有机金属化合物中二级化学键的理论研究（I）──β－氯乙烯基氯化汞中的共轭键及二级化学键  

Theoretical Study on Secondary Bond in Organo-Metallic Compound(I)──The Conjugated Bond and Secondary Bond in β-Chlorovinyl Mercury Chloride

作　　者：赖城明[1] 袁满雪[1] 唐珺[1] 崔崇威[1] 罗新才[1] 

机构地区：[1]南开大学化学系

出　　处：《高等学校化学学报》1995年第6期877-880,共4页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金

摘　　要：根据实验数据分析，指出标题分子中存在着包括Ｈｇ的空６ｐｚ轨道在内的共轭键。根据顺、反式分子间性质的差异，说明在顺式分子中能形成弱的二级化学键，而反式则不能形成。并应用ＭＮＤＯ方法对分子进行计算，结果证明上述结论正确。According to the analysis of experimantal data, we found that :(l)crystal structure indicates that the title trans-molecule has a plane structure; (2)The vector sum of bond-moment of individual single, double and triple bond can not be used to explain the molecular dipole moment; (3)Raman spectrum misses characteristic frequency of vibration of double or triple bond; (4)Ultra-violet absorption λmax shifts toward red; (5) C-Cl bond in chloroethylene molecule and C Hg bonds in diphenyl mercury molecule are proved to be conjugated. Thus we infer there exists a conjugated bond in the title molecule including the vacant 6pz orbital of mercury. In order to further study the formation of this conjugated bond,we applied MNDO semi-empirical molecular orbital calculation to these cis- and transmolecules.The results show that in each molecule, there exist someπmolecular orbitals involving empty 6pz orbital of mercury atom, the C Hg bond has about 0.1 π-bond order,thus it proves the vacant 6pz orbital of mercury indeed participates in the formation of conjugated system.By comparison of the difference of properties of cis- with trans- compound, we found that the cis- one has a higher melting poin,more negative heat of formation and the heat of elimination of C2H2 from this molecule, less quantity in isotope exchange,its decompostion in alcohol is more slow, and its 1,4-reaction is more difficult to take place.In view of above distiction it shows that cis-molecule is more stable than trans-one. Thus we assumed that in cis-molecule there is a weak secondary chemical bond which located in the plane of molecule,essentially it is a weak three centers with four electrons delocalization bond. MNDO calculation supports this viewpoint.In , in l964, the author already predicted the existence of this bond in abovemolecul.

关 键 词：氯乙烯基 氯化汞 共轭键 二级化学键 MNDO 

分 类 号：O627.23[理学—有机化学] O641.2[理学—化学]