Stereochemical analysis of 1,1,2,2-tetraarylethanes. 1. Static stereochemistry

Paolo Finocchiaro, Devens Gust, John Devens Gust, John P. Hummel, Pietro Maravigna, Kurt Mislow

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Empirical force field calculations on 1,1,2,2-tetraphenylethane (TPE) and 1,1,2,2-tetrakis(2,6-xylyl)ethane (TXE) show that these molecules adopt a C2 ground-state conformation in which the methine hydrogens are in anti positions. The dihedral angles of all four rings are equally signed; these systems can therefore be viewed as four-bladed molecular propellers. Comparison of the geometric parameters for TPE and TXE reveals that TXE is a highly strained molecule, as demonstrated by the unusual elongation of the central C-C bond and the unusual enlargement of the central C-C-C angles. The 1H NMR spectra of tetramesitylethane (TME) and 1,2-dimesityl-1,2-bis(2,4,6-trimethoxyphenyl)ethane (2) at the slow exchange limit are also consistent with a C2 conformation in solution. The racemic and meso forms of 2 have been separated and configurations have been assigned to the two stereoisomers on the basis of their NMR spectra. Treatment of the static stereochemistry of 1,1,2,2-tetraarylethanes in terms of a group theoretical approach leads to a description of the full permutation-inversion group, to the calculation of the number of isomers for any given substitution pattern in such systems, and to the recognition of systems which are stereochemically correspondent to 1,1,2,2-tetraarylethanes.

Original languageEnglish
Pages (from-to)4945-4952
Number of pages8
JournalJournal of the American Chemical Society
Volume98
Issue number16
Publication statusPublished - 1976

    Fingerprint

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Finocchiaro, P., Gust, D., Gust, J. D., Hummel, J. P., Maravigna, P., & Mislow, K. (1976). Stereochemical analysis of 1,1,2,2-tetraarylethanes. 1. Static stereochemistry. Journal of the American Chemical Society, 98(16), 4945-4952.