Unusual Structure and Reactivity of the Photogenerated Intermediate Cp*Cr(-CO)3CrCp* (Cp* = 
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- 作者：Ian G. Virrels ; Trevor F. Nolan ; Michael W. George ; and James J. Turner
- 刊名：Organometallics
- 出版年：1997
- 出版时间：December 23, 1997
- 年：1997
- 卷：16
- 期：26
- 页码：5879 - 5883
- 全文大小：168K
- 年卷期：v.16,no.26(December 23, 1997)
- ISSN：1520-6041
文摘
Employing time-resolved IR spectroscopy, we have demonstratedthat, following photolysisof [Cp*Cr(CO)2]2 (1) inn-heptane, the only initial photoproduct is the triplybridged CO-loss intermediate Cp*Cr(
f">-CO)3CrCp* (4).Two bridging 
fchars/nu.gif" BORDER=0 >(CO) bands are observed,resultingfrom the splitting of the e' mode of 4, which leads to theconclusion that the CO bridginggroups are asymmetric. The rate of the back reaction of4 with CO has been measured(k2= 5.2 (±0.5) × 107 M-1s-1), and this is 1000 times faster than the rate of theanalogousback reaction of CO with CpFe(f">-CO)3FeCp. Moreover,unlike many CO-loss intermediates,there is no reaction of 4 with PPh3. Therate of reaction of 4 with THF, to produceCp*2Cr2(CO)3(THF) (6),has been estimated (k2 = 1.6 (±0.2) ×108 M-1 s-1).
f">-CO)3CrCp* (4).Two bridging fchars/nu.gif" BORDER=0 >(CO) bands are observed,resultingfrom the splitting of the e' mode of 4, which leads to theconclusion that the CO bridginggroups are asymmetric. The rate of the back reaction of4 with CO has been measured(k2= 5.2 (±0.5) × 107 M-1s-1), and this is 1000 times faster than the rate of theanalogousback reaction of CO with CpFe(f">-CO)3FeCp. Moreover,unlike many CO-loss intermediates,there is no reaction of 4 with PPh3. Therate of reaction of 4 with THF, to produceCp*2Cr2(CO)3(THF) (6),has been estimated (k2 = 1.6 (±0.2) ×108 M-1 s-1).