ClF2C-CH3						PDF
		Chlorine
	Nuclear Quadrupole Coupling Constants
	in 1-Chloro-1,1-Difluoroethane
	Calculation of the chlorine nqcc's in 1-chloro-1,1-difluoroethane were made on structures with bond lengths derived ab initio by the methods of the Lille group, as described below.  Interatomic angles used are those given by (1) MP2/6-311+G(d,p), and (2) B3P86/6-311+G(3d,3p) optimization.  Calculated nqcc's are compared with the experimental nqcc's [1] in Tables 1 and 2.  Structure parameters are given in Z-Matrix format in Table 3.
	In Tables 1 and 2, RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation for the B1LYP/TZV(3df,2p) model for calculation of the chlorine nqcc's.
	Subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular symmetry plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
	Table 1.  35Cl nqcc's in ClF2C-CH3 (MHz).  Calculation was made on the ab initio structure with interatomic angles given by (1) MP2/6-311+G(d,p), and (2) B3P86/6-311+G(3d,3p) optimization.     Calc. (1) Calc. (2) Expt. [1]     Xaa - 72.30 - 72.14 - 72.0861(57) Xbb 36.81 36.68 36.719(13) Xcc 35.50 35.46 35.368(13) |Xab|   0.47   0.65   RMS 0.16 (0.3 %) 0.07 (0.1 %) RSD 0.49 (1.1 %) 0.49 (1.1 %)   Xxx 36.81 36.68 36.72 * Xyy 35.50 35.46 35.368 Xzz - 72.31 - 72.14 - 72.09 ETA - 0.018 - 0.017 - 0.019 Øz,a 0.25 0.34 0.34 Øa,CCl 0.01 0.14 0.14 Øz,CCl 0.24 0.48 0.48
	* Calculated here from the experimental diagonal nqcc's and |Xab| = 0.65 MHz.  Calc. (2).
	Table 2.  37Cl nqcc's in ClF2C-CH3 (MHz).  Calculation was made on the ab initio structure with interatomic angles given by (1) MP2/6-311+G(d,p), and (2) B3P86/6-311+G(3d,3p) optimization.     Calc. (1) Calc. (2) Expt. [1]     Xaa - 56.98 - 56.85 - 56.8162(73) Xbb 29.01 28.90 28.911(19) Xcc 27.98 27.95 27.905(19) |Xab|   0.53   0.69   RMS 0.12 (0.3 %) 0.03 (0.1 %) RSD 0.44 (1.1 %) 0.44 (1.1 %)
	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.[4].  Likewise, the optimized CF bond lengths were corrected by regression analysis of the data given in Table VI of Ref.[3].  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.[2].  The CH bond lengths were corrected using r = 1.001 ropt, where ropt is obtained by MP2/6-31G(d,p) optimization [5]. Interatomic angles used in the calculation are those given by (1) MP2/6-311+G(d,p) and (2) B3P86/6-311+G(3d,3p) optimization.
	Table 3. Structure parameters (Å and degrees).   Cl C 1 R1 C 2 R2 1 A1 H 3 R3 2 A3 1   D3 H 3 R3 2 A3 1 - D3 H 3 R4 2 A4 1 180. F 2 R5 3 A5 6   D5 F 2 R5 3 A5 6 - D5   MP2 Angles B3P86 Angles R1 1.7686 R2 1.496 R3 1.086 R4 1.088 R5 1.346 A1 112.40 112.60 A3 109.55 109.77 A4 108.30 108.28 A5 110.64 111.02 D3   60.17   60.30 D5   58.94   59.22
	[1] J.L.Alonso, J.C.López, S.Blanco, and A.Guarnieri, J.Mol.Spectrosc. 182,148(1997).
	[2] I.Merke, L.Poteau, G.Wlodarczak, A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996).
	[3] 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)
	[4] J.Demaison, J.Cosléou, R.Bocquet, and A.G.Lesarri, J.Mol.Spectrosc. 167,400(1994).
	[5] J.Demaison and G.Wlodarczak, Structural Chem. 5,57(1994).
	CH3Cl		CH3CH2Cl		CH2ClCHF2		CH3CCl3
	CF2ClCH2F		CH2ClCH2F		CF2ClCHF2		CF2ClCF3
	CF3Cl		CH2ClCF3
	Table of Contents
	Molecules/Chlorine
						CF2ClCH3.html
						Last Modified 14 Aug 2003