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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 structure and properties of (Me_2InN_3) _n (n = 1 ~ 3) clusters have been studied by using the density functional theory B3LYP / Lanl2dz method. The results show that the structures and properties of (Me_2InN_3) _n ) Are the ring structures formed by the connection of azido α-N and In atoms in different sub-systems. The trimer’s torsional conformation is 3.76 kJ / mol lower than that of the chair conformation. The geometrical parameters showed that the bond length of Nα-In, Nα-Nβ, Nβ-Nγ and In-C bonds varied with the degree of polymerization. The In-Nα-In bond in the cyclic configuration was always higher than that of Nα-In-Nα Angle.At the same time, the vibration frequencies of all the optimized configurations were calculated and their IR spectra were assigned.According to the thermodynamic calculation, it was found that the torsional conformation of the trimer is more stable than the chair-type conformation.From the 298.2 K enthalpy change and the Gibbs free energy It turns out that the monomer dimer and trimer are thermodynamically favored whereas the Gibbs free energy of the dimer trimer becomes positive.