摘要
The cyclopentadienylmolybdenum carbonyls Cp 2Mo 2(CO) n (Cp = n 5-C 5H 5; n = 6-1) have been studied by density functional theory. The two lowest energy structures predicted for Cp 2Mo 2(CO) 6 lie within 4 kcal/mol of each other. Both have Mo-Mo single bonds of lengths 3.2-3.3 A° with all terminal carbonyl groups and correspond to stable compounds structurally characterized by X-ray diffraction. Similarly, the lowest energy structure predicted for Cp 2Mo 2(CO) 4 has a formal Mo Mo triple bond of length ̃2.5 A° with four weakly semibridging carbonyl groups also corresponding to a stable compound structurally characterized by X-ray diffraction. The pentacarbonyl Cp 2Mo 2(CO) 5, which is not known experimentally as a stable compound but only as a transient intermediate, is shown to have a structure with one symmetrical bridging two-electron donor and four terminal carbonyl groups as well as a formal Mo Mo double bond. Furthermore, Cp 2Mo 2(CO) 5 is predicted to be thermodynamically unstable with respect to disproportionation into Cp 2Mo 2(CO) 6 + Cp 2Mo 2(CO) 4. The lowest energy structure for Cp 2Mo 2(CO) 3 is a triplet with a formal MotMo triple bond. A higher energy singlet structure with one four-electrondonor bridging carbonyl group is also found for Cp 2Mo 2(CO) 3. The MotMo bond distances in the lowest energy more highly unsaturated Cp 2Mo 2(CO) 2 and Cp 2Mo 2(CO) structures suggest formal bond orders no higher than 3 in the lowest energy structures and thus metal atoms with less than the favored 18-electron configurations.
| 源语言 | 英语 |
|---|---|
| 页(从-至) | 2818-2829 |
| 页数 | 12 |
| 期刊 | Organometallics |
| 卷 | 28 |
| 期 | 9 |
| DOI | |
| 出版状态 | 已出版 - 11 5月 2009 |
学术指纹
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