Time resolved step-scan FTIR spectroscopy (s2-FTIR) has been used to characterise MCp′(CO)3L (Cp′ = Cp or indenyl (η5-C9H7); M = Nb or Ta; L = n-heptane, H2 or N2) in solution at room temperature. TaCp′(CO)4 formed the classical dihydrides, TaCp′(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(η 2-H2), whereas irradiation of NbCp(CO)4 resulted in both NbCp(CO)3H2 and NbCp(CO)3(η2-H2). Photolysis of MCp′(CO)4 in n-heptane saturated with N2 resulted in formation of MCp′(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-C 7H16) 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. 20-30 times) than NbCp(CO)3(L), and Ta(η5-C9H7)(CO)3(N 2) was more reactive (ca. 25 times) than TaCp(CO)3(N2).
|Number of pages||7|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 2001|
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