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) A , α=70.53(3), β=74.38(3), γ=73.97(4)°, V=635.5(5) A 3 and Z=2; N-(2-pyridyl)-N′-(4-nitrophenyl)thiourea, PyTu4NO2, monoclinic, P21/c, a=11.670(1), b=5.9225(9), c=18.792(4) A , β=107.99(1)°, V=1244.8(7) A 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) A , α=65.50(4), β=87.46(3), γ=76.63(3)°, V=1228.1(7) A 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) A , α=64.76(2), β=87.61(3), γ=77.88(2)°, V=1250.8(7) A 3 and Z=4. The methoxy and nitro moieties of PyTu4OMe and PyTu4NO2 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 1H NMR spectral studies (DMSO-d6) 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.