MCSCF Study of Multiple Bonding between Ti and the Main-Group Elements C, Si, N, and P

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• 作者：Gyusung Chung and Mark S. Gordon
• 刊名：Organometallics
• 出版年：2003
• 出版时间：January 6, 2003
• 年：2003
• 卷：22
• 期：1
• 页码：42 - 46
• 全文大小：74K
• 年卷期：v.22,no.1(January 6, 2003)
• ISSN：1520-6041

文摘

The nature of the multiple bonding of H₂Ti=EH₂ (E = C, Si) and H₂Ti=EH (E = N, P)molecules has been investigated with the multiconfiguration SCF (MCSCF) method. It isshown that the Ti-C and Ti-P bond lengths decrease with bond rotation, whereas theTi-Si bond length increases. MCSCF geometry optimization shows that Ti-N has triple-bond character with a linear Ti-N-H bond angle that results from strong back-bondingfrom the N lone pair into the empty Ti d orbitals. The rotation barrier and bond dissociationenergy for Ti=E are estimated with the MCSCF + multireference second-order perturbationtheory (MRMP2) method. The singlet rotation barriers in Ti=C, Ti=Si, and Ti=P areestimated to be 15.9, 8.6, and 9.3 kcal/mol, respectively. The Ti=C and Ti=Si bonddissociation energies are estimated to be 83.4 and 56.9 kcal/mol, respectively. The TiNtriple-bond energy is about 30 kcal/mol larger than that of the carbon species, whereas theenergy of the Ti=P bond is about 8 kcal/mol smaller than that of the silicon species.