Density functional theory study of adamantanediyl dications C10H142+ and protio-adamantyl dications C10H162+

doi:10.1073/pnas.0404137101

Density functional theory study of adamantanediyl dications C₁₀H₁₄²⁺ and protio-adamantyl dications C₁₀H₁₆²⁺

Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA 90089-1661

Contributed by George A. Olah, June 14, 2004

Abstract

Structures of the isomeric adamantanediyl dications C₁₀H₁₄ ²⁺ and protio-1- and protio-2-adamantyl dications C₁₀H₁₆ ²⁺ were investigated by using the density functional theory (DFT) method at the B3LYP/6–31G** level. Four structures, 1 b–e, were found to be minima on the potential energy surface of C₁₀H₁₄ ²⁺. The 1,3-adamantanediyl dication 1b with two bridgehead tertiary carbocationic centers was found to be the most stable structure. On the potential energy surface of C₁₀H₁₆ ²⁺ (protonated adamantly cation), five structures, 2 b–f, were found to be minima. Each of the structure contains a two-electron, three-center bond. The C—C protonated 1-adamantyl dication, 2f, was characterized as the most stable structure. ¹³C NMR chemical shifts of the structures were also calculated by using gauge-including atomic orbital-density functional theory and gauge-including atomic orbital-self-consistent field methods.

Footnotes

↵ † To whom correspondence should be addressed. E-mail: olah{at}usc.edu.
Abbreviations: DFT, density functional theory; ZPE, zero point vibrational energies; GIAO, gauge-including atomic orbital; SCF, self-consistent field; 2e—3c, two-electron, three-center.
↵ ‡ This is paper no. 64 in the series “Chemistry in Superacids.” Paper no. 63 is ref. 16.