BrH2C-CH2OH
		Bromine
	Nuclear Quadrupole Coupling Constants
	in 2-Bromoethanol
	Calculation of the bromine nqcc's in 2-bromoethanol was made on structures derived ab initio by the methods of the Lille group, as described below.   These are compared with the experimental nqcc's of Azrak and Wilson [1] in Tables 1 and 2.  Eigenvectors of the nqcc tensor are given in Table 3.  Structure parameters are given in Table 4.  Atomic coordinates and rotational constants are given in Tables 5 and 6, respectively.
	In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor; 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 diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation of the B1LYP/TZV(3df,3p) model for calculation of the bromine nqcc's.
	Table 1.  79Br nqcc's in 2-Bromoethanol (MHz).  Calculation was made on ab initio structures with C-O-H geometry and all interatomic angles given by (1) MP2/6-311+G(d,p), and (2) MP2/6-311+G(2d,p) optimization.  See below.     Calc. (1) Calc. (2) Expt. [1]     Xaa 245.83 244.37 240(5) Xbb   11.08   11.98   15(5) Xcc - 256.91 - 256.35 - 255(5) Xab * 366.51 367.28 - 370(20) Xac * - 107.67 - 106.36 ~ 1/3 Xab Xbc * - 88.51 - 88.52 < |Xac|   RMS 4.2 (2.5 %) 3.2 (1.9 %) RSD 1.58 (0.39 %) 1.58 (0.39 %)   Xxx - 254.09 - 254.32 Xyy - 283.58 - 283.11 Xzz 537.67 537.43 ETA 0.054 0.054 Øz,CBr 0.55 0.53
	* Here and in Table 2, the algebraic signs of the off-diagonal components depend on the orientation of the molecule with respect to the positive/negative sense of the a,b,c axes.  Here, the algebraic signs correspond to the atomic a,b,c coordinates given in Table 4.  In this regard, calculated and experimental off-diagonal nqcc's can be brought into agreement by transformation: b --> -b.
	Table 2.  81Br nqcc's in 2-Bromoethanol (MHz).  Calculation was made on ab initio structures with C-O-H geometry and all interatomic angles given by (1) MP2/6-311+G(d,p), and (2) MP2/6-311+G(2d,p) optimization.  See below.     Calc. (1) Calc. (2) Expt.     Xaa 206.08 204.86 190(10) Xbb     8.62     9.36   17(10) Xcc - 214.70 - 214.23 - 207(10) Xab * 306.02 306.66 - 305(20) Xac * - 89.91 - 88.81 ~ 1/3 Xab Xbc * - 73.76 - 73.77 < |Xac|   RMS 11.4 (8.2 %) 10.5 (7.6 %) RSD 1.38 (0.40 %) 1.38 (0.40 %)
	Table 3.  2-Bromoethanol - 79Br.  Eigenvectors (direction cosines) of the nqcc tensor.  Ab initio structure with C-O-H geometry and all interatomic angles given by MP2/6-311+G(2d,p) optimization.        x    y    z   a - 0.6062 - 0.0508 0.7937 b 0.7353 0.3444 0.5837 c - 0.3030 0.9374 - 0.1714
	Molecular Structure
	The ropt structures were derived as follows: The molecular structure was optimized at the MP2/6-311+G(d,p) level of theory.  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. [2].  CH bond lengths were corrected using r = 1.001 × ropt, where ropt is obtained by MP2/6-31G(d,p) optimization [3].
	For the C-Br bond length, optimization was made at the MP2/6-311+G(2d,p) level of theory of the C-Br 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 1.9558 Å which, after correction is 1.9453 Å.
	C-O-H geometry and all interatomic angles are those given by (1) MP2/6-311+G(d,p) optimization and (2) MP2/6-311+G(2d,p) optimization.
	Table 4.  Heavy atom and C-O-H structure parameters (Å and degrees).  Complete structures are given here in Z-matrix format.   (1) MP2/6-311+G(d,p) (2) MP2/6-311+G(2d,p)   ropt (1) ropt (2) CBr 1.9453 1.9453 CC 1.5102 1.5102 CO 1.4141 1.4169 OH(5) 0.9634 0.9674 BrCC 110.74 110.68 CCO 112.74 112.88 COH 106.66 107.38 Br - - - H(5) 2.7396 2.7634
	Table 5.   2-Bromoethanol - 79Br.  Atomic coordinates, ropt.  MP2/6-311+G(2d,p) COH and angles.     a (Å)   b (Å)   c (Å) Br - 0.9218 - 0.1045 0.0208 C 0.6275 1.0284 - 0.2958 C 1.8547 0.4518 0.3692 O 2.2431 - 0.7960 - 0.1785 H 1.5113 - 1.4132 - 0.0391 H 1.6971 0.3835 1.4501 H 2.6900 1.1316 0.1875 H 0.7510 1.0808 - 1.3743 H 0.3800 2.0083 0.1063
	Table 6.  2-Bromoethanol - 79Br.  Rotational constants (MHz).  (1) MP2/6-311+G(d,p)  and (2) MP2/6-311+G(2d,p) COH and angles.    ropt (1)  ropt (2)       Expt. [1] A 12 047.5 11 995.8 11 876.226 ± 0.1 B   2 360.5   2 360.9   2 363.755 ± 0.1 C   2 093.3   2 091.9   2 089.978 ± 0.1
	[1] R.G.Azrak and E.B.Wilson, J.Chem.Phys. 52,5299(1970)
	[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).
	2-Chloroethanol			Methyl Bromide
	Ethyl Bromide			1-Bromo-1-Fluoroethane
	Table of Contents
	Molecules/Bromine
						BrH2CCH2OH.html
						Last Modified 8 March 2006