Cl3C-CF3		PDF
		Chlorine
	Nuclear Quadrupole Coupling Constants
	in 1,1,1-Chloro-2,2,2-fluoroethane
	Calculation of the chlorine nqcc's in 1,1,1-chloro-2,2,2-fluoroethane was made on a molecular structure derived ab initio (see below).  These are given in Table 1.  Structure parameters and atomic coordinates are given in Tables 2 and 3, respectively.
	Coordinate Systems
	Xuu is the component of the nqcc tensor along the threefold symmetry axis.  Corresponding to the atomic coordinates given below in Table 3, Xvv and Xww are the components along the v- and w- axes for the Cl atom in the uv-plane.
	Subscripts x,y,z refer to the principal axes of the nqcc tensor.  The y-axis is chosen coincident with the w-axis.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
	Table 1.  Chlorine nqcc's in Cl3C-CF3 (MHz).     Calc. Expt.   35Cl Xuu 27.51 Xvv - 69.53   Xww 42.02 Xuv 37.95   Xxx 40.59 Xyy 42.02 Xzz - 82.61 ETA 0.017 Øz,u 70.98 Øu,CCl 71.40 Øz,CCl   0.41
	The pyramid formed by the z-principal axes of the three Cl nqcc tensors is somewhat 'sharper' than the molecular pyramid.  This is atypical of the pyramidal trichlorides.
	Molecular Structure
	The molecular structure was optimized at the MP2/6-311+G(d,p) level of theory assuming Cs symmetry.  The optimized CC single bond length was then corrected using the equation obtained from linear regression analysis of the data given in Table IX of Ref.[6].  Likewise, the optimized CF bond lengths were corrected by regression analysis of the data given in Table VI of Ref.[5].  For the CCl bond, the structure was optimized at the MP2/6-311+G(2d,p) level and corrected by linear regression analysis of the data given in Table 4 of Ref.[4].  The CH bond lengths were corrected using r = 1.001 ropt, where ropt is obtained by MP2/6-31G(d,p) optimization [7].  Interatomic angles used in the calculation are those given by B3P86/6-311+G(3d,3p) optimization.
	Table 2. Molecular structure parameters (Å and degrees). CCl 1.7546 CC 1.5408 CF 1.3254 CCF 110.42 CCCl 108.60
	Table 3. Atomic coordinates. (More figures are shown than are significant.)     u (Å)   v (Å)   w (Å)   Cl - 0.946239 1.662919 0.0 Cl - 0.946239 - 0.831460 ± 1.440130 C - 0.386488 0.0 0.0 C 1.154312 0.0 0.0 F 1.616713 - 1.242123 0.0 F 1.616713 0.621062 ± 1.075710
	[1] I.Merke, L.Poteau, G.Wlodarczak, A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996).
	[2] R.M.Villamañan, W.D.Chen, G.Wlodarczak, J.Demaison, A.G.Lesarri, J.C.López, and J.L.Alonso, J.Mol.Spectrosc. 171,223(1995).
	[3] J.Demaison, J.Cosléou, R.Bocquet, and A.G.Lesarri, J.Mol. Spectrosc. 167,400(1994).
	[4] J.Demaison and G.Wlodarczak, Structural Chem. 5,57(1994).
	CFCl3		SiHCl3		CH3CCl3		OPCl3
	NCl3		PCl3		AsCl3		SPCl3
	CH3Cl		CH2Cl2		CHCl3
	Table of Contents
	Molecules/Chlorine
						CF3CCl3.html
						Last Modified 5 Aug 2003