Interplay between Two-Electron and Four-Electron Donor Carbonyl Groups in Oxophilic Metal Systems: Highly Unsaturated Divanadocene Carbonyls
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- 作者：Qian-shu Li ; Xiuhui Zhang ; Yaoming Xie ; R. Bruce King ; and ; Henry F. Schaefer III
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：March 21, 2007
- 年：2007
- 卷：129
- 期：11
- 页码：3433 - 3443
- 全文大小：876K
- 年卷期：v.129,no.11(March 21, 2007)
- ISSN：1520-5126
文摘
The divanadocene carbonyls Cp2V2(CO)n (n = 5, 4, 3, 2, 1; Cp = 
5-C5H5) have been studiedby density functional theory using the B3LYP and BP86 functionals. The global minimum for Cp2V2(CO)5with a V
V distance of 2.452 Å (BP86) is essentially the same as the structure of the known Cp2V2(CO)5determined by X-ray diffraction. The global minimum of Cp2V2(CO)4 is a triplet electronic state with a VVdistance of 2.444 Å (BP86). However, slightly higher energy singlet Cp2V2(CO)4 structures are found eitherwith a VV distance of 2.547 Å (BP86) and one four-electron donor bridging CO group or with a V
Vdistance of 2.313 Å (BP86) and all two-electron donor bridging CO groups. Comparison is made betweenCp2V2(CO)3 and the recently synthesized quintuply bonded RCrCrR (R = bulky aryl group) complexes ofPower and co-workers. Four-electron donor bridging carbonyl groups become more prevalent upon furtherdecarbonylation, leading ultimately to three singlet Cp2V2(2-
-CO)2 isomers as well as triplet, quintet, andseptet structures of Cp2V2(CO) with extremely low 
(CO) frequencies around 1400 cm-1. Our mostremarkable structural finding is the extremely short vanadium-vanadium distance (1.80 Å, BP86) predictedfor the singlet structure of Cp2V2(CO).
5-C5H5) have been studiedby density functional theory using the B3LYP and BP86 functionals. The global minimum for Cp2V2(CO)5with a VV distance of 2.452 Å (BP86) is essentially the same as the structure of the known Cp2V2(CO)5determined by X-ray diffraction. The global minimum of Cp2V2(CO)4 is a triplet electronic state with a VVdistance of 2.444 Å (BP86). However, slightly higher energy singlet Cp2V2(CO)4 structures are found eitherwith a VV distance of 2.547 Å (BP86) and one four-electron donor bridging CO group or with a VVdistance of 2.313 Å (BP86) and all two-electron donor bridging CO groups. Comparison is made betweenCp2V2(CO)3 and the recently synthesized quintuply bonded RCrCrR (R = bulky aryl group) complexes ofPower and co-workers. Four-electron donor bridging carbonyl groups become more prevalent upon furtherdecarbonylation, leading ultimately to three singlet Cp2V2(2--CO)2 isomers as well as triplet, quintet, andseptet structures of Cp2V2(CO) with extremely low (CO) frequencies around 1400 cm-1. Our mostremarkable structural finding is the extremely short vanadium-vanadium distance (1.80 Å, BP86) predictedfor the singlet structure of Cp2V2(CO).