An investigation into the photochemical reactions of M(eta(5)-C5H5)(CO)(4)and M(eta(5)-C9H7)(CO)(4) (M = Nb or Ta) with H-2 and N-2 in polyethylene matrices and liquid xenon at low temperature

The photolysis of MCp'(CO)(4) (Cp'=Cp or indenyl; M=Nb or Ta) in polyethyle ne (PE) matrices at low temperature under a high pressure of reactant gas l ed to formation of a wide range of photoproducts. Under an inert atmosphere (helium), NbCp'(CO)(3) and NbCp'(CO)(2) are observed following irradiation of the parent tetracarbonyl. However, only TaCp'(CO)(3) is observed for th e analogous reactions of the corresponding tantalum compounds. Similarly, N bCp'(CO)(3)(N-2) and NbCp'(CO)(2)(N-2)(2) are seen following irradiation of NbCp'(CO)(4) under a high pressure of N-2, whereas only TaCp'(CO)(3)(N-2) was observed following irradiation of TaCp'(CO)(4). Under hydrogen, the cla ssical dihydride TaCp'(CO)(3)H-2 is formed following irradiation of TaCp'(C O)(4). The non-classical dihydrogen complex Nb(C9H7)(CO)(3)(eta (2)-H-2) is formed following irradiation of Nb(C9H7)(CO)(4). NbCp(CO)(4) forms both th e classical hydride and non-classical dihydrogen complex. Using a high pres sure-low temperature cell, the thermal reaction of TaCp'(CO)(3)(N-2) with h ydrogen to form TaCp'(CO)(3)H-2 was observed. Preliminary room temperature studies suggest that Ta(C9H7)(CO)(3)H-2 is ca. 50 times more reactive than TaCp(CO)(3)H-2 in PE.