Crystal and molecular structures of dimesitylketene and bis(3,5‐dibromo‐2,4,6‐trimethylphenyl)ketene. Intrinsic torsional angles and buttressing effects in 1,1‐dimesitylvinyl propellers

Silvio E. Biali*, Michael Gozin, Zvi Rappoport

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The crystal and molecular structures of dimesitylketene (1) and bis(3,5‐dibromo‐2,4,6‐trimethylphenyl)ketene (2), the first free ketenes to be studied by X‐ray diffraction, have been determined. The molecules of 1 and 2 have crystallographic C1 and C2 symmetry, respectively, and exist in a propeller conformation. Molecular mechanics calculations of 1 and 2 using a modification of Allinger's new allene parameters reproduce satisfactorily the structural parameters of the ketenes. The torsional angles of the aryl rings in 1 and 2 are similar (ca. 50°) and are regarded as ‘intrinsic’ values for a 1,1‐dimesitylvinyl propeller. From the similarity in aryl torsional angles in 1 and 2 it is concluded that the buttressing effects in 2 (if any) are not markedly manifested in the structural parameters of 2.

Original languageEnglish
Pages (from-to)271-280
Number of pages10
JournalJournal of Physical Organic Chemistry
Volume2
Issue number3
DOIs
StatePublished - Apr 1989
Externally publishedYes

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