Dilip Kumar Dey

Synthesis and structural characterization of mixed ligand η1-2-hydroxyacetophenone complexes of cobalt(III)

Abstract A tridentate Schiff base ligand [(CH3)2NCH2CH2NC(CH3)C6H4OH)] (LH) has been synthesized from 2-hydroxyacetophenone and 2-dimethylaminoethylamine. This ligand forms the neutral complexes [Co(L)(N3){o-(CH3CO)C6H4O}] (1) and [Co(L)(SCN){o-(CH3CO)C6H4O}]·1/2H2O (2) in presence of equivalent amount of Co(II) acetate, and sodium azide for 1 and sodium thiocyanate for 2. The complexes have been characterized by spectroscopic and crystallographic methods. The coordination geometry around Co(III) in both the complexes is distorted octahedral with one tridentate ligand L, one bidentate 2-hydroxyacetophenone and one monodentate azide for 1 and thiocyanate for 2. The azide and thiocyanate ligands in the two complexes occupy different positions relative to the coordination sites of L.

Synthesis and characterization of diorganotin(IV) complexes of tetradentate Schiff bases: Crystal structure of n-Bu2Sn(Vanophen)

Abstract Diorganotin(IV) complexes of the general formula R2SnL (R=Ph, n-Bu and Me) have been prepared from diorganotin(IV) dichlorides (R2SnCl2) and tetradentate Schiff bases (H2L) containing N2O2 donor atoms in the presence of triethylamine in benzene. The Schiff bases, H2L, were derived from salicylaldehyde, 3-methoxysalicylaldehyde (o-vanillin), 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and diamines such as o-phenylenediamine and 1,3-propylenediamine. The complexes were characterized by IR, NMR (1H, 13C, 119Sn) and elemental analysis. The structure of the complex, n-Bu2Sn(Vanophen), was determined using single crystal X-ray diffraction. The tin atom has a distorted octahedral coordination, with the Vanophen ligand occupying the four equatorial positions and the n-butyl groups in the trans axial positions. Six-coordinated distorted octahedral structures have been proposed for all diorganotin(IV) complexes studied here, as they possess similar spectroscopic data.

Synthesis, spectroscopy and structure of [N-(2-carboxyphenyl)salicylideneiminato]dimethyltin(IV)

Abstract The novel dimethyltin complex with formula Me 2 Sn(2-OC 6 H 4 CHNC 6 H 4 COO), compound 1 , involving the Schiff base derived from anthranilic acid and salicylaldehyde, has been synthesized and characterized by elemental analysis, IR, 1 H-, 13 C- and 117 Sn-NMR, 119 Sn Mossbauer spectroscopy and single-crystal X-ray diffraction structure analysis. The crystals of complex 1 are monoclinic, space group P 2 1 / n , a =8.907(5), b =12.044(7), c =14.062(9) A, β =104.99(5)°, Z =4, R 1 =0.0296, wR 2 =0.08 for 1368 observed reflections. The crystal structure of 1 features centrosymmetric dimers disposed about a central Sn 2 O 2 core. The tin environment is seven-coordinate if a moderately long contact distance Sn(1)O(2a) (2.69(1) A) and a longer one Sn(1)O(3a) (3.03(1) A) are included in the coordination list. In the basic monomeric structural unit, the tin configuration can be seen as a distorted square-pyramid with the imine nitrogen atom in apical position, the N -(2-carboxyphenyl)salicylideneimine dianion coordinating a single tin atom via the phenolate oxygen atom, the imine nitrogen atom and one of the carboxylate oxygen atoms. The distortion of the square pyramid is discussed in terms of a trend to trigonal-bipyramidal geometry.

Synthesis and characterization of cyano-bridged polynuclear [Cu(dmpn)2]3[Co(CN)6]2·12H2O and trinuclear [Cu(dmpn)2]2[Co(CN)6]·ClO4·3H2O complexes

Abstract Two new heteronuclear bimetallic assemblies [Cu(dmpn)2]3[Co(CN)6]2·12H2O (1) and [Cu(dmpn)2]2[Co(CN)6]·ClO4·3H2O (2) have been prepared and crystal structures have been solved. The one-dimensional (1D) polymeric chain of 1 extended through Co–CN–Cu–NC–Co linkages. The chains are finally linked by hydrogen bonds giving rise to a unique step shaped two-dimensional (2D) network. In the crystal of 1, all the copper(II) and cobalt(III) ions have distorted octahedral geometry. In the complex 2, the copper(II) and cobalt(III) centres are linked together through cyano-bridges and both the copper(II) ions have a distorted square pyramidal geometry. Of the six CN− groups around the cobalt atom in complex 2, two coordinate to copper atoms of adjacent [Cu(dmpn)2]2+ moieties leading a non-linear trinuclear unit, of the remaining four CN− groups two are free and the other two interact through hydrogen bonds with water molecules present in each asymmetric unit. The presence of water molecules gives rise to an extensive H-bonded molecular assembly.

Studies on some di- and triorganotin(IV) derivatives of bis(1-pyrazolyl) borates and some related compounds

Abstract A number of di- and triorganotin(IV) complexes of dihydrobis(1-pyrazolyl)borate and diphenylbis(1-pyrazolyl)borate have been synthesized. The complexes derived from dihydrobis(1-pyrazolyl)borate have been converted to their dihalobis(1-pyrazolyl)borate analogues by halogenation reactions. The compounds have been characterized by elemental analysis, infrared and 1 H, 11 B and 119 Sn NMR spectra.

SYNTHESIS, SPECTROSCOPY AND STRUCTURE OF DIORGANOTIN(IV) SCHIFF BASE COMPLEXES

Three diorganotin(IV) chelates with a tetradentate Schiff base, H2Vanophen, [H2Vanophen = N,N′-1,2-phenylen-bis(3-methoxysalicylideneimine)] of the type R2Sn(Vanophen) (R = Ph: 1; R = n-Bu: 2; R = Me: 3) have been synthesized by the reaction of R2SnCl2 (R = Ph, n-Bu, Me) and H2 Vanophen in the presence of triethylamine in benzene. The complexes have been characterised by IR and NMR spectroscopy and by elemental analysis. The δ(119Sn) values for the complexes 1 - 3 are -543.0, -414.2 and -398.2 ppm respectively, indicating hexacoordinated Sn centers. These have been ascertained by X-ray crystal structure determinations of 1 and 3. The distances between tin and the two axial carbon atoms in each complex differ not significantly [2.17(1) Å in 1, and 2.100(3) and 2.115(3) Å in 3). The C-Sn-C angles for 1 and 3 are 165.9(4)° and 159.96(9)°, respectively. The solution NMR spectra (1H , 13C, 119Sn) show clearly that the solid state structures are retained in solution.

A new Cu(II) bridging-carboxylate helical chain polymer : synthesis and structural aspects

The crystal structure of a new Cu(II) carboxylato-bridged complex [Cu(L)(SCN)]n (1) [where HL = 2-N-(2′-pyridylimine)benzoic acid] forms a helical chain polymer chain. In 1, adjacent copper atoms are linked by carboxylate groups in a syn–anti conformation. The title complex was also characterised by elemental analysis, IR spectra, electronic spectra and variable temperature magnetic measurements.

Synthesis and the crystal structure of a copper(II) complex dervied from novel tridentate ligand: An unexpected one

A novel tridentate ligand C5H4NCONHCOC5H4N (HL) has been formed by Cannizzaro type reaction of pyridine-2-carboxaldehyde and NaNCO in the presence of copper metal ion and its mononuclear distorted square pyramidal complex [Cu(L)(NCO)(H2O)], 1 has been synthesised and characterised.

Simple Synthesis, Characterization and Structure of Diorganotin(IV) Complexes Containing the N-(2-Salicylidene)-N'-benzoylhydrazone Ligand

Two diorganotin(IV) complexes of general formula R2Sn[2-OC6H4CH=NDN=C(O)Ph] (R = Ph, 1; R = Me, 2) have been synthesized from the corresponding diorganotin(IV) dichloride and the Schiff base derived from salicylaldehyde and benzoyl hydrazide. The two compounds have been characterized by elemental analysis, IR and NMR (1H, 13C, 15N, 119Sn) spectra, and their structures have been confirmed by single crystal X-ray structure analysis. Crystals of complex 1 re triclinic, space group P1̄ , a = 11.1631(5), b = 13.462(2), c = 16.511(1) Å , α = 106.193(9), β = 106.379(8), γ = 94.932(8)°, Z = 4, R1 = 0.0461, wR2 = 0.0939 for 13194 unique reflections. Crystals of 2 are monoclinic, space group P21, a = 10.2073(5), b = 14.645(2), c = 10.411(3) Å, β = 92.572(9)°, Z = 4, R1 = 0.0395, wR2 = 0.0835 for 5050 unique reflections. The central tin atom of either complex adopts a distorted trigonal bipyramidal coordination with two ligand oxygen atoms in axial positions, the nitrogen atom of the ligand and two organic groups on tin occupying equatorial sites. The δ(119Sn) values for the complexes 1 and 2 are -329.2 and -150.3, respectively, thus indicating penta-coordinated tin centres.

Synthesis and Characterization of Copper(II) and Zinc(II) Complexes Containing 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone

The synthesis, structure, and physical properties of a series of mononuclear complexes viz. [Cu(L)2] 1, [CuL2(CH3O)2] 2 and [Zn(L)2] 3 (where L = 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP)) are presented. The complexes were characterized by elemental analysis, IR and electronic spectroscopy (1 and 2), magnetic measurements at room temperature (1 and 2) and thermogravimetric analysis. The structures of all the three complexes were determined by single crystal X-ray diffraction studies. The coordination geometry around complexes CuL2 (1) and ZnL2 (3) is slightly distorted square planar while the geometry around Cu(II) of [Cu(L)2(CH3O)2] (2) is distorted octahedral with four oxygen atoms of two PMBP ligand occupying the equatorial positions and two methanol molecules occupying the two axial positions.