采用从头算分子轨道法对锥型硼烷B5H10X(X=Be-,B,C+,BeH,CH2 +,B2 -,C-,N,O+,BH-,CH,NH+和OH2 +)进行了研究,结果表明 ,端氢和桥氢原子与帽基原子相对位置的变化是由帽基原子和环原子轨道的弥散程度及环的尺寸效应共同决定的.端氢原子对桥氢原子的空间位置有着制约作用.当环原子数达到5个时,Br-Ht 键弯向帽基方向,而Br Hb Br 键则远离帽基.所有几何参数及总能量均选用MP2/6 31G 、HF/D95V和MP2/D95V三种方法进行优化. Cone boranes B5H10X (X = Be-, B, C +, BeH, CH2 +, B2-, C-, N, O +, BH-, CH, NH + and OH2 +) were studied using ab initio molecular orbital methods The results show that the change of the relative positions between the terminal hydrogen atoms and the hydrogen atoms in the bridge is determined by the diffusion degree of the cap atom and the ring atom orbit and the size effect of the ring. When the number of ring atoms reaches 5, the Br-Ht bonds bend toward the cap and the Br Hb Br bonds away from the cap. All geometric parameters and total energies are selected from MP2 / 6 31G, HF / D95V and MP2 / D95V three ways to optimize.