S. Shanmuga Sundara Raj

Syntheses, crystal structures and properties of the novel Co(II) and Ni(II) complexes with 4-(p-methylphenyl)-3,5-bis(pyridin-2-yl)-1,2,4-triazole

Abstract The chelating properties of 4-(p-methylphenyl)-3,5-bis(pyridin-2-yl)-1,2,4-triazole (MBPT) were investigated through the study of the crystal structures of [Co(MBPT)2(H2O)2](ClO4)2·4H2O (1), [Ni(MBPT)2(H2O)2](ClO4)2 (2) and MBPT and the analysis of IR and ESIMS spectra. The metal atom is in a distorted octahedral environment. Two bidentate chelating ligands (MBPT) coordinate to metal center equatorially and two water molecules coordinate axially. Each MBPT coordinates via one triazole nitrogen atom and one pyridine nitrogen atom. The magnetic measurements show that the complexes are high-spin species in the 75–300 K range.

Synthesis of copper(II) and nickel(II) complexes using compartmental ligands: X-ray, electrochemical and magnetic studies

Abstract Acyclic dicompartmental ligands suitable for the complexation of transition-metal ions which can form mononuclear, homo- or heterodinuclear complexes have been synthesised. The mononuclear complexes ML1 (M=Cu, Ni) where L1=N,N′-bis[2-hydroxy-3-(morpholino-1-ylmethyl)-5-methylbenzyl]alkyldiimine (alkyl=ethylene, L1a; propylene, L1b; butylene, L1c; triethylenetetraamine, L1d); ML2 (M=Cu, Ni) where L2=N,N′-bis[2-hydroxy-3-(morpholino-1-ylmethyl)-5-methylbenzyl]alkyldiamine (alkyl=ethylene, L2a; propylene, L2b); and ML3 (M=Cu, Ni) where L3=N,N′-bis[2-hydroxy-3-(morpholino-1-ylmethyl)-5-bromobenzyl]alkyldiimine (alkyl=ethylene, L3a; propylene, L3b; butylene, L3c) have been synthesised and characterised by C, H, N analysis, IR, electronic and ESR spectra. The complexes CuH2L1a (1), CuH2L2a (4), NiH2L1a (9) and NiH2L1d (12) have been analysed by X-ray crystallography. Complexes 1 and 4 have square pyramidal geometry. The coordination geometry around the metal ion in complex 9 is square planar and in complex 12 it is octahedral. Electrochemical studies of the complexes show a single quasi-reversible electron transfer process at the negative potential region. For copper complexes (1–8) Epc=−1.10 to −0.70 V, for nickel complexes (9–12) Epc=−1.0 to −0.85 V. Copper complexes show a magnetic moment value of μeff=1.70–1.75 BM. The square planar nickel complexes are diamagnetic whereas the nickel complex (12) with octahedral structure has a magnetic moment value of 3.12 BM.

Synthesis and crystal structure of a chiral two-dimensional metal-organic coordination polymer: (S-(-)-lactate) (isonicotinato)zinc(II)

The synthesis and X-ray characterization of the first example of an L-lactic acid two-dimensional metal coordination polymer with an additional bridging ligand, (S-(-)-lactate)(isonicotinato)zinc(II), (S-µ-2-hydroxypropanoinato)zinc(II), 1 is reported. It crystallizes in the acentric orthorhombic space group P212121 and displays powder SHG efficiencies ca. 1.2 times that of urea.

Triboluminescence and crystal structures of non-ionic europium complexes

The triboluminescence of three non-ionic europium complexes, Eu(TTA)3·bipy (1), Eu(TTA)3·dia (2) and Eu(DBM)3·dmbp·H2O (3) (TTA = 2-thenoyltrifluoroacetonate, DBM = dibenzoylmethanate, bipy = 2,2′-bipyridine, dia = 4,5-diazafluoren-9-one, dmbp = 4,4′-dimethyl-2,2′-bipyridinate), was observed. Structure determinations of 1 and 3 were carried out. The triboluminescence maxima of 1 and 2 are similar to those of their photoluminescence. The disorder of the thienyl ring and CF3 groups in 1 and the disorder of water in the packing of 3 may be responsible for their triboluminescent activity.

Dinuclear copper(II) complexes with different bridging connectors

Abstract One novel triply-bridged dicopper(II) complex formulated as [Cu2(dpa)2(μ-Cl)(μ-OH)(μ-HCOO)]·(ClO4) 1 and two terephthalate anions bridged 2,2′-bipyridine (2,2′-bpy) dicopper(II) complexes with formulae of [Cu2(2,2′-bpy)4(μ-terephthalate)]·(NO3)2 2 and [Cu2(2,2′-bpy)4(μ-terephthalate)]·(terephthalate) 3, respectively, have been synthesized and characterized by infrared and electrospray mass spectra as well as X-ray single-crystal determination. In addition, thermal properties of all compounds have been studied.

Synthesis of mononuclear nickel(II) and copper(II) complexes using compartmental ligands: X-ray and electrochemical studies

Abstract A series of mononuclear complexes ML 1 (M=Ni, Cu) where L 1 = N , N ′-bis[2-hydroxy-3-(piperidin-1-ylmethyl)-5-methylbenzyl]alkyldiimine (alkyl=ethylene L 1a , propylene L 1b , butylene L 1c ) and ML 2 (M=Ni, Cu) where L 2 = N , N ′-bis[2-hydroxy-3-(piperidin-1-ylmethyl)-5-bromobenzyl]alkyldiimine (alkyl=ethylene L 2a , propylene L 2b , butylene L 2c ) have been synthesized and characterized by C, H, N analysis, IR, electronic and ESR spectra. The crystal structures of the complexes NiH 2 L 1a ( 1 ) and CuH 2 L 1a ( 6 ) were determined and the geometry around the metal ion is square planar. Electrochemical studies of the complexes show a quasi-reversible single redox wave at negative potential in the range 0 to −1.3 V. For nickel complexes ( 1 – 5 ) E pc =−1.0 to −0.80 V and for copper complexes ( 6 – 9 ) E pc =−0.90 to −0.72 V. The ESR spectra of nickel complexes are inactive due to square planar nature of the complexes whereas copper complexes show an ESR spectrum characteristic of square planar complex with nuclear hyperfine spin 3/2. Copper complexes show a normal magnetic moment value of μ eff =1.70–1.75 B.M. which is close to the spin-only value of 1.73 B.M.

Triboluminescence and crystal structures of europium(III) complexes

Abstract The triboluminescence of four europium complexes [Eu(TTA) 4 ]Y (TTA: 2-thenoyltrifluoroacetone; complex 1 , Y1: 1,2-dimethylpyridinium; complex 2 , Y2: 1,2,6-trimethylpyridinium; complex 3 , Y3: N -methylisoquinolium; complex 4 , Y4: 4-aminopyridinium) was observed. The triboluminescent spectra of 1 – 4 and the crystal structures of 1 , 3 and 4 were determined. The triboluminescence maxima are all similar to those of their photoluminescence, indicating identical emitting species. The triboluminescent activity of 1 may be correlated with its non-centrosymmetric space group. The disorder of the thienyl rings and CF 3 groups in centrosymmetric 3 and 4 may be responsible for their triboluminescent activities.

trans–cis S-Benzyl dithiocarbazate

In the crystal structure of the title compound, C(8)H(10)N(2)S(2), the molecules are linked by N-H.S hydrogen bonds between the imino group and the thione-S atoms to form a chain along the b axis. The dithiocarbazate moiety is rotated by 85.8 (2) degrees with respect to the phenyl ring.

Synthesis and crystal structure of 4-(p-methoxyphenyl)-3, 5-bis(4-pyridyl)-1,2,4-triazole

The 4-(p-methoxyphenyl)-3,5-bis(4-pyridyl)-1,2,4-triazole has been synthesized and its crystal structure has been determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P21/n, with a = 12.5832(6) Å, b = 7.0512(5) Å, c = 18.4669(12) Å, β = 96.826(1)°, and Dcalc = 1.345 g cm−1 for Z = 4. In the structure, two pyridyl rings, phenyl ring, and triazole ring do not share a common plane. The most favored orientation of the pyridyl rings in the crystal is that their planes are inclined toward opposite directions with respect to the triazole ring.

[4-(4-Methylphenyl)-3,5-bis(2-pyridyl)-4H-1,2,4-triazole]bis(triphenylphosphine)silver(I) perchlorate

The coordination geometry of silver(I) in the title compound, [Ag(C 19 H 15 N 5 )(C 18 H 15 P) 2 ]ClO 4 , is distorted tetrahedral. The pyridyl groups, the substituted benzene ring and the 1,2,4-triazole moiety do not share a common plane. The perchlorate ion is highly disordered and is involved in C-H...O hydrogen bonding.