Complexing Behaviour and Antifungal Activity of N-[(1E)-1-(1H-Benzimidazol-2-yl)ethylidene]morpholine-4-carbothiohydrazide and Related Ligand with Metal Ions

The coordination complexes of bivalent metal ions with N-[(1E)-1-(1H-Benzimidazol-2-yl)ethylidene]morpholine-4-carbothiohydrazide (H2bmctz, H2L-1) and N-[(1E)-1-(1H-Benzimidazol-2-yl)(phenyl)methylidene] morpholine-4-carbothiohydrazide (H2bpmctz, H2L-2) were prepared and their neutral, monoanionic, and dianionic forms of ligands of compositions [M(H2L)X2] (M=CoII, NiII, CuII, ZnII, CdII, or PdII, X=Cl− or Br−, and H2L=H2L-1 or H2L-2), [M(HL)2]nH2O where (M=CoII, CuII, MnII, NiII, ZnII or CdII, H2L=H2L-1 or H2L-2, and n = 0 or 2), and [MLB]nB (M=CuII, NiII, ZnII, CdII, or PdII, B=H2O, Py, or Y-pic, n = 0 and n = 1 if B=H2O for Ni(II) and H2L=H2L-1 or H2L-2) have been characterised by magnetic susceptibility measurements, electrical conductance values, and spectral properties. The magnetic moment value of [M(HL2)] (M=MnII, NiII, FeII or CuII) type complexes is consistent with high spin octahedral structure while those of [M(H2L)X2] (M=CoII, NiII, CuII, ZnII, or CdII, X=Cl− or Br−) possess five coordinated trigonal bipyramidal geometry. The adduct complexes [MLB]·nB (M=NiII, or CuII, B=H2O, Py, or Y-pic) are four coordinated planar and those of ZnII and CdII complexes [MLB], (H2L=H2L-1 or H2L-2, B=H2O, Py or Y-pic) are tetrahedral. These ligands have been suggested to coordinate as tridentate (N N S) donor molecule in complexes of type [M(H2L)X2], [M(HL)2], and [MLB]. The antifungal activity of ligands and some of their metal complexes were studied and it was observed that metal complexes show higher activity than free ligand