摘要
采用密度泛函理论B3LYP/Lanl2dz方法,计算研究了(Me_2InN_3)_n(n=1～3)簇合物的结构和性质.研究表明,环状多聚体(Me_2InN_3)_n(n=2～3)的优化构型均为由不同子体系的叠氮基α-N和In原子相连形成的环状结构.三聚体的船扭式构象比椅式构象的能量低3.76 kJ/mol.比较分析几何参数后发现N_α-In、N_α-N_β、N_β-N_γ和In-C键键长随聚合度的变化趋势,环状构型中In-N_α-In键角总是较N_α-In-N_α键角大.同时对所有优化构型进行振动频率计算,并对其IR谱进行归属.通过热力学计算,发现三聚体的船扭式构象较椅式构象稳定.由298.2 K焓变和Gibbs自由能变可知,单体形成二聚体和三聚体在热力学上是有利的,而由二聚体形成三聚体的Gibbs自由能则变为正.
The （MezInN3）. （n= 1-3） clusters were optimized to obtain the structures and properties at the DFT-B3LYP/Lanl2dz level. The optimized clusters （Me2InN3）. （n= 2-3） all possess cyclic structure formed by In atoms bridged by the a-nitrogen of the azide groups. The twist-boat conformation lies 3.76 kJ/mol lower in energies than the chair isomer for the trimers. Comparisons of the structural parameters reveal the trends in the Na-In, Na-Nβ, Nβ-Nr and In-C bond lengths with oligomerization degree n. The In-N-In angles in the cyclic oligomers are consistently larger than the Na-In-No ones. Frequency calculations were carried out on each optimized structure, and their IR spectra were assigned. Thermodynamic properties demonstrate that twist-boat conformation is preferred over chair conformation in the gas phase. The dimerization and trimerization are thermodynamically favorable by the enthalpies and the Gibbs energies at 298.2 K, however, the Gibbs energies of dimer-trimer reorganizations are positive.
出处
《南开大学学报（自然科学版）》
CAS
CSCD
北大核心
2010年第4期48-54,共7页
Acta Scientiarum Naturalium Universitatis Nankaiensis
基金
China Postdoctoral Science Foundation(20070410335)
Jiangsu Postdoctoral Research Funds (0701024C)
International cooperation Program for Excellent Lecturers by Shandong Provincial Education Department
