- 作者: 林秀美 ; 許火順 ; 王志傑 ; 支志明 ; 王瑜
- 作者服務機構: 台灣大學化學系
- 中文摘要: The electron density distribution of a chromium(IV)-oxo complex, [Cr/sup IV/(O)(TMP)] (TMP = 5,10,15,20-tetrakis-p-methoxyphenyl porphyrin), is investigated by molecular orbital calculation. The molecular and crystal structure of the compound is studied by x-ray diffraction. It belongs to the space group I2, Z = 2, a = 14.979(4).ANG., b = 9.752(3), c = 15.605(3) .ANG., .beta. = 100.97(2).degree., V = 2238(1) .ANG./sup 3/, Mo K.alpha. Radiation .lambda.= 0.7107.ANG., R = 4.9%, Rw = 3.5% for 3575 observed reflections. Cr is five-coordinated in a square pyramidal fashion with the Cr atom located 0.42 .ANG. toward the oxo-ligand. Deformation density maps are derived from the single point molecular orbital calculation on the basis of HF and DFT(density functional theory) calculations. The accumulation of deformation density along the C-H, C-C, C-N and C-O bonds in the porphyrin ligand is well represented. The asphericity in electron density around the Cr ion is clearly demonstrated. Natural bond orbital analysis (NBO) reveals that the Cr-O/sub oxo/ is actually a triple-bond character (.sigma./sup 2/.pi./sup 4/) and the four N of pyrrole serves as a .sigma.-donor to Cr. The Cr-N/sub pyrrole/ bond is essentially a dative bond. d- Orbital populations of Cr derived from both calculations are in good agreement with each other. Planar d/sub .pi./-orbital is the most populated, which is in accord with the prediction from crystal field theory. Detail bond characterization of the Cr -L multiple bond is discussed.
- 英文摘要: --
- 中文關鍵字: Electron Density; Cr-O/Sub Oxo/ Bond; Crystal Structure
- 英文關鍵字: 電子密度;Cr-O/sub oxo/鏈;晶體結構