Syntheses and Structures of Asymmetric Bis(silyl) Niobocene Hydrides

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• 作者：Konstantin Yu. Dorogov ; Muhammed Yousufuddin ; Nam-Nhat Ho ; Andrei V. Churakov ; Lyudmila G. Kuzmina ; Arthur J. Schultz ; Sax A. Mason ; Judith A. K. Howard ; Dmitry A. Lemenovskii ; Robert Bau ; Georgii I. N
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：January 8, 2007
• 年：2007
• 卷：46
• 期：1
• 页码：147 - 160
• 全文大小：271K
• 年卷期：v.46,no.1(January 8, 2007)
• ISSN：1520-510X

文摘

This paper deals with the preparation and structural investigation of asymmetric bis(silyl) niobocene hydrides, Cp₂Nb(SiHMe₂)(H)(SiXMe₂) (2; X = F (a), Cl (b), Br (c), I (d)) and Cp₂Nb(SiXMe₂)(H)(SiYMe₂) (X,Y= F-I; X Y).Complexes 2a-d were prepared by selective electrophilic activation of the Si-H bond in Cp₂Nb(SiHMe₂)₂(H). TheCp₂Nb(SiXMe₂)(H)(SiYMe₂) complexes were prepared by electrophilic activation of the Si-H bond in 2a-d and, insome cases, by electrophilic exchange of the X halides in Cp₂Nb(SiXMe₂)₂(H) (1) for other halides, Y. The structuresof complexes 2b and 2c have been studied by X-ray and neutron diffraction (ND). The ND results unequivocallyestablished that the hydride ligand in 2c is shifted toward the SiBrMe₂ ligand and that in 2b is positioned symmetricallybetween two nonequivalent silyl groups, with the H···SiClMe₂ distance being shorter because of the shorter Nb-SiClMe₂ bond length. Analysis of the X-ray structures of complexes 2a-d and complexes Cp₂Nb(SiXMe₂)(H)(SiYMe₂) shows that the largest structural distortions are observed for the silyl groups substituted by heavy halogenatoms. These trends are rationalized in terms of stronger interligand hypervalent interactions (IHI) Nb-H···Si-Xfor heavy atoms X from Group 7.