Molecular structure and conformation of diethylmethylamine determined by gas electron diffraction and vibrational spectroscopy combined with theoretical calculations

We have investigated the molecular structure and conformation of diethylmethylamine,C(4)H3C(2)H2N(1)[CH3]C(3)H2C(5)H-3, by gas electron diffraction and vibrational spectroscopy with the aid of theoretical calculations. Diffraction data are consistent with a conformational mixture of 35(14)% tt + 27(14)% g(+)t + 20(17)% g(-)t + 18(23)% g(+)g(+) where the numbers in parentheses denote three times the standard errors (3 sigma). Normal-coordinate analysis based on B3LYP/6-311+G** calculations supports the existence of the four conformers. The dihedral angle phi(1)(C4C2N1C3) (= -phi(2)(C50N1C2)) of the tt conformer was 170(4)degrees whereas the phi(1) and phi(2) values of the other conformers were fixed at the B3LYP/6-311++G(2df,p) values: 72.4 degrees and -163.3 degrees for the g(+)t, -66.0 degrees and -158.2 degrees for the g(-)t, and 60.3 degrees and 63.5 degrees for the g(+) 9(+). Average values of the structural parameters (r(g)/angstrom and angle(alpha)/degrees) with 3 sigma are: < r(N-C)> = 1.462(2), < rC-C)> = 1.523(3), < r(C-H)> = 1.113(2), <angle CNC > = 111.6(5), <angle NCC > = 114.5(5), <angle ZNCH/angle CCHMe > = 110.6(5). (C) 2006 Elsevier B.V. All rights reserved.