CH3CH2Cl
		Chlorine
	Nuclear Quadrupole Coupling Constants
		in Ethyl Chloride
	Calculation of the chlorine nqcc's in ethyl chloride 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 in Table 1.  Structure parameters are compared with the substitution parameters in Table 2.
	Table 1.  35Cl nqcc's in CH3CH2Cl (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 - 49.60 - 50.22 - 49.29(9) Xbb 13.77 14.38 13.65 Xcc 35.83 35.85 35.64 |Xab| 42.87 42.11   RMS 0.22 (0.68 %) 0.69 (2.1 %) RSD 0.49 (1.1 %) 0.49 (1.1 %)   Xxx 35.39 35.15 35.36 * Xyy 35.83 35.85 35.64 Xzz - 71.22 - 71.00 - 71.00 ETA 0.006 0.010 0.004 Øz,a 26.76 26.26 26.86 Øa,CCl 25.80 25.65 25.80 Øz,CCl   0.96   0.61   1.06
	* Calculated here from the experimental diagonal nqcc's and |Xab| = 42.87 MHz.  Calc. (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.[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 [4].  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 2.  Molecular structure parameters (Å and degrees).     rs [1] MP2 <'s B3P86 <'s C(1)Cl 1.789 1.7864 C(1)C(2) 1.520 1.509 C(1)H 1.089 1.088 C(2)Hs 1.092 1.091 C(2)Ha 1.092 1.088 CCCl 111.02 111.01 111.62 HC(1)Cl 106.54 107.01 106.03 C(2)C(1)H 111.61 111.35 111.98 HC(1)H 109.26 108.91 108.84 C(1)C(2)Hs 109.27 109.59 109.42 C(1)C(2)Ha 110.44 110.78 111.08 HsC(2)Ha 109.23 108.61 108.36 HaC(2)Ha 108.21 108.40 108.46
	[1] M.Hayashi and T.Inagusa, J.Mol.Struct. 220,103(1990).
	[2] I.Merke, L.Poteau, G.Wlodarczak, A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996).
	[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).
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