Computational studies on stable triplet states of heteroacetylenes and the effects of halogen substituents

Mu Jeng Cheng, Hsin Mei Cheng, San Yan Chu

Research output: Contribution to journalArticlepeer-review

Abstract

This paper describes theoretical studies of halogen-substituted heteroacetylenes (XC=MY, M = Si and Ge; X, Y = H, Cl and F) performed at the QCISD(T)/6-311G**//QCISD/6-31G* level of theory. The electronegative halogen substituents destabilize the singlet state such that the triplet state tends to become favorable. The triplet state has the bifunctional electronic structure of a triplet carbene joined to a heavy singlet carbene. We found that the substituents effectively reduce the energy of the donor-acceptor interactions (ED-A) between the two in-plane lone pairs of electrons of the singlet state; therefore, the remaining π bond is less favorable energetically than the triplet state with a σ bond. A related phenomenon occurs for the homonuclear heavy acetylenes in singlets in which the lead compound RPbPbR switches to a Pb-Pb σ bond from the π bonds observed for the lighter acetylenes.

Original languageEnglish
Pages (from-to)10495-10500
Number of pages6
JournalJournal of Physical Chemistry A
Volume110
Issue number35
DOIs
Publication statusPublished - 2006 Sep 7

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

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