15min:

RAM S BHATTA, AMY GAO AND DAVID S PERRY, Department of Chemistry, The University of Akron, OH 44325-3601.

Two-dimensional torsion-inversion surfaces for methylamine, protonated methanol and ethyl radical were calculated and fit to a function containing a polynomial in the inversion angle( ) and trigonometric functions of the torsional angle( ). Calculations were done at the B3LYP, MP2, and CCSD(T) levels with the 6-311++G(d,p) and 6-311++G(3df, 2p) basis sets and partial optimization. CH₃NH₂, CH₃OH₂⁺ and CH₃CH₂ have G₁₂ symmetry with 6-equivalent minima which are located by the various calculations at inversion angles 6.5 to 11; 42 to 45.5 and 52.5 to 55 degrees respectively on either side of planar. The three molecules have very different barriers to inversion ranging from no barrier for CH₃CH₂ to 838 cm^-1 for CH₃OH₂⁺ to 1837 cm^-1 for CH₃NH₂. The dominant torsion-inversion coupling term in all cases has the form cos3 .