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)H3, 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 (3σ). Normal-coordinate analysis based on B3LYP/6-311+G∗∗ calculations supports the existence of the four conformers. The dihedral angle ϕ1(C4C2N1C3) (= −ϕ2(C5C3N1C2)) of the tt conformer was 170(4)° whereas the ϕ1 and ϕ2 values of the other conformers were fixed at the B3LYP/6-311++G(2df,p) values: 72.4° and −163.3° for the g+t, −66.0° and −158.2° for the g−t, and 60.3° and 63.5° for the g+g+. Average values of the structural parameters (rg/Å and ∠α/°) with 3σ are: 〈r(N–C)〉 = 1.462(2), 〈r(C–C)〉 = 1.523(3), 〈r(C–H)〉 = 1.113(2), 〈∠CNC〉 = 111.6(5), 〈∠NCC〉 = 114.5(5), 〈∠NCH/∠CCHMe〉 = 110.6(5).