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