C_(28)X_4(X=H、F、Cl、Br及I)球簇分子之理論研究

Theoretical Study of C_(28)X_4 (X =H, F, CI, Br and I) Cluster Molecules

孫光中(K. C. Sun) ； 陳成(C. Chen)

《化學》 54卷3期 (1996/09) Pp. 1-9

https://doi.org/10.6623/chem.1996041

摘要

理論計算顯示，具四個未成對價電子相當於此四個價電子分別懸置在其T_d結構四個頂點的C_(28)(基態為^5A_2開殼式(Open-Shell)組態)，在其T_d結構的四個頂點接上H形成穩定之C_(28)H_4球簇分子。鑑於同屬T_d 結構的金剛烷(分子式：C_(10)H_(16))於六○年至九四年陸續合成在其T_d四個頂點接上鹵素，形成穩定之1,3,5,7 -四鹵化金剛烷結晶(1,3,5,7-tetrahaloadamantane)。本研究即針對此同屬於T_d對稱群之C_(28)H_4分子，將頂點上之四個H同時以鹵素取代，系列探肘C_(28)H_4，此等四鹵化-C_(28)分子之幾何結構，及其游離能、能隙、分子解離能、生成熟和振動頻率等。由此等分子優選後之振動頻率計算結果，成們發現此鹵化系列C_(28)X_4(X =H, F, CI, Br 及I)球簇分子皆為位能面上之穩定極小點，類似1,3,5,7-四鹵化金剛烷，推測當可能為日後化學家所合成之物質。

關鍵字

C28X (X = H, F, CI, Br及I) ； 1,3,5,7-四鹵化金剛烷

並列摘要

Theoretical calculation showed that the C_(28) cluster with T_d symmetries has four unpaired electrons in an ^5A_2 open-shell ground state and that the dangling bonds located at each of the four tetrahedral vertices easily reactive with H atoms to form C_(28)H_4 molecular cluster. In T_d symmetry, adamantane (C_(10)H_(16)) was synthesized in 1941 by Prelog, V. etc ., and it's known derivatives 1,3,5,7-tetrahaloadamantane were synthesized from 1960 up-to-the 1994. In present work, we substituted halogen for hydrogen in C_(28)H_4 its four tetrahedral vertices and studied its' geometrical structure, first ionization potentials, energy gaps(~£HOMo-LUMO)' binding energies, heat offormations and vibrational frequencies. We found that the derivatives C_(28)H_4 (X =H, F, CI, Br and I) are all the minima in the potential energy surfaces similar to the 1,3,5,7-tetrahaloadamantane compounds and will be synthesized by chemist in the future.

並列關鍵字

C_(28) ； C_(28)X_4 (X = H, F, CI, Br and I) ； 1,3,5,7-tetrahaloadamantane