Structural and spectral studies of N-(2-pyridyl)-N′-(4-substituted phenyl)thioureas

The following molecules were found to have intramolecular hydrogen bonding between the N'H and the pyridine nitrogen and intermolecular hydrogen bonding between the NH and a thione sulfur of a second molecule to form dimers: N-(2-pyridyl)N'-(4-methoxyphenyl)thiourea, PyTu4OMe, triclinic, P-1, a = 7.158(4), b = 8.742(3), c = 10.833(4) Angstrom, alpha = 70.53(3), beta = 74.38(3), gamma = 73.97(4)degrees, V = 635.5(5) Angstrom(3) and Z = 2; N-(2-pyridyl)-N'-(4-nitrophenyl)thiourea, PyTu4NO(2), monoclinic, P2(1)/ c, a = 11.670(1), b = 5.9225(9), c = 18.792(4) Angstrom, beta = 107.99(1)degrees, V = 1244.8(7) Angstrom(3) and Z = 4; N-(2-pyridyl)-N'-(4-chlorophenyl)thiourea, PyTu4Cl, triclinic, P-1, a = 9.939(3), b = 11.399(4), c = 12.264(5) Angstrom, alpha = 65.50(4), beta = 87.46(3), gamma = 76.63(3)degrees, V = 1228.1(7) Angstrom(3) and Z = 4 and N-(2-pyridyl)-N'-(4-bromophenyl)thiourea, PyTu4Br, triclinic, P-1, a = 10.020(2), b = 11.444(2), c = 12.353(5) Angstrom, alpha = 64.76(2), beta = 87.61(3), gamma = 77.88(2)degrees, V = 1250.8(7) Angstrom(3) and Z = 4. The methoxy and nitro moieties of PyTu4OMe and PyTu4NO(2) also interact with N'H and there is a weak intermolecular interaction between one of the pyridine hydrogen atoms and the thione sulfur in PyTu4Br. Solution H-1 NMR spectral studies (DMSO-d(6)) show the N'H resonance considerably downfield for each thiourea and its chemical shift, as well as that of NH, is affected by substituents on the phenyl ring. (C) 2002 Elsevier Science B.V. All rights reserved.