Abstract
The reaction of [Cp'Nb-2(Te-2)H] (1) (Cp' = tBuC(5)H(4)) with [Fe-2(CO)(9)] gives [{Cp'2NbH(Te)(2)}Fe-2(CO)(6)](2). Compound 2 reacts with [Cr(CO)(5)THF] to give [{Cp'2NbH(Te)(2)Fe-2(CO)(6)}Cr-.(CO)(5)] (3) in nearly quantitative yield. The crystal structure of 3 reveals that the Fe-2(CO)(6) unit in this complex (and consequently in 2) is inserted in a perpendicular manner into the original NbTe2 ...
Abstract
The reaction of [Cp'Nb-2(Te-2)H] (1) (Cp' = tBuC(5)H(4)) with [Fe-2(CO)(9)] gives [{Cp'2NbH(Te)(2)}Fe-2(CO)(6)](2). Compound 2 reacts with [Cr(CO)(5)THF] to give [{Cp'2NbH(Te)(2)Fe-2(CO)(6)}Cr-.(CO)(5)] (3) in nearly quantitative yield. The crystal structure of 3 reveals that the Fe-2(CO)(6) unit in this complex (and consequently in 2) is inserted in a perpendicular manner into the original NbTe2 moiety of 1, while the incoming Cr(CO)(5) fragment is attached at the central Te atom and in vicinity (vic) to the Nb-H moiety. H-1 NMR investigations of solutions of 3 at -80 degreesC show that only the sterically crowded vic-3 has been separated by recrystallization. At -60 degreesC a rapid exchange is observed for the ring protons, which may be explained by rotation of the Cp' rings around the Cp'-Nb axes. Above 0 degreesC an additional Set Of C5H4, tBu, and NbH resonances appears, which may be assigned to migration of the Cr(CO)(5) fragment from the central to the lateral Te atom. The resulting opp-3 is in a 55:45 equilibrium with vic-3 at 20 degreesC.
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