C4H6N2
		Nitrogen
	Nuclear Quadrupole Coupling Constants
	in 2-Methylimidazole
		N-Methylimidazole		4-Methylimidazole		5-Methylimidazole
	14N nuclear quadrupole coupling constants in 2-methylimidazole were determined by Gougoula, et al. [1].
	Calculation of the 14N nuclear quadrupole coupling constants was made here on a B3LYP/cc-pVTZ  opimized molecular structure, and on a heavy atom rs structure [1] with hydrogen parameters determined by B3LYP/cc-pVTZ partial optimization.
	Calculated and experimental nqcc's are compared in Tables 1 and 2.  Structure parameters in Z-matrix format are given in Table 3, rotational constants are compared in Table 4.
	In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  ETA = (Xxx - Xyy)/Xzz.  Ø (degrees) is angle between its subscripted parameters.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's.  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen efg's/nqcc's.
	Table 1.  Pyrrolic 14N(1) nqcc's in 2-Methylimidazole (MHz).  Calculation was made on  the ropt = B3LYP/cc-pVTZ optimized structure, and on the heavy atom rs structure.     Calc /ropt Calc /rs Expt [1]     Xaa 1.266 1.276 1.3010(59) Xbb - Xcc 4.236 4.082 4.178(10) Xbb 1.485 1.403 1.4385 * Xcc - 2.751 - 2.679 - 2.7395 * Xab 0.132 0.258 RMS 0.025 (1.4 %) 0.043 (2.4 %) RSD 0.030 (1.3 %) 0.030 (1.3 %)   Xxx 1.204 1.074 Xyy 1.547 1.605 Xzz - 2.751 - 2.679 ETA 0.125 0.198 Øz,c  zero  zero
	* Calculated here from experimental Xaa and Xbb - Xcc
	Table 2.  Pyridinic 14N(3) nqcc's in 4-Methylimidazole (MHz).  Calculation was made on the ropt = B3LYP/cc-pVTZ optimized structure, and on the heavy atom rs structure.     Calc /ropt Calc /rs Expt [1]     Xaa 1.374 1.455 1.3742(64) Xbb - Xcc - 5.463 - 4.591 - 5.399(10) Xbb - 3.418 - 3.023 - 3.3866 * Xcc 2.044 1.568 2.0124 * Xab 1.703 1.691 RMS 0.026 (1.3 %) 0.157 (7.7 %) RSD 0.030 (1.3 %) 0.030 (1.3 %)   Xxx 1.918 1.816 Xyy 2.044 2.198 Xzz - 3.962 - 4.014 ETA 0.0319 0.0949 Øz,bi**
	* Calculated here from experimental Xaa and Xbb - Xcc
	** "bi" is bisector of C(2)N(3)C(4) angle.
	Table 3.  2-Methylimidazole:  Structure parameters,  ropt = B3LYP/cc-pVTZ optimized structure, and rs = heavy atom substitution structure. (Å and degrees).   N  C,1,R1  N,2,R2,1,A1  C,3,R3,2,A2,1,D1,0  C,4,R4,3,A3,2,D2,0  H,1,R5,2,A4,3,D3,0  H,4,R6,3,A5,2,D4,0  H,5,R7,4,A6,3,D5,0  C,2,R8,1,A7,5,D6,0  H,9,R9,2,A8,1,D7,0  H,9,R10,2,A9,1,D8,0  H,9,R11,2,A10,1,D9,0       ropt       rs  R1=1.36701504  R2=1.31323427  R3=1.37619667  R4=1.36408958  R5=1.00473456  R6=1.07662148  R7=1.07492373  R8=1.48981417  R9=1.09268076  R10=1.09268076  R11=1.0869601  A1=110.58203512  A2=106.12814348  A3=110.48263401  A4=126.25917014  A5=121.51382593  A6=132.62271265  A7=123.35198793  A8=111.84651164  A9=111.84651164  A10=108.60086061  D1=0.  D2=0.  D3=180.  D4=180.  D5=180.  D6=180.  D7=-60.46748093  D8=60.46748093  D9=180. B1=1.31646544 B2=1.33588122 B3=1.41347775 B4=1.36612763 B5=1.00491656 B6=1.07607884 B7=1.07469401 B8=1.49522152 B9=1.09269311 B10=1.09269311 B11=1.08576411 A1=113.32423712 A2=103.44814456 A3=110.31025569 A4=126.40113322 A5=121.35108400 A6=133.04463201 A7=125.03987730 A8=111.91981406 A9=111.91981406 A10=108.10450448 D1=0. D2=0. D3=180. D4=180. D5=180. D6=180. D7=-60.44727520 D8=60.44727520 D9=180.
	Table 4.  2-Methylimidazole: Rotational Constants (MHz).    Calc /ropt  Calc /rs     Expt [1]    A     8979.   8910. 8892.9063(26)  B     3605.   3614. 3601.19596(95)  C     2614.   2613. 2604.8287(98)
	[1] E.Gougoula, C.Medcraft, J.Heitkämper, and N.Walker, Abstract MI01, 74th ISMS, Champaign-Urbana, Illinois, 2019;  J.Chem.Phys. 151,144301(2019).
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