CFCl3
		Chlorine
	Nuclear Quadrupole Coupling Constants
		in Trichlorofluoromethane
	35Cl nqcc's in trichlorofluoromethane were first measured in 1967 by Wolf et al. [1], and revisited in 1987 by Carpenter et al. [2].  Loubser, 1961 [3] and Long et al., 1960 [4] determined effective structures.
	Coupling constants calculated here are compared with the experimental nqcc's [2] in Tables 1 and 2.  It will be seen that good agreement with the experimental nqcc's is obtained on a structure that is an average of the structures of Loubser and Long et al.  Structure parameters and atomic coordinates (of this average effective structure) are given in Tables 3 and 4, 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 4, Xvv and Xww are the components along the v- and w- axes for the Cl atom in the uv-plane.  ETAQ = (Xvv - Xww)/Xuu.
	The subscripts x,y,z refer to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the w-axis.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
	RMS is the root mean square difference between calculated and experimental diagonal nqcc's.  RSD is the residual standard deviation of calibration of the model for calculation of the nqcc's.
	Table 1.  35Cl nqcc's in CFCl3 (MHz). Calc. [3] ro structure of Loubser. Calc. [4] ro structure of Long et al.     Calc [3] Calc [4] Expt. [2]     Xuu 29.87 27.54 28.98(4) ETAQ - 3.77 - 4.00 - 3.85(20)
	As mentioned above, it is evident that a structure somewhere between that of Loubser and that of Long et al. would give calculated parameters in better agreement with the experimental values.  Calculation was made, therefore, on a structure that is a simple average of these two. This result is shown in Table 2.
	Table 2.  Chlorine nqcc's in CFCl3 (MHz).     Calc. Expt. [2]   35Cl Xuu 28.76 28.98(4) ETAQ - 3.89 - 3.85(20) Xvv - 70.16 - 70.28 *   Xww 41.40 41.30 * Xuv 34.58   RMS 0.15 (0.33 %) RSD 0.49 (1.1 %)   Xxx 39.63 Xyy 41.38 Xzz - 81.01 - 83(6) ETA 0.022 0 (Assumed) Øz,u 72.52 Øu,CCl 71.42 Øz,CCl   1.10
	* Calculated here from the experimental Xuu and ETAQ.
	The pyramid formed by the z-principal axes of the three Cl nqcc tensors is somewhat 'flatter' than the molecular pyramid.  This is typical of the pyramidal trichlorides.
	Table 3. Molecular structure parameters (Å and degrees). ro [3] ro [4] avg. ro CF 1.362 1.33 1.346 CCl 1.754 1.76 1.757 ClCCl 111 109.7 110.35
	Table 4. Atomic coordinates, average ro structure. (More figures are shown than are significant.)     u (Å)   v (Å)   w (Å) Cl - 0.310763 1.665449 0.0 Cl - 0.310763 - 0.832725 ± 1.442321 C 0.248994 0.0 0.0 F 1.594994 0.0 0.0
	[1] A.A.Wolf, Q.Williams, and T.L.Weatherly, J.Chem.Phys. 47,5101(1967).
	[2] J.H.Carpenter, P.J.Seo, and D.H.Whiffen, J.Mol.Spectrosc. 123,187(1987).
	[3] J.H.N.Loubser, J.Chem.Phys. 36,2808(1961).
	[4] M.W.Long, Q.Williams, and T.L.Weatherly, J.Chem.Phys. 33,508(1960).
	CF3Cl		CF2Cl2		CH3CCl3		OPCl3
	NCl3		PCl3		AsCl3		SPCl3
	CH3Cl		CH2Cl2		SiHCl3
	Table of Contents
	Molecules/Chlorine
						CFCl3.html
						Last Modified 3 June 2003