N. Ray Chaudhuri

Acid hydrazides as ligands—III: Metal complexes of acetylhydrazide and benzoymhydrazide

Abstract Metal complexes of acetylhydrazide and benzoylhydrazide are reported. I.R. spectra of the normal and deuterated complexes, visible spectra of both solids and solutions, u.v. spectra, magnetic data and conductance data are discussed. Monodentate character and “imidol” structure of the ligands, in the complexes are suggested. The NH nitrogen atom is proved to be the coordination site.

Metal complexes of malondihydrazide

Abstract Metal complexes of malondihydrazide have been studied. Manganese, iron, cobalt, nickel, copper, zinc, palladium, silver, cadmium and lead complexes of four different compositions have been isolated. Characterization of the complexes by i.r., visible and u.v. spectra, conductance and magnetic data has been carried out. This bidentate ligand co-ordinates through the secondary nitrogen atoms. The structure of the complexes are discussed.

Thermal investigation of diamine complexes of nickel(II) in the solid phase

Abstract Thermal investigations have been carried out on [NiL 2 X 2 ]· n H 2 O, where L= N,N -diethylethylenediamine, X = Cl − , SCN − or CCl 3 COO − and n = 2 or 0, [NiL 2 (H 2 O) 2 ]Br 2 and [NiLX 2 (H 2 O) 2 ], where X = CH 3 COO − . All the complexes are characterized by elemental analyses, magnetic and spectral [IR and electronic(mull)] data. All the complexes possess O h symmetry. They generate several thermally isolable as well as non-isolable complex species as intermediates upon heating. Some of the intermediate species lose their original symmetry and attain either square planar or T d symmetry. A unique feature is observed in the case of [NiL 2 (CCl 3 COO) 2 ] which on heating first transforms to [NiL 2 CO 3 ] and then to NiCO 3 through the transformation of several non-isolable intermediate complex species. Thermal parameters have been evaluated for each step of the decomposition. The probable mechanistic paths of decomposition of these complexes have been proposed.

Acid hydrazides as ligands - II: Metal complexes of dicarboxylic acid (di)hydrazides

Abstract Metal complexes of succindihydrazide and those of malondihydrazide not described earlier are reported. Electronic spectra-solid and solution-of cobalt, nickel, copper and palladium complexes, and i.r. spectra of dueterated and non-deuterated complexes in the range 1600−700 cm −1 are incorporated. The ligands are bidentate and the coordination sites are the secondary amide nitrogen atoms. Application of the ‘average field’ concept places the ligands at the position of en ∼ den ∼ tren in the spectrochemical series. Other physical properties of complexes are also reported.

Preparation, Characterization and Solid State Thermal Studies of Cadmium(II) Squarate Complexes ofhane-1,2-diamine and its Derivatives

Abstract[CdL3]C4O4 [L=ethane-1,2-diamine (en)], [CdL2(H2O)2]C4O4 [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten), N-propylethane-1,2-diamine (pren), propane-1,2-diamine (pn) and N-methylpropane-1,2-diamine (ibn)] and [CdL2(C4O4)] [L=N-isopropylethane-1,2-diamine (ipren)] have been synthesized by the addition of the respective diamine to finely powdered CdC4O4×2H2O and their thermal studies have been carried out in the solid state. [Cd(en)3]C4O4 upon heating loses two molecules of diamine in two overlapping steps yielding Cd(en)C4O4 which upon further heating transforms to unidentified products. The diaquabis(diamine) species, [CdL2(H2O)2]C4O4, show thermally induced deaquation-anation reaction in the solid state and thereby produce [CdL2(C4O4)], which reverts on exposure to humid atmosphere (RH =90%) for 20–24 h. All the squarato bis(diamine) species, [CdL2(C4O4)], on pyrolysis in the solid state transform to unidentified products through the formation of intermediates, CdL1.5C4O4, (L=meen, pren and ipren), CdLC4O4 (L=meen, en, pren, ipren, pn and ibn) and CdL0.5C4O4 (L=eten, pn and ibn). However, amongst the intermediates only the mono diamine species, CdLC4O4 can be isolated in pure form and the pyrolytic process is the only way to synthesize them. The monodiamine species can be stored in a desiccator as well as in an open atmosphere and proposed to have a polymeric structure.

Thermal studies of Cd(II) hydrazine complexes in the solid state

Abstract The synthesis and characterization of CdL n X 2 · m H 2 O, where L = N 2 H 4 ; n = 3, 2, 1.75 and 1; X = Cl − , Br − and 1 2 SO 2− 4 ; and m = 0 or 0.5, have been done and their thermal studies have been carried out using a Shimadzu DT-30 thermal analyzer. Several complexes of the type CdL n X 2 , where n = 1.25, 1, 0.66, 0.33, have been synthesized pyrolytically in the solid state from parent complexes synthesized from solution. Several varieties of [CdL 0.66 Cl 2 ] synthesized pyrolytically are indistinguishable by IR spectra but distinguishable by thermal profile. A similar phenomenon has been observed in cases of [CdL 0.33 Cl 2 ], [CdL 0.66 Br 2 ], [CdL 0.33 Br 2 ], [CdL 0.66 SO 4 ] and [CdL 0.33 SO 4 ]. The unique feature of freshly prepared complexes synthesized from solution is that they undergo either internal rearrangement or lose one molecule of ligand at ambient temperature while keeping them in a desiccator for about 1 month. All these complexes are white in color and show bridging character of hydrazine evident from the IR spectral band. The decomposition reactions appear endothermic as well as exothermic.

STRUCTURAL EXPLORATION OF HYDROXO BRIDGED TRIAMINE COMPLEXES OF ZINC(II)

Abstract Single crystal structure of [Zn2(dpt)2(μ-OH)](ClO4)3 (dpt = bis(3-aminopropyl) amine) shows that two units of Zn(dpt) are bridged by oxygen atom of the hydroxo group. Each Zn-atom possesses distorted tetrahedral geometry. Analogous complexes [Zn2L2(μ-OH)](ClO4)3 [L = bis(3-aminopropyl) methylamine(medpt), bis(2-aminoethyl)methylamine(medien)] have been synthesised.

Thermal Studies of Copper(II) Squarate Complexes of Diamines in the Solid State

CuL2C4O4 [L=ethane-1,2-diamine (en)], CuL2C4O4⋅2H2O [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten),N-propylethane-1,2-diamine (pren), N-methyl-N’-ethylethane- 1,2-diamine (meeten) andpropane-1,2-diamine (pn)], CuL2C4O4⋅0.5H2O [L=N,N’-dimethylethane- 1,2-diamine (dmeen)], CuL2C4O4⋅4H2O [L=propane-1,2-diamine (pn)]and CuL2C4O4⋅H2O[L=2-methylpropane-1,2-diamine (ibn)] have been synthesized by the addition of respective diamine to finely powdered CuC4O4⋅2H2O and their thermal studies have been carried out in the solid state. Cu(en)2C4O4 upon heating loses one molecule of diamine with shar pcolour change yielding Cu(en)C4O4 which upon further heating transforms to unidentified products. All aquated-bis-diamine species [CuL2C4O4⋅2H2O, CuL2C4O4⋅0.5H2O and CuL2C4O4⋅H2O] upon heating undergo deaquation–anation reaction in the solid state showing thermochromism and transform to CuL2C4O4, which revert on exposure to humid atmosphere (RH ∼90%). All the squarato bis-diamine species, CuL2C4O4, on further heating transform to unidentified products through the formation of CuLC4O4 as intermediates. The mono diamine species, have been isolated pyrolytically in the solid state and can be stored in a desiccator as well as in open atmosphere. They are proposed to be polymeric.

Thermal decomposition of compounds containing the hydrazinium cation as a ligand

Abstract A thermal investigation of M(N 2 H 5 ) 2 (SO 4 ) 2 , where M = Mn(II) or Co(II), has been carried out. On heating, the complexes become MSO 4 via an intermediate compound, M(N 2 H 4 ) 0·5 (HSO 4 )(SO 4 ) 0·5 . The intermediate compound has been isolated and characterised by elemental analyses, IR spectra, diffuse reflectance spectra, magnetic and conductance data. The intermediate compound seems to possess pseudo-tetrahedral coordination where one SO 4 group is tetradentate and bonded with four different metal ions which are surrounded by HSO 4 groups and hydrazines bridging two metal ions. The X-ray powder diffraction pattern of the intermediate derived from the cobalt(II) complex has been obtained and the d -values are reported. Activation energies ( E * ) and enthalpy changes (Δ H ) for each decomposition step have also been calculated. The probable mechanisms of decompositions are discussed.

Thermal Studies of Nickel(II) Squarate Complexes of Triamines in the Solid State

Abstract[NiL2]C4O4·nH2O [where n=2 when L=diethylenetriamine(dien) and N-(3-aminopropyl)-1,3-propanediamine (dpt); n=3 when L=N-(2-aminoethyl)-1,3-propanediamine (aepn); n=0 when L=N2-methyldiethylenetriamine (medien)] and Ni(tmdien)C4O4·2H2O (where tmdien=1,4,7 trimethyl-diethylenetriamine) have been synthesised and investigated thermally in the solid state. Ni(dpt)C4O4·H2O has also been synthesised pyrolytically in the solid state from the corresponding bis complex. All the complexes possess octahedral geometry. The squarate anion takes part in coordination only in monotriamine species. [Ni(medien)2]C4O4 upon heating undergoes phase transition (270–285°C; ΔH=4.9 kJ mol−1) accompanied by colour change pink to grey. Thermal stability decreases with increase in chain length of the triamines.