




















C_{2}H_{2}N_{2}S 













































Nitrogen 



Nuclear
Quadrupole Coupling Constants 



in 1,3,4Thiadiazole 

































Calculation
of the
nitrogen nqcc's in 1,3,4Thiadiazole was
made on the substitution molecular structure of Stiefvater [1]. These
are
compared with the experimental nqcc's [2] in Table 1.
Structure
parameters are given in Table 2. 












In Table 1, subscripts a,b,c refer to the
principal axes of the inertia tensor; x,y,z to the principal axes
of the nqcc tensor. The nqcc yaxis is chosen coincident with the
inertia caxis, these are perpendicular to the molecular plane.
Ø (degrees) is the angle between its subscripted
parameters. ETA = (X_{xx}  X_{yy})/X_{zz}. 


RMS is the root mean square
difference between calculated and experimental nqcc's (percent of the
average magnitude of the experimental nqcc's). RSD is the
calibration residual standard deviation of the B3PW91/6311+G(df,pd)
model for calculation of nitrogen efg's/nqcc's. 































Table 1. Nitrogen nqcc's in 1,3,4Thiadiazole (MHz). Calculation was made
on the r_{s} structure of Stiefvater [1]. 













Calc. 

Expt. [2] 










^{14}N 
X_{aa} 
 
3.618 
 
3.72(2) 



X_{bb} 

1.596 

1.61(5) 



X_{cc} 

2.022 

2.11(5) 



X_{ab} 
± 
2.737 













RMS 

0.07_{8} (3.1 %) 





RSD 

0.030 (1.3 %) 













X_{xx} 

2.769 





X_{yy} 

2.022 





X_{zz} 
 
4.791 





ETA 
 
0.156 





Ø_{z,a} 

23.19 





Ø_{a,bi} 

33.92 





Ø_{z,bi} * 

10.72 
























* The zaxis makes an angle of 10.72^{o} with the external bisector ('bi') of the CNN angle and tilts toward the adjacent N. 















Table 2. 1,3,4Thiadiazole. Molecular structure parameters, r_{s }[1] (Å
and degrees). 




SC 
1.7200(3) 

CN 
1.3031(5) 

NN 
1.3711(5) 

CH 
1.0771(4) 

CSC 
86.38(2) 

SCN 
114.64(3) 

CNN 
112.17(1) 

SCH 
122.49(2) 























[1] O.L.Stiefvater,
Z.Naturforsch. 44a,29(1989). 


[2] See ... L.Nygaard,
E.Asmussen, F.H.Høg, R.C.Maheshwari, C.H.Nielsen,
I.B.Petersen,
J.RastrupAndersen, and G.O.Sørensen, J.Mol.Struct.
8,225(1971). 












B.Bak, L.Nygaard, E.J.Pedersen, and J.RastrupAndersen, J.Mol.Spectrosc. 19,283(1966); r_{s} structure. 






















Thiazole 
1,3,4Oxadiazole 
1,2,5Oxadiazole 

1,2,3Thiadiazole 
1,2,4Thiadiazole 
1,2,5Thiadiazole 





















Table of Contents 





Molecules/Nitrogen 






























134TDZ.html 






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Modified 23 June 2004 









