STRUCTURE AND CONFORMATION OF TRIS(2,2,2-TRIFLUOROETHYL)AMINE, N(CH2CF3)(3), IN THE GASEOUS AND SOLID-STATE

The conformational properties and geometric structure of tris(2,2,2-tr ifluoroethyl)amine, N(CH2CF3)(3), have been determined for the gaseous and solid state by electron diffraction and X-ray crystallography, re spectively. In the gas phase the predominant conformer possesses C-1 s ymmetry, and small contributions of C-s (<25%) and/or C-3 (<10%) confo rmers cannot be excluded. In the crystal, however, the molecule adopts a structure with C-3 symmetry. Raman spectra at temperatures between +24 and -35 degrees C demonstrate the presence of a mixture of at leas t two conformers in the liquid phase. The following geometric paramete rs (r(a) distances and angle(alpha) angles with 3 sigma uncertainties) were derived for the nitrogen-carbon skeleton in the gas phase: N-C = 1.436(6) Angstrom, C-C = 1.527(5) Angstrom, CNC = 116.6(9)degrees, (N CC)(mean) = 113.7(9)degrees, Phi(1) = 180 degrees (ass), Phi(2) = 10.8 (11)degrees, and Phi(3) = 19.4(11)degrees. Phi(i) are the lp-N-C-C dih edral angles (lp = nitrogen lone pair). The corresponding parameters f or the crystal structure (mean values with sigma uncertainties) are ve ry similar: N-C = 1.453(3) Angstrom, C-C = 1.507(3) Angstrom, CNC = 11 5.1(2)degrees, NCC = 111.6(2)degrees, and Phi(i) = 22.1(3)degrees. Acc ording to ab initio calculations CHF/3-21G with polarization functions at nitrogen), the most stable structure possesses C-1 symmetry and th e C-s and C-3 conformers are higher in energy by 0.7 and 3.6 kcal/mol, respectively.