C4H4S
		Sulfur
	Nuclear Quadrupole Coupling Constants
	in Thiophene
	Calculation of the 33S nqcc's in thiophene was made on the substitution structure of Bak et al. [1], on the equilibrium structure of Kochikov et al. [2], and on a structure obtained here by B3PW91/6-31G(2d,2pd) optimization.  These calculated nqcc's are compared with the experimental results of Kretschmer et al. [3] in Tables 1-3. Structure parameters are compared in Table 4.
	In Tables 1 - 3, 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 model for calculation of the nqcc's.
	Subscripts a,b,c refer to the principal axis of the inertia tensor.  The a-axis is coincident with the bisector of the CSC angle, the c-axis is perpendicular to the plane of the molecule.
	Table 1.  33S nqcc's in Thiophene (MHz).  Calculation was made on the rs structure of Bak et al. [1].     Calc [a] B3LYP/6-311G(3df,3p)   Calc [b] B3LYP/TZV+(3df,3p)   Calc. [a] Calc. [b]  Expt. [3]     Xaa   7.21   7.31   6.8610(64) Xbb - 27.49 - 27.59 - 27.8135(63) Xcc 20.28 20.27 20.9525(47)   RMS 0.47 (2.5 %) 0.49 (2.6 %) RSD 0.39 (1.7 %) 0.35 (1.5 %)
	Table 2.  33S nqcc's in Thiophene (MHz).  Calculation was made on the re structure of Kochikov et al. [2].     Calc [a] B3LYP/6-311G(3df,3p)   Calc [b] B3LYP/TZV+(3df,3p)   Calc. [a] Calc. [b]  Expt. [3]     Xaa   7.72   7.83   6.8610(64) Xbb - 27.18 - 27.27 - 27.8135(63) Xcc 19.45 19.44 20.9525(47)   RMS 1.06 (5.7 %) 1.08 (5.8 %) RSD 0.39 (1.7 %) 0.35 (1.5 %)
	Table 3.  33S nqcc's in Thiophene (MHz).  Calculation was made on the B3PW91/6-31G(2d,2pd) ropt structure.     Calc [a] B3LYP/6-311G(3df,3p)   Calc [b] B3LYP/TZV+(3df,3p)   Calc. [a] Calc. [b]  Expt. [3]     Xaa   6.86   6.96   6.8610(64) Xbb - 27.77 - 27.87 - 27.8135(63) Xcc 20.92 20.91 20.9525(47)   RMS 0.03 (0.16 %) 0.07 (0.37 %) RSD 0.39 (1.7 %) 0.35 (1.5 %)
	Table 4.  Thiophene.  Molecular structure parameters. (Å and degrees).    rs [2] re [3]   ropt S(1)C(2) 1.7140 1.704 1.7197 C(2)C(3) 1.3696 1.372 1.3660 C(3)C(4) 1.4232 1.421 1.4229 C(2)H(2) 1.0776 1.085 1.0787 C(3)H(3) 1.0805 1.088 1.0816 C(5)S(1)C(2)   92.16   92.4   91.95 S(1)C(2)C(3) 111.47 111.6 111.42 C(2)C(3)C(4) 112.45 112.2 112.60 S(1)C(2)H(2) 119.84 119.9 119.93 C(4)C(3)H(3) 124.27 124.4 124.04   The major differences between the substitution and optimized structures - namely S(1)C(2) and C(2)C(3) - can be attributed to the small substitution a-coordinate of C(2).
	[1] B.Bak, D.Christensen, L.Hansen-Nygaard, and J.Rastrup-Andersen, J.Mol. Spectrosc. 7,58(1961).
	[2] I.V.Kochikov, Yu.I.Tarasov, V.P.Spiridonov, G.M.Kuramshina, D.W.H.Rankin, A.S.Saakjan, and A.G.Yagola, J.Mol.Struct. 567-568,29(2001).
	[3] U.Kretschmer, W.Stahl, and H.Dreizler, Z.Naturforsch. 48a,733 (1993).
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	Molecules/Sulfur
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						Last Modified 1 Oct 2004