Structural studies of N(4)-substituted thiosemicarbazones prepared from 4-formylantipyrine and a thiourea derived from 4-aminoantipyrine

Reaction of 4-formylantipyrine with N(4)-dimethylthiosemicarbazide and 3-piperidylthiosemicarbazide produces the N(4)-dimethylthiosemicarbazone (1), and the 3-piperidylthiosemicarbazone (2), respectively. Compound 1 is triclinic, space group P-1 with a = 6.329(1) Å, b = 11.699(1) Å, c = 11.943(1) Å, α = 65.83(1)°, β = 80.83(1)°, γ = 84.90(1)°, and V = 796.1(1) ų with Z = 2, for D _calc = 1.324 g/cm³. Compound 2 is triclinic, space group P-1 with a = 6.784(1) Å, b = 10.485(2) Å, c = 13.462(3) Å, α = 102.05(2)°, β = 98.61(2)°, γ = 101.32(2)°, and V = 899.8(5) ų with Z = 2, for D_calc = 1.319 g/cm³. Reaction of 4-aminoantipyrine with phenyl isothiocyanate produced N-antipyrine-N′-phenylthiourea (3). Compound 3 is monoclinic, space group P2₁/n with a = 6.863(7) Å, b = 15.361(3) Å, c = 16.332(5) Å, β = 90.35(6)°, and V = 1720.7(18) Å ³ with Z = 4, for D_calc = 1.306 g/cm³. Compounds 1 and 2 have intermolecular hydrogen bonding between the carbonyl oxygen of the antipyrine moiety and the NH hydrogen of the thiosemicarbazone moiety. In 3 the two unique molecules are held together as a dimer by interactions of the two thiourea NH's and the antipyrine moiety's oxygen.