Time resolved step-scan FTIR spectroscopy (s2-FTIR) has been used to characterise MCpâ²(CO)3L (Cpâ²Â = Cp or indenyl (η5-C9H7); M = Nb or Ta; L = n-heptane, H2 or N2) in solution at room temperature. TaCpâ²(CO)4 formed the classical dihydrides, TaCpâ²(CO)3H2 upon irradiation in n-heptane saturated with H2. However, photolysis of Nb(η5-C9H7)(CO)4 under the same conditions led to the non-classical complex, Nb(η5-C9H7)(CO)3(η2-H2), whereas irradiation of NbCp(CO)4 resulted in both NbCp(CO)3H2 and NbCp(CO)3(η2-H2). Photolysis of MCpâ²(CO)4 in n-heptane saturated with N2 resulted in formation of MCpâ²(CO)3(N2) in all cases. No evidence for disubstitution of these complexes was obtained in these s2-FTIR experiments. The rate constants for the reaction of M(η5-C9H7)(CO)3(n-C7H16) with CO, H2 and N2 have been determined. Comparison of these rate constants with those obtained for the analogous cyclopentadienyl complexes showed that the indenyl complexes are more reactive (ca. 10 times). Additionally, the Nb(η5-C9H7)(CO)3(L) (L = η2-H2 or N2) complexes were found to be less stable (ca. 20â30 times) than NbCp(CO)3(L), and Ta(η5-C9H7)(CO)3(N2) was more reactive (ca. 25 times) than TaCp(CO)3(N2).
时间分辨阶跃扫描傅立叶变换红外光谱(s2-FTIR)被用来描述室温下溶液中 MCpâ²(CO)3L (Cpâ²Â = Cp 或
茚基(δ-5-
C9H7);MÂ =Â Nb 或 Ta;LÂ =Â
正庚烷、H2 或 N2)的特性。TaCpâ²(CO)4在充满 H2 的
正庚烷中经辐照后形成经典的二
氢化物 TaCpâ²(CO)3H2。然而,在相同条件下,Nb(δ-5- )(CO)4 光解会产生非经典复合物 Nb(δ-5- )(CO)3(δ-2-H2),而照射 NbCp(CO)4 则会产生 NbCp(CO)3H2 和 NbCp(CO)3(δ-2-H2)。在 N2 饱和的
正庚烷中光解 MCpâ²(CO)4,在所有情况下都会生成 MCpâ²(CO)3(N2)。在这些 s2-FTIR 实验中没有发现这些复合物发生置换的迹象。测定了 M(δ-5- )(CO)3(n-
C7H16)与 CO、H2 和 N2 反应的速率常数。将这些速率常数与类似的
环戊二烯络合物的速率常数进行比较后发现,
茚基络合物的反应活性更高(约为
环戊二烯络合物的 10 倍)。此外,还发现 Nb(δ-5- )(CO)3(L)(LÂ = Â δ-2-H2 或 N2)络合物的稳定性比 NbCp(CO)3(L)低(约 20-30 倍),而 Ta(δ-5- )(CO)3(N2)的反应性比 TaCp(CO)3(N2)高(约 25 倍)。