Molecular structure of 2,2,4,4,6,6-hexamethyl-1,3,5-trimethylenecyclohexane as determined by gas-phase electron diffraction.
The molecular structure of 2,2,4,4,6,6-hexamethyl-1,3,5-trimethylenecyclohexane has been determined in the gas phase at a nozzle tip temperature of 340 K. The electron diffraction data were found to be consistent with a model where the cyclohexane ring adopts a distorted twist-boat conformation. The averaged geometrical parameters (r(g) and 90 degree angle (alpha)) obtained from least squares analysis are r(C=C) = 1.346(4) A, r(C-C)(ring) = 1.537(1) A, r(C-C)(Me) = 1.543(1) A, 90 degree angle C(6)C(1)C(2) = 117.5(11) degrees, 90 degree angle C(1)C(2)C(3) = 113.1(12) degrees, and 90 degree angle MeCMe = 108.2(13) degrees. The experimental results are consistent with the results from HF/6-311G(d) and MP2/6-311G(d) calculations where the distorted twist-boat form is found to be lower in energy than the chair form by 9.85 and 10.7 kcal/mol, respectively.
Shen
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Department of Chemistry, Colgate University, 13 Oak Drive, Hamilton, NY 13346, USA. mshen@mail.colgate.edu
Traetteberg
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