C4H5N3O
	Nitrogen
	Nuclear Quadrupole Coupling Constants
		in Cytosine
	Nitrogen nqcc's in each of the following conformers of cytosine were determined by Alonso et al. [1].
		trans					cis
	Note: At the B3LYP/cc-pVTZ level of theory, Etrans < Ecis by 3.1 kJ/mole.
	Calculation of the nitrogen nqcc tensors in each conformer was made here on molecular roptstructures given by B3P86/6-31G(3d,3p) and B3LYP/cc-pVTZ optimization.  Calculated and experimental nqcc's are compared in Tables 1 and 2.  Optimized structure parameters are given in Table 3, rotational constants in Table 4.
	In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's.
	Table 1.  14N nqcc's in trans-Cytosine (MHz).  Calculation was made on molecular structures given by (1) B3P86/6-31G(3d,3p) and (2) B3LYP/cc-pVTZ optimization.  Nitrogen numbering is given above in the figure.     Calc (1) Calc (2) Expt. [1]   N(1) Xaa - 2.640 - 2.640 - 2.6373(13) Xbb 1.226 1.208 1.1672(28) Xcc 1.414 1.432 1.4701(28) Xab - 2.029 - 2.086 Xac 0.002 0.002 Xbc 0.006 0.005   RMS 0.047 (2.7 %) 0.033(1.8 %)   N(3) Xaa 2.290 2.336 2.2619(20) Xbb - 3.624 - 3.672 - 3.6570(22) Xcc 1.334 1.336 1.3951(22) Xab - 0.233 - 0.233 Xac 0.017 0.018 Xbc 0.005 0.004 RMS 0.043 (1.8 %) 0.055 (2.3 %) N(8) Xaa 2.087 2.199 2.2167(17) Xbb 1.960 2.009 1.9511(20) Xcc - 4.047 - 4.208 - 4.1678(20) Xab 0.160 0.179 Xac - 1.035 - 0.820 Xbc - 0.239 - 0.173   RMS 0.102 (3.7 %) 0.042 (1.5 %)
	Table 2.  14N nqcc's in cis-Cytosine (MHz).  Calculation was made on molecular structures given by (1) B3P86/6-31G(3d,3p) and (2) B3LYP/cc-pVTZ optimization.  Nitrogen numbering is given above in the figure.     Calc (1) Calc (2) Expt. [1]   N(1) Xaa - 2.822 - 2.818 - 2.8007(18) Xbb 1.074 1.063 1.0340(27) Xcc 1.749 1.755 1.7667(27) Xab - 2.255 - 2.305 Xac 0.002 0.002 Xbc 0.003 0.003   RMS 0.028 (1.5 %) 0.021(1.1 %)   N(3) Xaa 2.273 2.319 2.2371(23) Xbb - 3.331 - 3.379 - 3.3890(25) Xcc 1.058 1.060 1.1519(25) Xab - 0.090 - 0.098 Xac 0.014 0.016 Xbc 0.002 0.001 RMS 0.067 (2.9 %) 0.071 (3.1 %) N(8) Xaa 2.078 2.206 2.2237(17) Xbb 1.989 2.051 1.9832(20) Xcc - 4.067 - 4.257 - 4.2069(20) Xab 0.163 0.186 Xac - 1.058 - 0.821 Xbc - 0.314 - 0.225   RMS 0.116 (4.2 %) 0.049 (1.7 %)
	Table 3. Cytosine.  B3P86/6-31G(3d,3p) and B3LYP/cc-pVTZ optimized structure parameters (Å and degrees).   trans  C  N,1,B1  C,2,B2,1,A1  C,3,B3,2,A2,1,D1,0  C,4,B4,3,A3,2,D2,0  N,1,B5,2,A4,3,D3,0  H,3,B6,2,A5,1,D4,0  H,4,B7,3,A6,2,D5,0  O,1,B8,2,A7,3,D6,0  H,9,B9,1,A8,2,D7,0  N,5,B10,4,A9,3,D8,0  H,11,B11,5,A10,4,D9,0  H,11,B12,5,A11,4,D10,0       B3P86     B3LYP  B1=1.33176409  B2=1.33726757  B3=1.3769012  B4=1.40602979  B5=1.32418979  B6=1.08747424  B7=1.0827569  B8=1.33865157  B9=0.96637312  B10=1.36256839  B11=1.00826248  B12=1.00605494  A1=114.49025526  A2=123.50419607  A3=116.07872726  A4=128.4501019  A5=115.92568971  A6=121.82030618  A7=116.45785973  A8=105.48312518  A9=122.04257434  A10=115.41050172  A11=118.43838067  D1=-0.1413457  D2=0.14838331  D3=-0.16233264  D4=179.90592019  D5=-179.54210511  D6=-179.86991518  D7=-0.06444788  D8=-177.77552501  D9=-166.38608126  D10=-21.4390202  B1=1.33118273  B2=1.33838464  B3=1.37597607  B4=1.40790975  B5=1.32454107  B6=1.08407963  B7=1.07985081  B8=1.34388602  B9=0.96634972  B10=1.3608087  B11=1.00545686  B12=1.00317905  A1=114.80329631  A2=123.34621137  A3=116.24728948  A4=128.02712761  A5=116.11714657  A6=121.73410878  A7=116.68547747  A8=106.02627441  A9=122.1371945  A10=116.75246945  A11=119.78971242  D1=-0.1021715  D2=0.07173595  D3=-0.12853005  D4=179.92049474  D5=-179.57017982  D6=-179.8975806  D7=-0.02507294  D8=-178.26608817  D9=-169.50474398  D10=-16.77852188     cis  C  N,1,B1  C,2,B2,1,A1  C,3,B3,2,A2,1,D1,0  C,4,B4,3,A3,2,D2,0  N,1,B5,2,A4,3,D3,0  H,3,B6,2,A5,1,D4,0  H,4,B7,3,A6,2,D5,0  O,1,B8,2,A7,3,D6,0  H,9,B9,1,A8,2,D7,0  N,5,B10,4,A9,3,D8,0  H,11,B11,5,A10,4,D9,0  H,11,B12,5,A11,4,D10,0       B3P86     B3LYP  B1=1.32506801  B2=1.33677599  B3=1.3787032  B4=1.40372592  B5=1.33179755  B6=1.08780311  B7=1.08278496  B8=1.33886741  B9=0.96579945  B10=1.36434218  B11=1.00819689  B12=1.00638182  A1=114.07672341  A2=124.05051439  A3=116.09791825  A4=128.40119588  A5=115.69883636  A6=121.89664438  A7=115.50866232  A8=106.01649026  A9=122.24639175  A10=115.41069432  A11=117.93873474  D1=-0.13142323  D2=0.19713078  D3=-0.2446351  D4=179.90412971  D5=-179.52121386  D6=-179.96814658  D7=-179.7605362  D8=-177.71030932  D9=-165.27016387  D10=-22.0883644  B1=1.32479505  B2=1.33729568  B3=1.37774992  B4=1.40521696  B5=1.33185242  B6=1.08420642  B7=1.0796612  B8=1.34394064  B9=0.96568737  B10=1.36173556  B11=1.00505431  B12=1.00314746  A1=114.38631641  A2=123.89625574  A3=116.29160551  A4=127.99229176  A5=115.88958077  A6=121.76247879  A7=115.69145121  A8=106.55525794  A9=122.39951366  A10=116.98934651  A11=119.54937601  D1=-0.08433136  D2=0.09012435  D3=-0.19063797  D4=179.90899979  D5=-179.57841032  D6=-179.96860067  D7=-179.82752601  D8=-178.27982923  D9=-168.96047155  D10=-16.81122491
	Table 4.  Cytosine.  Rotational Constants (MHz).  Calc on (1) B3P86/6-31G(3d,3p) and (2) B3LYP/cc-pVTZ optimized molecular structure. Calc (1) Calc (2)   Expt. [1]    trans A   3978.   3975. 3951.85325(32) B   2019.   2011. 2008.95802(12) C   1340.   1336. 1332.47228(8)    cis A   3909.   3906. 3889.46510(38) B   2039.   2032. 2026.31804(12) C   1341.   1337. 1332.86951(10)
	[1] J.L.Alonso, V.Vaquero, I.Peña, J.C.López, S.Mata, and W.Caminati, Angew.Chem. 125,2387(2013).
	Pyrimidine		Aniline		Purine		Uracil
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						Last Modified 18 March 2016