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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 53, Number 3
JKCSEZ 53(3)
June 20, 2009 

 
Title
Electronic Structure and Chemical Bonding of La7Os4C9

La7Os4C9의 전자구조와 화학결합
Author
Dae Bok Kang*

강대복*
Keywords
Ternary transition metal carbide, Electronic structure, Extended Huckel calculations, FMO analysis , Ternary transition metal carbide, Electronic structure, Extended Huckel calculations, FMO analysis
Abstract
고체 화합물 La7Os4C9 속에 있는 [Os4C9]21? 사슬의 전자구조와 화학결합을 extended Huckel 계산 결과에 의해서 논의하였다. 탄소 원자는 물론 (C2)2? 분자의 결합 특성은 비교적 큰 Os-C 상호작용을 나 타내었고 특히 (C2)2? 분자의 결합길이 증가는 Fermi level 바로 아래에 Os-C2(1 πg) 결합 밴드의 존재로 인 해서 반결합 1πg 오비탈에 부분적인 전자점유가 일어나기 때문인 것으로 해석된다.

In the recently synthesized rare earth transition metal carbide La7Os4C9 one finds one-dimensional organometallic [Os4C9]21? polymers embedded in a La3+ ionic matrix. The electronic structure of the polymeric [Os4C9]21? chain was investigated by density of states (DOS) and crystal orbital overlap population (COOP), using the extended Huckel algorithm. A fragment molecular orbital analysis is used to study the bonding characteristics of the C2 units in La7Os4C9 containing C2 units and single C atoms as well. The title compound contains partially filled Os and carbon bands leading to metallic conductivity. As the observed distances already indicated, the calculations show extensive Os-C interactions. The C-C bond distance in the diatomic C2 units (dC-C=131 pm) in the solid is significantly increased relative to C22? or acetylene, because antibonding 1πg orbitals are partially filled by the Os-C2(1πg) bonding contribution found at and below the Fermi level.

Page
266 - 271
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