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Metal(II) complexes of the types [M(L)Cl2(H2O)] and [M(L')2Cl2] [M = Co(II), Ni(II), Cu(II) and Cd(II), L = acetophenone 4-aminobenzoylhydrazone (APABH), NH2C6H4CONHN=C(CH3)C6H5 and L' = 4-hydroxyacetophenone 4-aminobenzoylhydrazone (HAPABH), NH2C6H4CONHN=C(CH3)C6H4OH were prepared and characterized by elemental and thermal analyses, molar conductance, magnetic susceptibility, infrared, NMR and electronic spectral studies. Some of the complexes were screened against E. coli, and Aspergillus niger for biological activity. The antibacterial activity of hydrazones and their complexes increases with increase of the concentration of solutions. At each concentration copper(II) complexes are more active than the Zinc(II) complexes with both hydrazones. The antifungal activity of the complexes is less than their parent ligands.

Metal(II) complexes of the types [M(L)mCl2(H2O)n] and [Cu(L')SO4(H2O)2] [M=Co(II), Ni(II), Cu(II) and Cd(II), L=acetophenone salicyloylhydrazone (ASH) OHC6H4CONHN=C(CH3)C6H5, m=2, n=2; 4-hydroxyacetophenone salicyloylhydrazone (4-HOASH), m=2, n=0; acetophenone isonicotinoylhydrazone (AINH), NC5H4CONHN=C(CH3)- C6H5, m=1, n=2; 4-hydroxyacetophenone isonicotinoylhydrazone (4-HOAINH), NC5H4CONHN=C(CH3)C6H4OH, m=1, n=2, and L'=4-HOAINH and 4-HOASH] were prepared and characterized by elemental and thermal analyses, molar conductance, magnetic susceptibility, infrared, electronic, NMR, ESR and X-ray powder diffraction studies. Some of the complexes were screened against E. coli and Aspergillus niger to explore their biological activity.

Lanthanide complexes of the types Ln(sah)(OAc)·xH2O and Ln'(Hsah)2(X)·xH2O [Ln=Y, La, Nd, Gd, Tb and Dy; Ln'=Pr and Sm, X=NO3 and Cl; H2sah=salicylaldehyde anthranoyl hydrazone were synthesized and characterized by various physico-chemical techniques. The complexes are coloured and highly soluble in methanol, DMSO and DMF. Dehydration studies indicate the presence of both lattice-held and coordinated water molecules. IR, electronic and 1H NMR spectra have been recorded to establish the bonding sites of the ligand. Solution-state conductance measurements indicate the non-electrolytic nature of all of the complexes while solid-state electrical conductivity studies show Nd(sah)(OAc)·4H2O to be a semiconductor. Optical band gap measurements show the Pr, Sm and Dy complexes are direct band gap materials. X-ray diffraction patterns of selected complexes indicate orthorhombic structures.

Metal(II) complexes of the types [M(L)2Cl2]·H2O and [Cu(4-HOABH)SO4(H2O)2] [M═Co(II), Ni(II), Cu(II) and Cd(II), L=acetophenone benzoylhydrazone (ABH), C6H5CONHN = C(CH3)C6H5 and 4-hydroxyacetophenone benzoylhydrazone (4-HOABH), C6H5CONHN = C(CH3)C6H4OH], were prepared and characterized by elemental and thermal analyses, molar conductance, infrared, ESR and electronic spectral studies. Some of the complexes were screened against E. coli and Aspergillus niger for biological activity.

The complexes [M(L1)nCl2] and [Cu(L2)SO4(H2O)2] [M= Co(II), Ni(II), Cu(II) and Cd(II); L1=acetophenone oxaloyldihydrazone (CONHN═C(CH3)C6H5)2, n=2 and L2=4-hydroxyacetophenone oxaloyldihydrazone (CONHN= C(CH3)C6H4OH-4)2 have been prepared. Analytical, molar conductance, magnetic susceptibility, electronic, ESR and NMR spectral data have been used to investigate the structure and bonding of the complexes. X-ray powder diffraction data indicate the shape and size of the unit cell of the copper(II) complex. Some of the complexes were screened against E. coli and Aspergillus niger for biological activity.

Acetylacetone mono-benzoylhydrazone, PhCONHN=C(Me)CH2C(Me)O (LH), and acetylacetone mono-isonicotinoylhydrazone, NC5H4CONHN =C(Me)CH2C(Me)O (L'H), complexes of the type [ML2] and [ML2'] (M=Co(II), Ni(II), Cu(II) or Zn(II)) have been prepared and characterized. The ligands form monobasic, four-coordinate complexes and chelate via enolate and imine. The E.S.R. spectra of the Cu(II) complexes suggest a square coplanar stereochemistry.

Aluminum(III) complexes of the type [AlL2X2]X˙n H2O where L = isonicotinoyl hydrazine (INH), NC5H4CONHNH2, salicyloyl-hydrazine (SH), HOC6H4CONHNH2, oxaloyldihydrazine (ODH), (CONHNH2)2, and malonoyldihydrazine (MDH), CH2(CONHNH2)2; X = CL-, NO3-, SCN- and 1/2 SO42-; n = 0-3, were prepared and characterized with the help of elemental analyses, solution and solid state conductance, thermal decomposition and infrared spectral studies. All the complexes are insoluble in common organic solvents and most of them are stable upto 300°C, above which they show stepwise decomposition patterns. Solid state conductance data at room temperature suggest semiconducting properties of the complexes. IR spectra indicate that the ligands bond to the metal atom through >C=O and -NH2 groups. X-ray diffraction parameters of [Al(SH)2Cl2]Cl. 2H2O and [Al(INH)(NO3)2]NO3˙2H2O correspond to orthorhombic and tetragonal crystal lattices, respectively. The ligands as well as their complexes show moderate antifungal and antibacterial activity.

MCu2(SCN)4.L complexes, where M = Ni(II), Co(II) and L = benzoic acid hydrazide (BH), salicylic acid hydrazide (SH), isonicotinic acid hydrazide (INH) and their isopropanone derivatives viz. isopropanone-benzoylhydrazone (IBH), -salicyloylhydrazone (ISH), and -isonicotinoylhydra zone (IINH), were synthesised and characterized with the help of elemental analyses, electronic, and I.R. spectral, thermal, magnetic moment and solid state conductance data. The complexes are soluble in DMF and DMSO, dissociate in H2O and C2H5OH but are insoluble in other organic solvents and decompose above 190°C.

A series of metal(II) hydrazine-azides of the type M(N2H4)x(N3)yCl2-y, where × = y = 1 or 2; M = Co(II), Ni(II), Zn(II) and Cd(II), have been prepared and characterized by elemental analyses, magnetic susceptibility data, electronic and infrared spectra. The cobalt(II), nickel(II), zinc(II) and cadmium(II) complexes are stable solid powders at room temperature but explode or give sparks on heating. Attempts to isolate the manganese(II), iron(II) and copper(II) complexes were unsuccessful. All the complexes are insoluble in common organic solvents as well as in DMF and DMSO. Electronic spectral bands for the cobalt(II) complexes between 8500-19050 cm-1 and nickel(II) complexes between 10300-16400 cm-1 and their μeff values around 4.9 and 3.3 B.M., respectively, correspond to those observed for octahedral geometry. IR spectra of the complexes indicate a monodentate bonding or bridging character for both N2H4, and N3- groups depending on the composition and the metal.

Complexes of the type MLX2 where M = Cu(II), Ni(II), Co(II), Mn(II), Zn(II), Cd(II), Hg(II), VO(IV), ZrO(IV) and UO2(VI), L = glyoxalmonoisonicotinoyl hydra zone, X = Cl, NO3 and ½ SO4 have been synthesized and characterized by elemental analyses, physico-chemical and solid state conductance studies. The complexes are stable and insoluble except in DMF, DMSO and decompose above 200°C without melting. The Cu(II), Ni(II), Co(II) and Mn(II) complexes are paramagnetic, have distorted octahedral stereochemistry and show semiconducting properties in the solid state. The ligand bonds to the metal ions through [image omitted]  groups. The Cu(II), Ni(II), Co(II), Zn(II), Cd(II) and Hg(II) complexes were screened against Synechococcus elongatus, a nitrogen fixing blue green algae, showing a significant inhibition of growth, protein and chlorophyll synthesis in contrast to the ligand. The inhibition varies with the metal ion in the order Hg > Cd > Co > Ni > Zn > Cu in algal growth and Hg > Cd > Co > Zn > Ni ∼ Cu in protein synthesis and Hg > Cd > Co∼Ni∼Cu in chlorophyll synthesis.

Complexes of the title ligands having the general composition MCl2L.xH2O where M = Cu(II), Ni(II), Co(II), Zn(II), Cd(II), Hg(II), L = glyoxalimine oxamide (GODH), glyoxalimine malonamide (GMDH) and x = 0, 1, 2, were synthesised. These were prepared either by solid-solution reaction of the metal chloride and the preformed polymeric ligands derived from glyoxal and oxaldihydrazide/malondihydrazide or by template synthesis using metal chloride, glyoxal, oxaldihydrazide/malondihydrazide in 1:1:1 molar ratio. The complexes are intensely coloured and highly insoluble in water as well as polar and non-polar organic solvents. They decomposed above >350°C without melting and were characterized by elemental analyses, magnetic, electronic and infrared spectral data, thermal (TG, DTG and DTA) and solid state conductance studies.The complexes in the solid state show water molecules in the lattice structure or coordination sphere, anomalous magnetic moments, square or distorted octahedral stereochemistry and semiconducting properties. The ligands GODH and GMDH bond to the metal ions through >C=N groups. The complexes show an overall endothermic decomposition.

Mercuration reactions of sulfadrugs(1:1 mole ratio), using mercuric oxide and glacial acetic acid, have been carried out with sulfanilamide (SN), sulfaguanidine(SG), sulfathiazole (ST), sulfapyridine(SP), sulfadiazine(SD), sulfamerazine (SM), sulfamethazine (SZ), succinylsulfathiazole(SST) and phthalylsulfathiazole(PST). The resulting complexes were characterized by analyses and infrared spectral studies. Mercuration by electrophilic substitution occurs on benzene ring in sulfanilamide and sulfaguanidine whereas in the other drugs it occurs in the heterocyclic ring.

Chromium (III)-oxaldihydrazide-azide complexes of the type Cr(ODH)x (N3)y (12SO4)3-y.6H2O, where x and y=1-3 and ODH = oxaldihydrazide, were synthesized. The complexes were characterized by elemental analysis, IR and electronic spectral and magnetic data, and studied for their weight loss (between 40-180°C) and solid state conductance. The complexes are insoluble in water and common polar and non-polar solvents, paramagnetic and semiconductors. Water molecules are partly coordinated and partly in the lattice. The sulphate and azide are ionic and ODH bonds to octahedral Cr(III) via -NH2 groups.

Nickel (II) complexes of the type Ni[Ag(SCN)2]2.L [where L = benzoic acid hydrazide (BH), salicylic acid hydrazide (SH), anthranilic acid hydrazide (AH), isonicotinic acid hydrazide (INH), oxaldihydrazide (ODH), malondihydrazide (MDH) and their isopropanone derivatives, viz., isopropanone benzoyl hydrazone (IBH),-salicyl-hydrazone (ISH), -anthranoylhydrazone (IAH) and -isonicotinoyl hydrazone (IINH)] were synthesised and characterized with the help of elemental analyses, electronic, IR and magnetic moment data. The complexes are insoluble in common organic solvents, partially dissociate or dissolve in DMF and DMSO, have coordinated hydrazide or hydrazone ligands and bridging SCN groups. Nickel (II) in the complexes is spin free and has a pseudo-octahedral environment.

The ligands N,N-diacetyloxaldihydrazide (DAODH), (CONHNHCOCH3)2, and N,N-diacetylmalondihydrazide (DAMDH), CH2 (CONHNHCOCH3)2, form 1:1 metal: ligand complexes of the types M(DAODH-2H).nH2O and M(HNMDH-2H).nH2O where M = Zn(II), Cu(II), Ni(II), Co(II) and n = 0, 1, 2. The complexes have been characterized by elemental analysis, electronic, IR and magnetic moment data. The complexes are insoluble in common organic solvents except Cu(DAODH-2H). 2H2O and Ni(DAODH-2H). 2H2O which are partially soluble in DMF and DMSO. Cu(II) complexes are square planar while Co(II) and Ni(II) complexes are octahedral. IR data show that both DAODH and DAMDH behave as tetradentate ligands bonding through C-O and N-H groups.

Polymeric complexes of the empirical composition Hg(L-H)Cl and Hg2 (L-2H)Cl2 [L = benzoylhydrzide (BH), oxaldihydrazide (ODH), malondihydrazide (MDH), isopropanone benzoylhydrazone (IBH), isopropanoneoxaldihydrazone (IODH) and isopropanonemalondihydrazone (IMDH)] have been prepared and characterized by analytical and infrared spectral data, X-ray powder diffraction and polarographic studies. Some of the complexes tested for antifungal and antibacterial activity are more active than the ligands.

A new series of bimetallic tetrathiocyanate complexes of the type MM'(SCN)4.L, M = Zn(II), Cu(II), Ni(II), Co(II), M' = Hg and L = benzoylhydrazide (BH), oxaldihydrazide (ODH) and malondihydrazide (MDH) have been synthesized in dilute ethanolic medium. The 1:1 metal:ligand complexes, which have been characterized by elemental analysis, magnetic moment data, electronic and infrared spectra, are insoluble in water as well as common organic solvents and decompose above 250°C without melting. The ligands act as bidentate coordinating species in the complexes. Some of these bimetallic complexes have been tested against Escherichia coli and Klebsillea pneumoniae bacteria and Aspergillus flavus, Penicillium sp. fungi, and were found to be biologically active.

Chromium(III) malondihydrazide azide/sulphate complexes of the type [image omitted] , where x = y = 1-3 and MDH = malondihydrazide, CH2(CONHNH2)2 have been synthe-sised and characterized by elemental analyses. All the complexes are insoluble in water and polar/non-polar common organic solvents. Electronic spectral and magnetic moment data indicate octahedral stereochemistry around chromium(III) in all complexes. MDH bonding occurs only through the two imino NH groups as indicated by the IR spectra. The azide and sulphate groups are ionically associated. The absence of sharp lines in the XRD patterns of two complexes indicate their micro crystalline character.

A series of chromium(IIl) benzoyl hydrazine a zide/sulphate complexes of the type Cr(BH)x(N3)y(SO4)3y.6H2O where BH = benzoyl-hydrazine, C6H5CONHNH2, and x, y = 1-3 have been prepared and characterized by elemental analyses, weight loss, IR and electronic spectra, solution and solid state conductance and magnetic suscepti data. The complexes are paramagnetic and have octahedral stereochemistry with BH bonds to Cr(III) through >C=O and -NH2 groups. N3- and SO4- groups are ionically associated. Dehydration studies show stepwise elimination of water molecules. The molar conductance values of some of the complexes are low. Solid state conductance between 1.4 × 10-8 to 18.16 × 10-8 (ohm cm)-1 varying with the number of N3- groups and frequency, indicates a semiconducting nature of the complexes at room temperature. BH, NaN3, K2SO4Cr2(SO4).24H2O and four of Cr(III) complexes were screened against Synechococcus cedrorum, e unicellular non-nitrogen fixing, mesophilic blue green alga, and have shown significant inhibition of chlorophyll - a, carotenoids, phycocyanin, carbohydrate, protein and biomass production. The following trends have been observed NaN3 > BH > K2SO4Cr2(SO4)3.24H2O > Cr(BH)2(N3)2 xSO4.6 H2O, Cr(BH3)3(N3)(SO6).6H2O > Cr(BH)3(N3)2.xSO4.6 H2O > Cr(BH)3(N3)3.6H2O.

Chromium(III) complexes of the type [crL2X2] X.nH2O, where L = benzoylhydrazine (BH), isonicotinoylhydrazine (INH), salicyloyl-hydrazine (SH), malonoyldihydrazine (MDH) and oxaloyldihydrazine (ODH); X = CH3COO- (OAc), SCN- or ½ SO42- and [cr(BH)3]x3.nH2O, where X = CH3COO- (OAc) or SCN-, were prepared and characterized with the help of elemental analyses, magnetic moments, molar and solid state conductances, thermal (TG and DTA) studies, IR and electronic spectral data. The complexes, which are insoluble in common organic solvents, decompose above 300°C and are high spin octahedral with the mono-acylhydrazines bonding through >C=O and -NH2 and the dihydrazines only through the two -NH2 groups. The complexes show multistep exothermic decomposition patterns. X-ray powder diffraction studies of selected complexes yield patterns indicative of possiole polymeric structures. The ligancis as well as their complexes show some antifungal and antibacterial activity.

Iron(III) complexes of the type [FeL2 X2]x-nH2O, where L = benzoylhydrazine (BH), isonicotinoylhydrazine (INH), sali-cyloylhydrazine (SH), oxaloyldihydrazine (ODH) and malonoyl-dihydrazine (MDH); X = Cl-, NO3, SCN- and 1/2 SO4 2-; n =0-3, were prepared and characterized with the help of elemental analyses, molar and solid state conductance, thermal, magnetic, infrared and electronic spectral studies. The complexes are highly insoluble in common organic solvents, decompose above 200°C and are spin free octahedral. The ligands coordinate to the metal atom through >C=O and NH2- The complexes show multi-step exothermic decomposition patterns. The ligands as well as their complexes show moderate antifungal and antibacterial activity.

Complexes of the title ligands (Schiff bases) viz. valeral-dehyde benzoyl hydra zone, CH3(CH2)3CH = NNHCOC6H5, (VBH), and valeraldehyde isonicotinoylhydrazone, CH3(CH2)3CH = NNHCOC5N, (VINH), of the general composition [ML2C12J xH2O (where M = Co(II), Ni(II), Cu(II) and Zn(II); L = VBH and VINH and x = 0-3) Were prepared and characterized by elemental analyses, infrared, electronic and ESR spectra, magnetic moments, molar conductance and X-ray diffraction data. The complexes are spin free pseudo-octahedral and the ligands bond to the metal ion via >C=O and >C=N- groups. The ESR spectra of the Cu(II) complexes indicate a dimeric, tetragonally distorted octahedral stereochemistry. Lattice constants of the Cu(Il) and Co(II) complexes indicate an orthorhombic microcrystalline structure. The complexes show moderate activity against fungi and bacteria.

A series of metal (II) benzoylhydrazine-azide complexes of the type M(BH)(N3)2.3H2O where M = Co(II), Ni(II), Zn(II), Cd(II) and BH = benzoylhydrazine, C6H5, C6H5NH2, have been prepared and characterized by elemental analyses, magnetic susceptibility, electronic and IR spectral data. The complexes are highly insoluble, powdery materials and decompose without melting. Co(II) and Ni(II) complexes are paramagnetic and octahedral. BH acts as a bidentate ligand coordinating through >C=O and -NH2 groups. BH, Co(BH)(N3)2.3H2O and Ni(BH)(N3)2.3H2O, screened against cyanobacteria Synechococcus cedrorum, a unicellular, non-nitrogen fixing mesophilic blue green algae, show moderate inhibition of algal growth and formation of protein, carbohydrate and photosynthetic pigments (chlorophyll-a, carotenoids, phycocyanin). Carbon fixation studies, using 14C labelled NaHCO3 solution indicate that carbon fixation occurs in the order: Co(BH)(N3)2.3H2O> Ni(BH)(N3)2.3H2O > BH. The three compounds catalyse the photodecomposition and enhance the oxygen evolution during the photosynthesis in the order: Ni(BH)(N3)2.3H2O > BH.

Cobalt(II) complexes of the type [Co(L)2(H2O)2]X2, where L = benzoylhydrazine, C2H4CONHNH2 (BH) or isonicotinoylhydrazine, NC5H4CONHNH2 (INH); × = Cl-, NO3- and ½SO42- and [Co(BH)3]X2.nH2O, where × = Cl- and NO3- and n = O or 3, were synthesized and characterized by elemental analyses, molar conductance, magnetic moments and electronic and IR spectra. All the complexes are 1:3 electrolytes and soluble in water, ethanol, DMF and DMSO. The complexes are spin-free octahedral and the ligands bond to the metal ion via >C=O and NH2 groups. Dehydration studies indicate the presence of coordinated water molecule in most of the complexes. X-ray powder diffraction parameters for some of the complexes correspond to a tetragonal crystal lattice. The complexes show a fair degree of antifungal activity against a number of pathogenic fungi viz. Alternaria tenuissima, A. alternata, A. triticina, A. brassicae, A. sesami, Curvularia lunata, Pseudocercospora sp., Colletotrichum capsici, Fusarium oxysporum udam, F. oxysporum lini and Helminthosporum sativum.

Copper(II) complexes of the type CuAg2(SCN)4˙L (where L = benzoylhydrazine (BH), p-hydroxybenzoylhydrazine (PHBH), salicyloylhydrazine (SH), isonicotinoylhydrazine (INH), anthraniloylhydrazine (AH) and their isopropanone derivatives viz., isopropanone benzoylhydrazone (IBH), -salicyloylhydrazone (ISH), -anthraniloylhydrazone (IAH), and -isonicotinoylhydrazone (IINH) have been synthesized and characterized with the help of elemental analyses, electronic and IR spectra and magnetic moment data. Electronic spectral bands and μeff values suggest a distorted octahedral environment around copper(II). SCN groups act as bridge between two metal centres while all the ligands are bi-coordinately bonded through >C=O and -NH2 or >C=N-groups, except in CuAg2 (SCN)4˙L (L = INH and IINH) where the ligands are coordinated through -NH2/-N=C< and pyridyl ring nitrogens. Powder ESR data suggest an isotropic nature of all the complexes except for CuAg2 (SCN)4.SH where an axial nature of copper(II) is observed. Presence of half field signal in CuAg2 (SCN)4.PHBH complex suggests its dimeric nature. Powder X-ray diffraction studies for CuAg2(SCN)4 and CuAg2 (SCN)4. IBH suggest the presence of orthorhombic and tetragonal crystal lattice respectively.

Cobalt(II) complexes of the type CoAg2(SCN)4-L (where L = benzoic acid hydrazide (BH), salicylic acid hydrazide (SH), anthraniiic acid hydrazide (AH), isonicotinic acid hydrazide (INH) and their isoproparcne derivatives viz. isopropanone benzoyl hydrazone (IBH), -salicoyl hydrazone (ISH), -anthranoyl hydrazone (IAH) and -isonicotinoyl hydrazone (IINH) were synthesised and characterized with the help of elemental analyses, electronic and IR spectra and magnetic moment data. The complexes are insoluble in common organic solvents but partially dissolve in DMSO and DMF. Cobalt(II) in the complexes has spin-free tetragonally distorted octahedral geometry. All the ligands are bicoordinate, bonding through >C=O and -Nh2 or >C=N- groups except INH and IINH, where the pyridyl ring nitrogen and -NH2 or -N=C> groups participate in bonding. SCN groups act as a bridge between two metal centres. Solid state conductance values suggest the semiconducting nature of the complexes. Thermal studies (TG, DTG and DTA) on CoAg2(SCN)4, CoAg2(SCN)4-BH and CoAg2(SCN)4.IBH indicate multiple decomposition steps which are both exothermic and endothermic.

Complexes of the type Na6[M(HL)2(H2O)2], where M= Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) and Na3H2L= 2-(4-sulphophenylazo)-1,8-dihydroxy 3,6 naphthalene disulphonic acid trisodium salt, have been synthesized and characterized by physico-chemical (elemental analyses, solubility, electrolytic conductance, magnetic susceptibility measurement) and spectral (UV-Visible, IR, ESR, powder x-ray diffraction) techniques for their structure and studied for their antifungal activity against ten fungi. The anionic 1:2 metal:ligand complexes show octahedral geometry around M(II), a significant antifungal activity against Curvularia lunata and Alternaria triticina and a moderate activity against Alternaria brassicicola, Alternaria brassicae, Alternaria solanae, Curvularia species, Helminthosporium oryzae, Collectotrichum capsici, Aspergillus niger, Aspergillus flavus and Fusarium udum.

In refluxing ethanol, the equimolar reaction of corresponding bivalent transition metal salts with the finely powdered acylhydrazones derived from 3‐hydroxy‐2‐naphthaldehyde and benzoyl or salicyloyl hydrazine leads to complexes of the type (I), which are highly insoluble in common organic solvents.