（NPX2）3（X=F,Cl,Br,I）的几何构型和振动频率的MNDO研究

运用ＭＮＤＯ方法对标题化合物的几何构型和振动频率进行了理论计算，计算出来的结构参数与晶体Ｘ－射线实验数据一致；计算出来的捱劝频率与红外和拉曼光谱基本一致，最后，计算得出目前在实验上尚未报道的（ＮＰＩ２）３的上述两个方面的理论数据。

MNDO STUDY ON GEOMETRY AND VIBRATIONAL FREQUENCIES FOR HOMOGENEOUSLY SUBSTITUTED HEXAHALOCYCLOTRIPHOSPHAZENES

Geometry and vibrational frequencies corresponding to the force field are calculated for the title species with MNDO method.The calculated structural parameters agree well with the X ray experimental data.The MNDO calculation of the harmonic force field is in reasonable agreement with the experimental frequencies.By the use of correlating the experimental frequencies with the calculated net atomic charges together with the semi empirical force field calculations,a set of frequencies are predicted for hexaiodocyclotriphosphazene for which no observation of frequencies are reported.