Density functional theory (DFT) B3LYP calculations characterize the structure and stability of the clusters of tropylium ion (Tr+) coordinated by methanol molecules Tr+(MeOH)n with n = 1-7. Methanol molecules are bound together through strong O-H···O type hydrogen bonds, resulting in a cyclic structure when n ≥ 3, and the methanol cluster thus formed coordinates to Tr+ through weak C-H···O type hydrogen bonds. Thus, the formation of the Tr+(MeOH)n clusters is mediated by two kinds of hydrogen bonds. Calculated distances of the O -H···O hydrogen bonds lie in the range 1.570-1.991 Å (1.712 Å in average) while those of the C-H···O hydrogen bonds lie in the range 2.083-2.319 Å (2.160 Å in average). Mass spectroscopic experiments demonstrated that Tr+(MeOH)4 is a dominant, magic-numbered species and that Tr+(MeOH)3 and Tr+(MeOH)5 are minor [Chemical Communication, (2001) in press]. The experimental result is analyzed from the viewpoint of energetics. The specific size effect on the stability of Tr+(MeOH)n is a direct consequence of the stability of the (MeOH)n fragment itself.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physical and Theoretical Chemistry