O=C=C(H)Br
	Bromine
	Nuclear Quadrupole Coupling Constants
		in Bromoketene
	Calculation of the Br nqcc tensors in bromoketene was made here on a molecular structure derived by MP2/aug-cc-pVTZ(G03) optimization (ropt), and on this same optimized structure but with empirical correction of the  CBr, C=C, and C=O bond lengths (~re, see here).  These nqcc's are compared with the experimental values [1] in Table 1.  Structure parameters are given in Table 2, rotational constants in Table 3.
	In Table 1, 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.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the plane of the molecule.  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 (percent of average experimental nqcc's).  RSD is the residual standard deviation of calibration of the B1LYP/TZV(3df,3p) model for calculation of the bromine nqcc's.
	Table 1. Bromine nqcc's in O=C=C(H)Br (MHz).  Calculation was made on the ropt and approximate re structures.     Calc / ropt Calc / ~re Expt. [1]     79Br Xaa 431.78 436.73 427.4(18) Xbb - 89.79 - 92.36 - 86.4 Xcc - 341.98 - 344.38 - 341.0(9) |Xab| 410.23 410.83 413.12(82)   RMS 3.25 (1.14 %) 6.68 (2.34 %) RSD 1.58 (0.39 %) 1.58 (0.39 %)   Xxx - 315.11 - 316.44 - 316.0(13) Xyy - 341.98 - 344.38 - 341.0(9) Xzz 657.09 660.82 656.9(13) ETA 0.0409 0.0423 Øz,a 28.78 28.61 29.06(6) Øa,BrC 30.50 30.29 Øz,BrC   1.72   1.68   81Br Xaa 361.28 365.41 358.90(85) Xbb - 75.56 - 77.69 - 73.50 Xcc - 285.72 - 287.72 - 285.40 |Xab| 342.39 342.89 345.11(44)   RMS 1.83 (0.76 %) 4.67 (1.95 %) RSD 1.38 (0.40 %) 1.38 (0.40 %)
	Table 2.  Bromoketene molecular structure parameters ropt and approximate re (Å and degrees).     ropt   ~re CH 1.0747 1.0747 CBr 1.8728 1.8814 HCBr 119.89 119.89 HCC 121.45 121.45 C=C 1.3185 1.3150 C=O 1.1684 1.1588 C=C=O 179.58 179.58
	[1] N.P.C.Westwood, W.Lewis-Bevan, and M.C.L.Gerry, J.Mol.Spectrosc. 136,93(1989).
	Ketene		Chloroketene		Cyanoketene
	Table of Contents
	Molecules/Bromine
						BrHCCO.html
						Last Modified 9 Dec 2011