H2PCN
	Nitrogen
	Nuclear Quadrupole Coupling Constants
		in Cyanophosphine
	Kang and Novick [1] determined for cyanophosphine an ro structure, derived an ab initio structure, and measured the nitrogen nqcc's.  Calculation of the nqcc's was made here on these structures.  The calculated nqcc's are compared with the experimental values in Tables 1 and 2.  Structure parameters, effective and ab initio, are shown in Table 3.
	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 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 H2PCN (MHz).  Calculation was made on the ro structure of Kang and Novick [1].     Calc. Expt. [1]     14N Xaa - 4.620 - 4.589(2) Xbb 2.770 2.677(6) Xcc 1.850 1.912(6) |Xab| 0.134   RMS 0.067 (2.2 %) RSD 0.030 (1.3 %)   Xxx 1.853 Xyy 2.770 Xzz - 4.622 ETA 0.198 Øz,a 1.18 Øa,CN 2.16 Øz,CN 0.98
	Table 2.  Nitrogen nqcc's in H2PCN (MHz).  Calculation was made on the ab initio structure of Kang and Novick [1].     Calc. Expt. [1]     14N Xaa - 4.632 - 4.589(2) Xbb 2.767 2.677(6) Xcc 1.865 1.912(6) |Xab| 0.148   RMS 0.064 (2.1 %) RSD 0.030 (1.3 %)   Xxx 1.869 Xyy 2.767 Xzz - 4.635 ETA 0.194 Øz,a 1.30 Øa,CN 2.64 Øz,CN 1.34
	Table 2. Molecular structure parameters [1] (Å and degrees).    ro ab initio CN 1.1577 1.1561 CP 1.787 1.7878 PH 1.424 1.4176 PCN 174.6 173.92 HPC   95.7   95.16 HPH   93.9   94.21 HPCN ± 132.75 ± 132.64
	[1] L.Kang and S.E.Novick, J.Mol.Spectrosc. 225,66(2004).
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						Last Modified 16 March 2004