STRUCTURAL INVESTIGATION OF TERT-BUTYLETHYLAMINE BY GAS ELECTRON-DIFFRACTION, ABINITIO CALCULATIONS AND VIBRATIONAL SPECTROSCOPY

The molecular structure and conformation of t-butylethylamine (N-ethyl-2-methyl-2-propanamine), [GRAPHICS] were investigated by gas electron diffraction. The geometrical constraints used in the data analysis were taken from the results of ab initio calculations at the 4-21G level. Vibrational spectra were measured and harmonic force constants were evaluated to calculate mean amplitudes and shrinkage corrections. Diffraction data are explained in terms of only one conformer with C3C2NC6 (phi-1) and C2NC6C7 (phi-2) dihedral angles of -179.3-degrees and 178.8-degrees, respectively (these angles are defined as zero when the fragments take the eclipsed form), but a small amount (less than 7%) of a second conformer with phi-1 = 161.3-degrees and phi-2 = 78.9-degrees cannot be ruled out. The values of the principal bond lengths and angles (r(g) and angle-alpha) of the predominant conformer with estimated uncertainties (3-sigma) are: r(N-C2) = 1.476(1) angstrom, r(N-C6) = 1.465(1) angstrom, r(C2-C3) = 1.537(1) angstrom, r(C2-C4) = 1.543(1) angstrom, r(C2-C5) = 1.536(1) angstrom, r(C6-C7) = 1.533(1) angstrom, < r(C-H) > = 1.116(2) angstrom, angle CNC = 117.6(11)-degrees, angle NC2C3 = 105.6(5)-degrees, angle NC2C4 = 112.5(5)-degrees, angle NC2C5 = 108.9(5)-degrees, angle NC6C7 = 112.6(16)-degrees, angle C3C2C4 = 108.8(12)-degrees, angle C3C2C5 = 108.4(12)-degrees angle C4C2C5 = 112.2-degrees and < angle CCH > = 110.5(7)-degrees. Uncertainties related to the geometrical constraints were not included and the true error limits must be larger than 3-sigma.