Synthesis, spectral characterization and crystal structure of copper(II) complexes of 2-benzoylpyridine-N(4)-phenylsemicarbazone

An interesting series of nine new copper(II) complexes [Cu₂L₂(OAc)₂]·H₂O (1), [CuLNCS]·½H₂O (2), [CuLNO₃]·½H₂O (3), [Cu(HL)Cl₂]·H₂O (4), [Cu₂(HL)₂(SO₄)₂]·4H₂O (5), [CuLClO₄]·½H₂O (6), [CuLBr]·2H₂O (7), [CuL₂]·H₂O (8) and [CuLN₃]·CH₃OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the d_x²-y² orbital. The structure of the compound, [Cu₂L₂(OAc)₂] (1a) has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space group P2₁/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane, an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric dimeric structure.     

Versatile binding properties of a di-2-pyridyl ketone nicotinoylhydrazone ligand: crystal structure of a Cu(II) complex

Six new copper complexes of di-2-pyridyl ketone nicotinoylhydrazone (HDKN) have been synthesized. The complexes have been characterized by a variety of spectroscopic techniques and the structure of [Cu(DKN)(2)]·H(2)O has been determined by single crystal X-ray diffraction. The compound [Cu(DKN)(2)]·H(2)O crystallized in the monoclinic space group P2(1) and has a distorted octahedral geometry. The IR spectra revealed the presence of variable modes of chelation for the investigated ligand. The EPR spectra of compounds [Cu(2)(DKN)(2)(μ-N(3))(2)] and [Cu(2)(DKN)(2)(μ-NCS)(2)] in polycrystalline state suggest a dimeric structure as they exhibited a half field signal, which indicate the presence of a weak interaction between two Cu(II) ions in these complexes.     

Instrumentation for beam-foil spectroscopic studies in the UV-visible region

A facility for carrying out beam-foil spectroscopic studies in the UV and visible region using the 400 kV electrostatic ion accelerator at Tata Institute of Fundamental Research, Bombay is described.     

Studies on travancore monazite

Optimum conditions for the removal of phosphatic content in monazite sand by sintering with sodium carbonate are described in the previous papers in the series.? Results of investigation by D.T.A. and X-ray diffraction of the solid-solid reaction between monazite sand and sodium carbonate are now given. The D.T.A. curve shows that it is a slow exothermic reaction. X-ray diffraction patterns, besides confirming the constituents in the sintered product identified chemically, show the presence of a new phase.     

Spectral and structural studies of nickel(II) complexes of salicylaldehyde 3-azacyclothiosemicarbazones

Mononuclear nickel(II) complexes with two ONS donor thiosemicarbazone ligands {salicylaldehyde 3-hexamethyleneiminyl thiosemicarbazone [H₂L¹] and salicylaldehyde 3-tetramethyleneiminyl thiosemicarbazone [H₂L²]} have been prepared and physico-chemically characterized. IR and electronic spectra of the complexes have been obtained. The thiosemicarbazones bind to the metal as dianionic ONS donor ligands in all the complexes except in [Ni(HL¹)₂] (1). In compound 1, the ligand is coordinated as a monoanionic (HL⁻) one. The magnetic susceptibility measurements indicate that all the complexes are mononuclear and are diamagnetic. The complexes were given the formulae [Ni(HL¹)₂] (1), [NiL¹py] (2), [NiL¹α-pic] (3), [NiL¹γ-pic] · H₂O (4), [NiL²py] (5) and [NiL²γ-pic] (6). The structures of compounds 2 and 3 have been solved by single crystal X-ray crystallography and were found to be distorted square planar in geometry with coordination of azomethine nitrogen, thiolato sulfur, phenolato oxygen and pyridyl nitrogen atoms.     

[Di‐2‐pyridyl ketone N4,N4‐(butane‐1,4‐di­yl)­thio­semi­carbazonato‐κ3N,N′,S]­di­oxo­vanadium(V)

The V^V atom in the title complex, [V(C₁₆H₁₆N₅S)O₂], is five‐coordinate in a highly distorted square‐pyramidal geometry, with the pyridyl N, the azomethine N and the thiol­ate S atoms of the di‐2‐pyridyl ketone N⁴,N⁴‐(butane‐1,4‐di­yl)­thio­semi­carbazone ligand and one oxo ligand occupying the basal coordination positions, while the second oxo ligand occupies the apical position. The mol­ecules are inter­connected by weak inter­molecular inter­actions, mainly of the C—H⋯O type, involving the oxo atoms.