高等学校化学学报

高等学校化学学报 ›› 1995, Vol. 16 ›› Issue (3): 329.

• 论文 •    下一篇

铬的羰基络合物及其碳炔衍生物中铬原子的共价

义祥辉, 黎乐民, 徐光宪   

  1. 北京大学化学系, 北京 100871
  • 收稿日期:1994-06-08 修回日期:1994-10-14 出版日期:1995-03-24 发布日期:1995-03-24
  • 通讯作者: 徐光宪
  • 作者简介:义祥辉,男,36岁,副教授.
  • 基金资助:

    国家自然科学基金

Covalendes of Cr in Cr(CO)6and(CO)4ICrCCH3

YI Xiang-Hui, LI Le-Min, XU Guang-Xian   

  1. Department of Chemistry, Peking University, Beijing 100871
  • Received:1994-06-08 Revised:1994-10-14 Online:1995-03-24 Published:1995-03-24

PDF (PC)

被引次数

4

摘要： 用DV-Xα方法和自然轨道法研究了Cr(CO)6和(CO)4ICrCCH3的电子结构和成键情况,并根据共价新定义讨论了其中铬原子的共价。结果表明:在(CO)4ICrCCH3中,Cr-Ccarbyne之间存在三重键,但其中只有σ键定域在Cr-Ccarbyne两原子之间,而两个π键已部分离域到各CO上;另外,中心铬原子上的价电子未能反馈到Ccarbyne上。两个因素同时作用,结果使Ccarbyne上的电荷密度较同一分子中的CCO和CMe小。这一计算结果从理论上解释了该分子的13CNMR谱化学位移Ccarbyne大于CCO和CMe的原因。由于在Cr(CO)6和(CO)4ICrCCH3分子中铬原子均接受了12个有效共享成键电子,根据共价新定义,铬原子共价均为12.

关键词: 共价, 自然键轨道法, 铬, 羰基络合物, 碳炔

Abstract: The electronic structures and bonding of Cr(CO)6 and(CO)4 ICrCCH3 were studied with the methods of DV-Xa SCC and natural bond orbitals(NBOs),and then the covalencies of Cr in these two compounds were discussed on the basis of the new difinition of covalence proposed by one of the authors.The results show that there exists a Cr-Ccarbyne triple bond in which σ bond is localized and two π bonds are partially delocalized to carbonyls;on the other hand,there is no back donation of charges from the central chromium atom to the carbyne carbon atom,so the carbyne carbon possesses lower electronic density than carbonyl carbon and methyl carbon in the same molecule,which is consistent with 13CNMR spectrum. The covalencies of Cr in both ompounds are 12.

Key words: Covalence, Natural bond orbitals(NBOs), Chromium, Carbonyl complex, Carbyne

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