카르벤-올레핀-전이금속착물들[$(CO)_4M=CHX(CH_2=CH_2)$] (X: $OCH_3,;NHCH_3,;SCH_3$, M: C, Mo, W)의 형태에 대하여 확장된 Huckel 방법으로 계산하여 연구하였다. $d^6$ 전이금속 8면체 착물에서는 두 개의 인자 즉 금속에서 리간드로의 역제공과 리간드-리간드 상호작용이 안정한 형태를 결정해 준다는 사실이 밝혀졌지만 카르벤에 $pi$-전자를 수용하는 리간드와 $pi$-전자를 주는 기가 배위되어 있을 때 리간드-리간드 상호작용이 우세하므로 착물이 형태를 결정해 주는 주요한 인자라고 예측된다.
The conformations of several carbene-olefin-transition metal complexes[$(CO)_4M$-(CHX)olefin] (X: $OCH_3,;NHCH_3,;SCH_3$, M: C, Mo, W) have been studied by means of Extend Huckel calculations. In the case of $d^6$ transition metal octahedral complexes, it is shown that the two main factors which determine the optimal conformation are metal-to-ligand back-donation and direct ligand-ligand interaction at the metal, but the ligand-ligand interaction dominates the situation for a metal that is coordinated to $pi$ acceptor ligands and to $pi$ donor group on the carbene. The relative amounts of both factors depend strongly on the electronic nature of the ligands at the metal. The greater electron donating ability of nitrogen stabilizes amino-substituted carbene complexes compared with their alkoxyl substituted analogues. This interaction is optimal when the $pi$ systems of the carbene and olefin are coplanar. The introduction of the $pi$ donor group on the carbene carbon increases also the importance of the ligand-ligand interaction.
