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Binuclear cyclopentadienylmolybdenum carbonyl derivatives: Where is the missing modMo Double-Bonded species Cp 2Mo 2(CO) 5?

  • Zhang Xiuhui
  • , Li Qian-shu*
  • , Ge Maofa
  • , Xie Yaoming
  • , R. Bruce King
  • , Henry F. Schaefer
  • *此作品的通讯作者
  • South China Normal University
  • Beijing Institute of Technology
  • CAS - Institute of Chemistry
  • University of Georgia

科研成果: 期刊稿件文章同行评审

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
28
9
DOI
出版状态已出版 - 11 5月 2009

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