Water-trimer clusters as nucleophilic reagents in hydrolyses of substrates for metal–alkoxides – a computational study
Water-trimer clusters as nucleophilic reagents in hydrolyses of substrates for metal–alkoxides – a computational study
复制标题
水三聚体簇作为金属醇盐底物水解中的亲核试剂——一项计算研究
DOI：
10.1016/s0022-3093(01)00808-0
复制
发表时间：
2001
影响因子：
3.5
通讯作者：
S. Yamabe
中科院分区：
文献类型：
--
作者：
S. Okumoto;S. Yamabe
进行密度泛函理论计算以模拟八种金属甲醇盐的水解路径，M（OMe）nM=Al和Ga（n=3），M=Si、Ge、Ti和Zr（n=4），M=V和Nb（n=5）。这些路径是溶胶-凝胶过程的初始步骤，并被发现由基板M（OMe）水三聚体簇。无应变氢键网络在过渡态（TS）处构建，并且可以引起容易的键交换，即，M-O键的断裂以及O-H共价键和O-OH氢键的形成和转换。TS具有两性离子特征，并且基本上通过溶剂效应而稳定。根据前线轨道理论，计算的活化能与最低未占分子轨道的能量相关良好。
Density-functional-theory calculations were performed to simulate hydrolysis paths of eight metal–methoxides, M(OMe)nM=Al and Ga for n=3, M=Si, Ge, Ti, and Zr for n=4 and M=V and Nb for n=5. Those paths are initial steps of the sol–gel process and were found to consist of substrates M(OMe)nand water-trimer clusters. Strain-free hydrogen-bond networks are constructed at transition states (TSs) and may cause ready bond interchanges, i.e., M–O bond cleavage and formation and switch of O–H covalent and O⋯H hydrogen bonds. TSs have zwitterionic characters and are stabilized substantially by the solvent effect. The calculated activation energies correlate well with energies of the lowest unoccupied molecular orbitals according to the frontier-orbital theory.