C3N2H3I
	Iodine and Nitrogen
	Nuclear Quadrupole Coupling Constants
		in 2-Iodoimidazole
	Iodine and nitrogen nuclear quadrupole coiupling constants in 2-iodoimidazole were determined by Cooper et al. [1].
	Calculation of the 127I and 14N nqcc's was made here on a molecular structures given by B3LYP/cc-pVTZ (cc-pVTZ-PP for I) optimization.  Calculated nqcc's are compared with the experimental values in Tables 1 - 3.  Structure parameters are given in Table 4, rotational constants in Table 5.
	In Tables 1 - 3, 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 the angle between its subscripted parameters.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation of the B1LYP/TZV(df,p) model for calculation of iodine efg's/nqcc's; and in Tables 2 and 3, of the B3PW91/6-311+G(df,pd) model for nitrogen.
	Table 1.  Iodine nqcc's in 2-Iodoimidazole (MHz).  Calculation was made on B3LYP/cc-pVTZ optimized molecular structure.      Calc    Expt [1]     127I Xaa - 2031.1 - 2026.5535(80) Xbb - cc     46.0     34.3916(84) * Xbb 1038.5 1030.4726(58) ** Xcc   992.5   996.0809(58) ** |Xab|     93.0     93.55(15) RMS   5.7 (0.42 %) RSD 15.2 (1.23 %)   Xxx 1041.3 1033.333(11) Xyy   992.5   996.0809(58) Xzz - 2033.9 - 2029.413(12) ETA - 0.0240 Øz,a 1.73 Øa,CI 1.81 Øz,CI 0.08
	* This is given in Ref [1] as 4.3916(84), which does not reproduce the quadrupole axis system values also given in Ref [1], 34.3916(84) does.
	** Calculated here from experimental Xaa and Xbb - cc
	Table 2.  Nitrogen (pyrrolic) nqcc's in 2-Iodoimidazole (MHz).  Calculation was made on B3LYP/cc-pVTZ optimized molecular structure.     Calc Expt [1]     14N(1) Xaa 1.336 1.3270(73) Xbb - cc 4.231 4.1848(60) Xbb 1.448 1.4289(47) Xcc - 2.784 - 2.7559(47) |Xab| 0.111 0.39(26) RMS 0.020 (1.1 %) RSD 0.030 (1.3 %)   Xxx 1.268 0.98(26) Xyy 1.516 1.77(26) Xzz - 2.784 - 2.7561(47) ETA 0.0892 Øz,c   0   0
	* Calculated here from experimental Xaa and Xbb - cc
	Table 3.  Nitrogen (pyridinic) nqcc's in 2-Iodoimidazole (MHz).  Calculation was made on B3LYP/cc-pVTZ optimized molecular structure.     Calc Expt [1]     14N(3) Xaa 1.585 1.5506(73) Xbb - cc - 5.688 - 5.5700(60) Xbb - 3.637 - 3.5603(47) * Xcc 2.051 2.0097(47) * |Xab| 1.642 1.89(24) RMS 0.054 (2.3 %) RSD 0.030 (1.3 %)   Xxx 2.059 2.17(14) Xyy 2.051 2.0097(47) Xzz - 4.110 - 4.18(14) ETA - 0.00183 Øz,a 73.91 Øa,bi** 71.58 Øz,bi   2.33
	* Calculated here from experimental Xaa and Xbb - cc
	** "bi" is bisector of CNC angle.
	Table 4.  2-Iodoimidazole: B3LYP/cc-pVTZ optimized structure parameters (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  I,2,R8,1,A7,5,D6,0  R1=1.36210834  R2=1.30166124  R3=1.37793038  R4=1.36574553  R5=1.00478419  R6=1.07623225  R7=1.07484595  R8=2.09167151  A1=112.29714668  A2=105.15848295  A3=110.59659878  A4=126.14450536  A5=121.17487458  A6=132.59784098  A7=121.72754155  D1=0.  D2=0.  D3=180.  D4=180.  D5=180.  D6=180.
	Table 5.  2-Iodoimidazole: Rotational Constants (MHz), ropt = B3LYP/cc-pVTZ    ropt     Expt [1] A 9453. 9357.00567(56) B 1003. 1017.73058(21) C   907.   917.75860(22)
	[1]  G.A.Cooper, C.J.Anderson, C.Medcraft, N.Walker, J.Mol.Spectros. 354,15(2018).
	G.A.Cooper, C.J.Anderson, C.Medcraft, A.Legon, N.Walker, Abstract FB11, 72nd ISMS, Champaign-Urbana, Illinois, 2017.
	4-Iodopyrazole		Iodobenzene		3-Iodothiophene		Imidazole
	4-Iodoimidazole
	Table of Contents
	Molecules/Iodine
	Molecules/Nitrogen
						2Iimidazole.html
						Last Modified 16 Sept 2018