Synthesis, characterization and X-ray structures of AMTT-type Schiff bases and two Cu^I complexes (AMTT = 4-amino-5-methyl-2H-1,2,4-triazole- 3(4H)-thione)

The reaction of 4-amino-5-methyl-2H-1,2,4-triazole-3(4H)-thione (AMTT) with 4-methylbenzaldehyde and 4-methoxybenzaldehyde in ethanol led to the iminic derivatives 4-(4-methylbenzylideneamino)-5-methyl-2H-1,2,4-triazole-3(4H)-thione (L1) and 4-(4-methoxybenzyl-ideneamino)-5-methyl-2H-1,2,4-triazole-3(4H)-thione (L2). The reaction of L1 with CuCl in the presence of triphenylphosphane as co-ligand in methanol/chloroform solution gave the Cu^I complex containing L1, [Cu(L1)(PPh₃)₂Cl]·0.5CH ₃OH·0.25CHCl₃ (1). Treatment of L2 with the same metal salt in a molar ratio of 1:1 in methanol and further addition of a solution of PPh3 in chloroform led to the complex [Cu(L2)(PPh₃) ₂Cl]·2.5CHCl₃ (2). The complexes and L1 were characterized by IR and NMR spectroscopy as well as by X-ray diffraction studies. In both complexes, the Schiff base ligand is coordinated to the copper ion through its sulfur atom. The other coordination sites around the copper ion are occupied by two triphenylphosphane molecules and one chloride ion. Therefore, each Cu^I ion is in a distorted tetrahedral environment. Crystal data for L1 at -100°C: space group P2₁/n with a = 720.5(1), b = 1140.6(1), c = 1426.3(2) pm, β = 91.25(1)°, Z = 4, R ₁ = 0.03, for 1 at -120°C : space group P1 with a = 1286.3(1), b = 1740.3(1), c = 2060.2(1) pm, α = 79.085(6), β = 83.827(5), γ = 76.688(6)°, Z = 4, R₁ = 0.0649 and for 2 at -80°C : space group P1 with a = 1183.7(2), b = 1370.1(2), c = 1812.1(3) pm, α = 85.69(2), β = 88.52(2), γ = 64.89(2)°, Z = 2, R₁ = 0.0488.