F2C=CCl2						PDF
		Chlorine
	Nuclear Quadrupole Coupling Constants
	in 1,1-Dichloro-2,2-difluoroethylene
	Calculation of the chlorine nqcc's in 1,1-dichloro-2,2-difluoroethylene was made on a structure derived ab initio, as described below.  These nqcc's are given in Table 1.  Structure parameters are given in Table 2.
	In Table 1, 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. Chlorine nqcc's in F2C=CCl2 (MHz).  Calculation was made on the ab initio ropt structure.     Calc. Expt.     35Cl Xaa   9.01 Xbb - 47.36 Xcc 38.35 |Xab| 53.19   RSD 0.49 (1.1 %)   Xxx 41.02 Xyy 38.35 Xzz - 79.37 ETA - 0.034 Øz,a 58.96 Øa,CCl 59.27 Øz,CCl   0.31     37Cl Xaa   7.10 Xbb - 37.33 Xcc 30.23 |Xab| 41.92   RSD 0.44 (1.1 %)
	The angle between the two z-axes is 0.62o smaller than the ClCCl angle. This is atypical of the XCl2 dichloride moiety.
	Ab Initio Molecular Structure
	The molecular structure was optimized at the MP2/6-311+G(d,p) level of theory assuming Cs symmetry.  The optimized C=C bond length was then corrected using the equation obtained from linear regression analysis of the data given in Table IX of Ref. [3].  Likewise, the optimized CF bond lengths were corrected by regression analysis of the data given in Table VI of Ref. [2].  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. [1].  Interatomic angles are those given by MP2/6-311+G(2d,p) optimization.
	Table 2.  Molecular structure parameters, ropt (Å and degrees).   CCl 1.7027 CF 1.3087 C=C 1.3289 CCCl 120.73 CCF 124.02
	[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).
	H2C=CHCl		c-FHC=CHCl		H2C=CCl2		ClHC=CCl2
	H2C=CFCl		t-FHC=CHCl		F2C=CFCl		c-ClHC=CHCl
	Table of Contents
	Molecules/Chlorine
						CF2CCl2.html
						Last Modified 14 Feb 2006