H2PCCCN
	Nitrogen
	Nuclear Quadrupole Coupling Constants
		in Cyanophosphaacetylene
	Calculation of the nitrogen nqcc tensor in cyanophosphaacetylene was made on a structure given by MP2/aug-cc-pVTZ(G03) optimization with corrected ~re bond lengths for C-C, C=C, and C=N, and on a partial ro structure derived by Kang et al. [1], which authors also determined the nitrogen nqcc's.  Calculated and experimental nqcc's are compared in Tables 1 and 2.  Structure parameters are shown in Table 3, rotational constants in Table 4.
	In Tables 1 and 2, 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 b-axis, which is 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 nqcc's (percentage of average experimental nqcc).  RSD is the residual stand deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the nqcc's.
	Table 1.  Nitrogen nqcc's in H2PCCCN (MHz).  Calculation was made on the partial ~re structure derived here.     Calc. Expt. [1]     14N Xaa - 4.290 - 4.247(1) Xbb 2.363 2.44 * Xcc 1.927 1.80 * |Xac| 0.105   RMS 0.089 (3.1 %) RSD 0.030 (1.3 %)   Xxx 1.929 Xyy 2.363 Xzz - 4.291 ETA 0.101 Øz,a 0.97 Øa,CN 0.97 Øz,CN 0.006
	* Derived here from experimental Xaa and Xbb - Xcc = 0.64(5) MHz [1].
	Table 2.  Nitrogen nqcc's in H2PCCCN (MHz).  Calculation was made on the partial ro structure, wherein the H2P geometry is that of the MP2/aug-cc-pVTZ(G03) optimization.     Calc. Expt. [1]     14N Xaa - 4.296 - 4.247(1) Xbb 2.374 2.44 * Xcc 1.922 1.80 * |Xac| 0.171   RMS 0.084 (3.0 %) RSD 0.030 (1.3 %)   Xxx 1.927 Xyy 2.374 Xzz - 4.301 ETA 0.104 Øz,a 1.57 Øa,CN 1.52 Øz,CN 0.058
	Table 3.  Cyanophosphaacetylene.  Molecular structure parameters, partial ~re and partial ro (Å and degrees).     ~re     ro NC(6) 1.1617 1.161 C(6)C(1) 1.3729 1.370 C(1)C(2) 1.2141 1.218 C(2)P 1.7752 1.770 PH 1.4127 NC(6)C(1) 179.99 180. C(6)C(1)C(2) 178.67 180. C(1)C(2)P 172.89 173.6 C(2)PH 95.95 HPH 94.38 HPC(2)C(1) ± 132.47
	Table 4.  Cyanophosphaacetylene.  Rotational Constants (MHz).   Partial ~re Partial ro Expt [1] A 129606.0 128987.4 128236.5 B     1320.8     1323.9     1323.04891(7) C     1319.3     1322.5     1321.51672(6)
	[1] L.Kang, A.J.Minei, and S.E.Novick, J.Mol.Spectrosc. 240,255(2006).
	F2PCN		F2NCN		H2PCN
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	Molecules/Nitrogen
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						Last Modified 5 March 2009