H)PPh(2)(CNR)] [R = xylyl (11), Cy (12)]。所有这些化合物都通过 NMR 光谱进行了表征，并通过单晶 X 射线衍射研究确定了的分子结构。还通过密度泛函理论 (DFT) 计算对膦配合物中 Nb-P 键的炔烃插入进行了理论研究。
