CH2BrCH2CN
	Bromine and Nitrogen
	Nuclear Quadrupole Coupling Constants
	in trans 3-Bromopropionitrile
	Calculation of the bromine and nitrogen nqcc tensors in the trans (Cs) conformer of 3-bromopropionitrile was made on a structure derived ab initio as discussed below.   These are compared with the experimental bromine nqcc's [1] in Tables 1 and 2.  Calculated nitrogen nqcc's are given in Tables 3 and 4.  No experimental nqcc's for nitrogen have been reported.  Structure parameters are given in Table 5, rotational constants in Table 6.
	In Tables 1 - 4, subscripts a,b,c refer to the principal axes of the inertia tensor, subscripts x,y,z to the principal axes of the nqcc tensor.  Ø (degrees) is the angle between its subscripted parameters. ETA = (Xxx - Xyy)/Xzz.
	RMS is the root mean square difference between calculated and experimental nqcc's (percentage of the average experimental nqcc).  RSD is the residual standard deviation of calibration of the model for calculation of the nqcc's.
	Table 1.  79Br nqcc's in trans CH2BrCH2CN (MHz).     Calc. Expt. [1]     79Br Xaa 487.11 413(6) Xbb - 197.64 - 194 * Xcc - 289.47 - 219 * |Xab| 283.86   RMS 59 (21 %) RSD 1.58 (0.39 %)   Xxx - 281.49 Xyy - 289.47 Xzz 570.96 ETA 0.0140 Øz,a 18.28 Øa,CBr 17.90 Øz,CBr   0.38
	* Calculated here from the experimental Xaa and  (Xbb - Xcc)/Xaa  = 0.061(110) [1].
	Table 2.  81Br nqcc's in trans CH2BrCH2CN (MHz).     Calc. Expt. [1]     81Br Xaa 407.00 349(6) Xbb - 165.16 - 183 * Xcc - 241.84 - 166 * |Xab| 212.05   RMS 56 (24 %) RSD 1.38 (0.40 %)   Xxx - 238.18 Xyy - 241.84 Xzz 477.02 ETA 0.0140 Øz,a 18.27
	* Calculated here from the experimental Xaa and  (Xbb - Xcc)/Xaa  = - 0.048(67) [1].
	Table 3.  14N nqcc's in trans CH279BrCH2CN (MHz).     Calc. Expt.     14N Xaa - 3.577 Xbb 1.554 Xcc 2.023 |Xab| 2.059   RSD 0.030 (1.3 %)   Xxx 2.278 Xyy 2.023 Xzz - 4.301 ETA - 0.059 Øz,a 19.37 Øa,CN 19.75 Øz,CN   0.38
	Table 4.  14N nqcc's in trans CH281BrCH2CN (MHz).     Calc. Expt.     14N Xaa - 3.577 Xbb 1.554 Xcc 2.023 |Xab| 2.059   RSD 0.030 (1.3 %)
	Molecular Structure
	The molecular structure was optimized at the MP2/6-311+G(d,p) level of theory.  The optimized C-C, C-C(N), and CN bond lengths were corrected using equations obtained from linear regression analyses of the data given in Tables VIII and IX 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 [3].  Interatomic angles used in the calculation are those given by MP2/6-311+G(2d,p) optimization.
	For the C-Br bond length, optimization was made at the MP2/6-311+G(2d,p) level of theory of the C-Br equilibrium bond lengths in CH3Br, CH2Br2, HCCBr, and BrCN.  Linear regression of the calculated versus equilibrium bond lengths yields the following relationship, by which the C-Br was corrected:
			r = 0.9946 × ropt + 0.0001,   RSD = 0.0015 Å.
	The optimized C-Br bond length is 1.9442 Å which, after correction is 1.934 Å.
	Table 5.  trans 3-Bromopropionitrile.  Heavy atom structure parameters (Å and degrees).  The complete structure is given here in Z-Matrix format.   NC(8) 1.156 C(8)C(3) 1.462 C(3)C(2) 1.521 C(2)Br 1.934 NC(8)C(3) 178.43 C(8)C(3)C(2) 109.98 C(3)C(2)Br 110.26
	Table 6.  trans 3-Bromopropionitrile.  Rotational constants (MHz).  Normal species.   Calc. ropt    Expt. [1] A 26 950.2 26 251.22(77.73) B   1 037.8   1 033.69(1) C   1 011.9   1 007.76(1)
	[1] S.Xu and M.D.Harmony, J.Mol.Struct. 274,115(1992).
	[2] J.Demaison, J.Cosléou, R.Bocquet, and A.G.Lesarri, J.Mol.Spectrosc. 167,400(1994).
	[3] J.Demaison and G.Wlodarczak, Structural Chem. 5,57(1994).
	t-3-Chloropropionitrile			gau-3-Chloropropionitrile
	Methyl Bromide			Ethyl Bromide
	2-Bromopropane			2-Bromoethanol
	Table of Contents
	Molecules/Bromine
	Molecules/Nitrogen
						tCH2BrCH2CN.html
						Last Modified 9 July 2006