Thiazole						PDF
	Nitrogen and Sulfur
	Nuclear Quadrupole Coupling Constants
		in Thiazole
	Calculation of nitrogen and sulfur nqcc's in thiazole was made on the substitution structure of Nygaard et al. [1], and on a molecular structure obtained by B3PW91/6-31G(2d,2pd) optimization [2].  These are compared in Tables 1 - 8 with the experimental nqcc's of Kretschmer and Dreizler [3].  Structure parameters are compared in Table 9.
	In Tables 1 and 8, 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 standard deviation of calibration of the model for calculation of the nqcc's.
	Table 1. Nitrogen nqcc's in Thiazole (MHz).  Calculation was made on the rs structure of Nygaard et al. [1].     Calc. Expt. [3]     14N Xaa - 2.706 - 2.7481(15) Xbb 0.056 0.08505 Xcc 2.650 2.6630 |Xab| 2.581   RMS 0.030 (1.7 %) RSD 0.030 (1.3 %)   Xxx 1.602 1.613 * Xyy 2.650 2.6630 Xzz - 4.252 - 4.276 ETA 0.246 0.246 Øz,a 30.92 30.62 Øa,bi 31.53 31.53 Øz,bi**   0.61   0.91
	* Calculated here from the experimental diagonal nqcc's and the calculated off-diagonal nqcc.
	** Angle between the z-axis and the bisector ( 'bi' ) of the CNC angle.
	Table 2. Nitrogen nqcc's in Thiazole (MHz).  Calculation was made on the B3PW91/6-31G(2d,2pd) structure.     Calc. Expt. [3]     14N Xaa - 2.745 - 2.7481(15) Xbb 0.078 0.08505 Xcc 2.666 2.6630 |Xab| 2.558   RMS 0.005 (0.26 %) RSD 0.030 (1.3 %)   Xxx 1.589 1.592 * Xyy 2.666 2.6630 Xzz - 4.255 - 4.256 ETA 0.253 0.252 Øz,a 30.55 30.51 Øa,bi 31.36 31.36 Øz,bi**   0.81   0.85
	* Calculated here from the experimental diagonal nqcc's and the calculated off-diagonal nqcc.
	** Angle between the z-axis and the bisector ( 'bi' ) of the CNC angle.
	Table 3. Nitrogen nqcc's in Thiazole-33S (MHz).  Calculation was made on the rs structure of Nygaard et al. [1].     Calc. Expt. [3]     14N Xaa - 2.699 - 2.7411(49) Xbb 0.049 0.0767(69) Xcc 2.650 2.6644 |Xab| 2.585   RMS 0.030 (1.6 %) RSD 0.030 (1.3 %)
	Table 4. Nitrogen nqcc's in Thiazole-33S (MHz).  Calculation was made on the B3PW91/6-31G(2d,2pd) structure.     Calc. Expt. [3]     14N Xaa - 2.738 - 2.7411(49) Xbb 0.071 0.0767(69) Xcc 2.666 2.6644 |Xab| 2.562   RMS 0.004 (0.22 %) RSD 0.030 (1.3 %)
	Table 5. Nitrogen nqcc's in Thiazole-34S (MHz).  Calculation was made on the rs structure of Nygaard et al. [1].     Calc. Expt. [3]     14N Xaa - 2.693 - 2.7359(23) Xbb 0.043 0.0716 Xcc 2.650 2.6664 |Xab| 2.588   RMS 0.031 (1.7 %) RSD 0.030 (1.3 %)
	Table 6. Nitrogen nqcc's in Thiazole-34S (MHz).  Calculation was made on the B3PW91/6-31G(2d,2pd) structure.     Calc. Expt. [3]     14N Xaa - 2.731 - 2.7359(23) Xbb 0.065 0.0716 Xcc 2.666 2.6664 |Xab| 2.566   RMS 0.005 (0.27 %) RSD 0.030 (1.3 %)
	Table 7.  33S nqcc's in Thiazole (MHz).  Calculation was made on the rs structure of Nygaard et al. [1]. Calc. [a] B3LYP/6-311G(3df,3p) Model. Calc. [b] B3LYP/TZV+(3df,3p) Model.     Calc. [a] Calc. [b] Expt. [3]     Xaa   7.54   7.62   7.1708(61) Xbb - 25.85 - 25.95 - 26.1749(69) Xcc 18.30 18.32 19.0041(130) |Xab|   0.81   0.88   RMS 0.49 (2.8 %) 0.49 (2.8 %) RSD 0.39 (1.7 %) 0.35 (1.5 %)   Xxx   7.56   7.65   7.19 * Xyy 18.30 18.32 19.0041 Xzz - 25.86 - 25.97 - 26.20 ETA 0.415 0.411 0.451 Øx,a 1.38 1.49 1.46 Øa,bi 3.28 3.28 3.28 Øx,bi** 1.90 1.79 1.82
	* Calculated here from the experimental diagonal nqcc's and 0.85 MHz for |Xab|.
	** Angle between the x-axis and the bisector ( 'bi' ) of the CSC angle.
	Table 8.  33S nqcc's in Thiazole (MHz).  Calculation was made on the B3PW91/6-31G(2d,2pd) structure. Calc. [a] B3LYP/6-311G(3df,3p) Model. Calc. [b] B3LYP/TZV+(3df,3p) Model.     Calc. [a] Calc. [b] Expt. [3]     Xaa   7.17   7.25   7.1708(61) Xbb - 25.96 - 26.06 - 26.1749(69) Xcc 18.79 18.81 19.0041(130) |Xab|   0.73   0.80   RMS 0.17 (0.98 %) 0.14 (0.78 %) RSD 0.39 (1.7 %) 0.35 (1.5 %)   Xxx   7.19   7.27   7.19 * Xyy 18.79 18.81 19.0041 Xzz - 25.98 - 26.08 - 26.19 ETA 0.447 0.442 0.451 Øx,a 1.27 1.38 1.32 Øa,bi 3.35 3.35 3.35 Øx,bi** 2.08 1.97 2.03
	* Calculated here from the experimental diagonal nqcc's and 0.77 MHz for |Xab|.
	** Angle between the x-axis and the bisector ( 'bi' ) of the CSC angle.
	Table 9. Molecular structure parameters, B3PW91/6-31G(2d,2pd) ropt and rs [1] (Å and degrees).     rs [1]   ropt  S(1)C(2) 1.7239(9) 1.7313 C(2)N(3) 1.3042(11) 1.2988 N(3)C(4) 1.3721(2) 1.3690 C(4)C(5) 1.3670(4) 1.3635 C(5)S(1) 1.7130(3) 1.7187 C(2)H(2) 1.0767(18) 1.0818 C(4)H(4) 1.0798(1) 1.0818 C(5)H(5) 1.0765(2) 1.0781 C(5)S(1)C(2)   89.33(3)   89.03 S(1)C(2)N(3) 115.18(1) 115.14 C(2)N(3)C(4) 110.12(2) 110.28 N(3)C(4)C(5) 115.81(2) 116.09 C(4)C(5)S(1) 109.57(1) 109.46 S(1)C(2)H(2) 121.26(5) 120.56 N(3)C(4)H(4) 119.35(1) 119.18 C(4)C(5)H(5) 129.03(3) 129.10
	[1] L.Nygaard, E.Asmussen, J.H.Høg, R.C.Maheshwari, C.H.Nielsen, I.B.Petersen, J.Rastrup-Andersen, and G.O.Sørensen, J.Mol.Struct. 8, 225(1971).
	[2] W.C.Bailey, J.Mol.Spectrosc. 209,57(2001).
	[3] U.Kretschmer and H.Dreizler, Z.Naturforsch. 48a,1219(1993).
	J.Wiese and D.H.Sutter, Z.Naturforsch. 35a,712(1980): Xaa = -2.708(22), Xbb = 0.113(34), Xcc = 2.595(34) MHz.
	2-Methylthiazole			1,2,4-Thiadiazole			Pyrazole
	4-Methylthiazole			1,2,5-Thiadiazole			Oxazole
	5-Methylthiazole			1,3,4-Thiadiazole			Imidazole
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	Molecules/Nitrogen
	Molecules/Sulfur
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						Last Modified 27 Sept 2004