Structural, spectral and thermal studies of N-2-(4,6-lutidyl)-N′-chlorophenylthioureas

N-2-(4,6-lutidyl)-N'-2-chlorophenylthiourea, 4,6LutTu2ClPh, triclinic, P-1, a = 7.512(1), b = 7.695(2), c = 12.870(3) Angstrom alpha = 82.50(2), beta = 77.07(2), gamma = 83.50(2)degrees, V = 716.2(3) Angstrom(3) and Z = 2; N-2-(.4,6-lutidyl)-N'-3-chlorophenylthiourea, 4,6LutTu3ClPh, monoclinic, C2/c, a = 25.162(3), b = 7.220(4), c = 16.272(2) Angstrom, beta = 94.71 (1)degrees, V = 2946.0(2) Angstrom(3) and Z = 8 and N-2-(4,6-lutidyl)-N-4-chlorophenylthiourea, 4,6LutTu4ClPh, monoclinic, C2/c, a = 33.1254(15), b = 4.3025(1), c = 20.3298(9) Angstrom, beta = 107.070(10)degrees, V = 2769.80(19) Angstrom(3) and Z = 8. The strength and nature of the intramolecular hydrogen bonding between N'H and the pyridine nitrogen and intermolecular hydrogen bonding involving the thione sulfur and the NH hydrogen are affected by the position of the chloro substituent on the phenyl ring. N'H is bifurcated in 4,6LutTu2Cl interacting with the chlorine (and the pyridine nitrogen), and the aromatic hydrogens interact weakly with sulfur and chlorine in neighboring molecules in these thioureas. The enthalpies of fusion and melting points are in the order 4,6-LutTu4Cl much greater than 4,6LutTu2Cl > 4,6LutTu3Cl. H-1 NMR studies in CDCl3 show the N'H hydrogen resonance considerably downfield from other resonances in the spectrum for each thiourea. (C) 2002 Elsevier Science B.V. All rights reserved.