CH2F2
		Deuterium
	Nuclear Quadrupole Coupling Constants
		in Difluoromethane
	Deuterium nqcc's along carbon-hydrogen bond direction in deuterated difluoromethane have been reported by Nelson et al. [1].  An equilibrium structure has been reported by Hirota [2].
	Calculation of the deuterium nqcc's was made here on the equilibrium structure.  These results are shown in Table 1.  The structure parameters are given in Table 2.  Sensitivity of the principal values of the nqcc tensor to CH bond length and HCH angle, within the uncertainties in the equilibrium structure, was investigated.  This result is shown in Table 3.
	In Table 1, the subscripts a,b,c refer to the principal axes of the inertia tensor, the subscripts x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia a-axis, these are perpendicular to the HCH plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
	Table 1.  Deuterium nqcc's in CD2F2 (kHz).     Calc. Expt. [1]     2H Xaa - 86.6 Xbb   - 8.8 Xcc   95.4 Xbc ± 126.3   Xxx - 93.4(20) Xyy - 86.6(19) Xzz 179.9(36) * 186(10)  ** ETA - 0.038 - 0.15(5) Øz,b 33.79 Øb,CD 33.6 Øz,CD   0.2
	* See below for estimates of the uncertainties in the principal values of the nqcc tensor.
	** Bond axis nqcc.
	Table 2.  Molecular structure parameters, re [2] (Å and degrees). CF 1.3508 CH 1.084(3) HCH 112.8(3) FCF 108.49
	Table 3. Sensitivity of the principal values of the nqcc tensor (kHz) to CH = 1.084±0.003 Å and HCH = 112.8±0.3o, which are the uncertainties in the re structure.    CH HCH   Xxx   Xyy   Xzz   1.084 112.5 - 93.4 - 86.5 180.0 1.084 112.8 - 93.4 - 86.6 179.9 1.084 113.1 - 93.3 - 86.6 179.9   1.081 112.8 - 95.1 - 88.2 183.3 1.084 112.8 - 93.4 - 86.6 179.9 1.087 112.8 - 91.7 - 85.0 176.6
	Estimate of the uncertainty in Xzz is
		Xzz = Xzz ± [(3.4)2 + (1.1)2]1/2 = 179.9(36) kHz
	where ±3.4 kHz is due to the uncertainty in the CH bond length (Table 3) and ±1.1 kHz is the calibration residual standard deviation of the B3LYP/6-31G(df,3p) model for calculation of the nqcc's.  The nqcc's are not sensitive to the uncertainty in the HCH angle.
	[1] A.C.Nelson, S.G.Kukolich, and D.J.Ruben, J.Mol.Spectrosc. 51,107(1974).
	[2] E.Hirota, J.Mol. Spectrosc. 71,145(1978).
	CDH3		CDF3		CD3F		CD2Cl2
	CDCl3		CD3Cl		CD2Br2		CD3Br
	CD3CN		CD2(CN)2		HCCCD3		CDnX4-n
	Table of Contents
	Molecules/Deuterium
	Summary/Methyls  Deuterium nqcc's in the substituted methanes.
						CH2F2.html
						Last Modified 30 May 2003