| Abstrakt: |
Employing time-resolved IR spectroscopy, we have demonstrated that, following photolysis of [Cp*Cr(CO)2]2 (1) in n-heptane, the only initial photoproduct is the triply bridged CO-loss intermediate Cp*Cr(μ-CO)3CrCp* (4). Two bridging ν(CO) bands are observed, resulting from the splitting of the e mode of 4, which leads to the conclusion that the CO bridging groups are asymmetric. The rate of the back reaction of 4 with CO has been measured (k2 = 5.2 (±0.5) × 107 M-1 s-1), and this is 1000 times faster than the rate of the analogous back reaction of CO with CpFe(μ-CO)3FeCp. Moreover, unlike many CO-loss intermediates, there is no reaction of 4 with PPh3. The rate of reaction of 4 with THF, to produce Cp*2Cr2(CO)3(THF) (6), has been estimated (k2 = 1.6 (±0.2) × 108 M-1 s-1). |
