Synthesis,crystal structure and magnetic characterization of a dinuclear Mn(II) complex with double end-on azide ligands

A new dinuclear manganese(II) complex [MnL(N₃)₂]₂ · 2CH₃OH 1 has been synthesized and characterized crystallographically and magnetically. L is a tridentate Schiff base ligand which is derived from the reaction of pyridine-2-carbaldehyde and 2-aminoethylbenzimidazole. In the complex 1, each Mn(II) ion is coordinated by one L, one terminal azide ligand and symmetrical double end-on bridging azide ligands. The intermolecular hydrogen bonds extend the structure into a two-dimensional layer. Magnetic determination of 1 indicates that ferromagnetic exchange interaction between the two manganese(II) ions exist in this complex through the double end-on azide bridges.     

Synthesis,crystal structure and bioactivity of a novel linear trinuclear nickel(II) complex

A novel linear trinuclear nickel(II) complex, [Ni₃(H₂O)₂(DMA)₂(acbshz)₂]·2DMF (DMA = dimethylamine; acbshz = N-acryloyl-5-bromosalicylhydrazide), has been prepared by self-assembly approach. The three nickel atoms arrange in a strictly linear structure, adjacent molecules are linked by intermolecular H bonds to form a 2D infinite wave-like structure. Antibacterial screening data indicate the formation of the trinuclear complex reduced the antimicrobial activity of the ligand.     

A new NiCuCu Ni complex containing doubly end-on azido bridged dicopper(II) and macrocyclic nickel(II) complex ancillary ligands: Synthesis, structure and magnetism

[Cu₂(NiL)₂(N₃)₄] was synthesized by combining “complex as ligand” approach and “pure bridging ligand” approach (H₂L = dimethyl 5,6,7,8,15,16-hexahydro-15-methyl-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate). The two Cu^II ions are bridged by two end-on azido ligands. ππ and oxamido–carbonyl interactions link the molecules into 1D supramolecular chains. Ferromagnetic interactions exist between the two Cu^II ions.     

Synthesis, characterization and crystal structure of a novel thiocyanate–ruthenium(II) complex

The cis-[Ru(dppb)(Me-bipy)(NCS)₂], dppb = 1,4-bis (diphenylphosphino)butane, Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, and NCS = thiocyanate, was synthesized and characterized by spectroscopic and electrochemical techniques and its structure was determined by crystal X-ray analysis. The crystal structure reveals that the coordination geometry around the Ru(II) center is distorted octahedron where two molecules of thiocyanate are bonded to the ruthenium through nitrogen atom in cis orientation. The half-wave formal potential value E_1/2 = 0.8 V (versus Ag/AgCl) observed is considerable higher than that for the cis-[RuCl₂(dppb)(Me-bipy)] complex, E_1/2 = 0.6 V (versus Ag/AgCl), well illustrating the strong π-acceptor effect the NCS ligand toward the backbonding interaction with the Ru(II) metal center. The MLCT absorption bands of the thiocyanate complex present a higher molar absorptivity (about 12%) compared with the cis-[RuCl₂(dppb)(Me-bipy)] complex, in the same experimental conditions. These properties make the complex potentially promising for the photosensitization process.     

Synthesis,structure and catalytic activities for hydrogen transfer reaction of the carbonyl ruthenium(II) complex containing polypyridine and phosphine ligands

The synthesis and characterization of new ruthenium(II) carbonyl complexes containing polypyridine and triphenylphosphine ligands is reported. Crystallographic information obtained for the trans-PPh₃-[Ru(biq)(PPh₃)₂(CO)]Cl₂ complex (biq = 2,2’-biquinoline) reveals five-coordination on the metal. The complexes were studied as catalysts in hydrogen transfer reactions in basic solution. Turnover frequencies in the 2250-817 h^-1 range were determined in 1 hour of reaction with a substrate/catalysts ratio of 830.     

Bimetallic cis-dioxomolybdenum(VI) complex containing hydrazone ligand: Syntheses,crystal structure and catalytic studies

Bimetallic molybdenum(VI) complex [(MoO₂)₂(slsch)(H₂O)₂] containing dihydrazone ligand was synthesized by reaction of ligand with MoO₂(acac)₂ in 1:2 M ratio in methanol. The bimetallic complex obtained was characterized by various spectroscopic studies. The structure of complex was assigned using Single Crystal X-ray Crystallography and DFT method. We have also explored the catalytic behavior of complex for oxidation of primary benzylic, aliphatic, allylic, and propargylic alcohols.     

Synthesis, structure and magnetic properties of a novel lead(II) complex containing nitronyl nitroxide radicals

The lead(II) complex with nitronyl nitroxide, [Pb(NIT2Py)₂(NO₃)₂] [NIT2Py = 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], has been prepared and characterized by magnetic and single-crystal X-ray diffraction studies. In the complex, the lead(II) ion is coordinated with two bidentate nitronyl nitroxide and two nitrate anions. The lead(II) ion shows seven-coordinate geometry. Magnetic susceptibility data for the title complex has been measured in the range 5–300 K. There are antiferromagnetic interaction between the coordinated nitronyl nitroxides (J = −19.35 cm⁻¹) and intermolecular ferromagnetic interactions. Thus, we observe the sixth periodic IVA group metal element Pb(II) ion providing an effective pathway for the magnetic exchange interaction between nitronyl nitroxide radicals.     

Synthesis,structure, and stability studies of dimeric gadolinium(III) complexes containing cyclic polyaminopolycarboxylic bisamide ligands

Dimeric gadolinium complexes containing polyaminopolycarboxylate bisamide ligands have been synthesized and characterized. They contain one coordinated water molecule in the solid state and in aqueous medium. Their thermodynamic stability is found to be high and suitable for MRI investigation.     

Synthesis, crystal structure and luminescent properties of a thiocyanato bridged two-dimensional heteronuclear polymeric complex of cadmium(II) and copper(II)

A novel heteronuclear polymeric complex Cd(SCN)₃Cu(en)₂NO₃ (1) (en = ethylenediamine) has been synthesized and structurally characterized. The Cd(II) atom is surrounded by three S atoms and three N atoms from four 1,3-μ-SCN⁻ and two 1,1,3-μ-SCN⁻ to attain a distorted octahedral coordination geometry. Six Cd(II) centers are linked by twelve thiocyanato bridges to form hexagonal metallocyclic unit [Cd₆(SCN)₁₂] and extend a 2D network. Moreover, a 1,1,3-μ-SCN⁻ links two cadmium and one copper metal atoms. The luminescent properties of 1 in the solid state were investigated.     

Synthesis,crystal structure and photophysical properties of a novel Pt(II) complex with multi-functionalized cyclometalating ligand

A novel Pt(II) complex [(L)PtCl] (HL = 4-{p-[N-(4-(9-carbazole))butyl-N-phenyl] aniline}-6-phenyl-2,2′-bipyridine) has been synthesized and verified by ¹H NMR, elemental analysis and X-ray crystallography. The crystal (C₄₄H₃₅N₄ClPt, M_r = 850.30) belongs to monoclinic system, space group P2(1)/c, with a = 21.864(6), b = 9.306(3), c = 17.240(5) Å, β = 96.483(6)°, Z = 4, V = 3485.3(16) ų, D_C = 1.620 g/cm³, μ(Mo-Kα) = 4.141 mm^? 1, F(000) = 1688, R₁ = 0.0591, wR₂ = 0.0976. The coordinate geometry of the Pt atom is a distorted square planar configuration. The complex molecules are stacked by a weak π–π interaction in a head-to-tail fashion along the b axis to form 1D chain and the alternating 1D chains are packed to form the 2D lamellar system. The complex shows an intense metal-to-ligand charge transfer (¹MLCT) (dπ(Pt) → π*(L)) transitions (ε ～ 2 × 10⁴ dm³ mol^? 1 cm^? 1) at 448 nm in the UV–Vis absorption spectrum and a strong phosphorescence at 592 nm in CH₂Cl₂ solution at room temperature. An intramolecular energy transfer process from the carbazole unit to the arylamine-modified [(C^N^N)PtCl] emissive center exists in the complex.     

Synthesis and crystal structure of a mononuclear Ni(II) complex with tetraazadiphenol macrocycle bearing cyclohexanes

The mononuclear tetraazadiphenol macrocyclic nickel(II) complex [Ni(H₂[20]-DCHDC)](ClO₄)₂ (II) {H₂[20]-DCHDC = 14,29-dimethyl-3,10,18,25-tetraazapentacyclo-[25,3,1,0^4,9,1^12,16,0^19,24] ditriacontane-2,10,12,14,16(32),17,27(31),28,30-decane-31,32-diol} has been synthesized by self-assembly and characterized by elemental analysis, conductance, IR and FAB-MS spectrum, and single crystal X-ray diffraction. In the mononuclear complex, the Ni(II) ion is coordinated with a square planar conformation by two phenolate groups and two iminic sites on one side of the macrocycle. The bond angles of O–Ni–O {85.37(19)°} and N–Ni–N {88.0(2)°} are smaller than 90°.     

An unexpected oxovanadium(IV) complex with in situ generated lactone ligand: Synthesis,crystal structure and DNA-binding property

A novel unexpected oxovanadium(IV) complex, [VO(L)(Phen)] (H₂L = 2-((2-hydroxynaphthalen-1-yl)-methyleneamino)-5-oxotetrahydrofuran-2-carboxylic acid, Phen = 1, 10-phenanthroline) (1), in which the L^2– is an unexpected in situ generated lactone Schiff base ligand from the precursor of K₂HL¹ (K₂HL¹ = potassium 2-(((2-hydroxynaphthalen-1-yl)methylene)amino)pentanedioate), has been synthesized and structurally characterized. The DNA binding properties of 1 with calf thymus DNA (CT-DNA) have been investigated by fluorescence and circular dichroism (CD) spectra, results indicate that 1 can bind to CT-DNA via an intercalative mode.     

Ru(II) and Zn(II) complexes of multicomponent ligands incorporating triazine-based tridentate ligands

Ru(II) and Zn(II) complexes of multicomponent ligands have been synthesised and characterised incorporating triazine-based coordinating motifs with pendant phenanthryl and phenyl–phenanthryl groups. At room temperature the ligands emit from intra-ligand charge-transfer (ILCT) states, the energy of which may be lowered significantly by metal–ion coordination (e.g. Zn(II)). The ILCT state is efficiently quenched in the Ru(II) complexes by energy transfer to a low-lying metal–ligand charge-transfer ³MLCT state.     

Synthesis,crystal structures and properties of two Pd(II) and Pt(II) complexes involving 3,5-diphenylpyrazole and NO2 donor ligands

A pyrazolate bridged binuclear Pd(II) complex [Pd₂(μ-dppz)₂(Hida)₂] · CH₃OH · 2H₂O (1) (dppz = 3,5-diphenylpyrazolate) with monoprotonated iminodiacetate (Hida) and a mononuclear Pt(II) complex containing Hdppz and 2,6-pyridinedicarboxylate (2,6-dipic) [Pt(Hdppz)(2,6-dipic)] · CH₃OH (2) have been synthesized and characterized by elemental analysis, ¹H NMR, ESI-MS and single crystal X-ray diffraction studies. The molecular packing for 1 shows a 2D network while that for 2 constitutes a left-handed 1D helix. Moderate luminescence property and antimicrobial activity against Bacillus subtilis have been noted for both.     

Synthesis,crystal structure and relevant antiproliferative activity against Toxoplasma gondii of a new binuclear Co(II) complex

The crystal structure of [(HPClNOL)Co(-μ-Cl₂)Co(HPClNOL)](ClO₄)₂ 1 (HPClNOL: 1-(bis-pyridin-2-ylmethyl-amino)-3-chloropropan-2-ol) revealed a distorted octahedral geometry around both Co(II) centers. The coordination plane comprised one tertiary amine, one alcohol in the protonated form and two chloride which link the two Co(II) centers, resulting in the binuclear arrangement. Two pyridine nitrogen atoms are coordinated and occupy the axial sites. Investigations in solid state and in solution (dimethylformamide) carried out by electronic spectroscopy suggest that the arrangement in the solid state changes in solution. Furthermore, ESI(+)-MS and conductivimetry studies indicated the formation of mononuclear species in solution in agreement with the lability of the chloride ligands. Complex 1 reduced the growth of Toxoplasma gondii infecting LLC-MK2 host cells. After treatment this complex reduced T. gondii growth by 55%, the ligand HPClNOL had no effect on parasite growth and sulfadiazine (SDZ), traditional terapeutic compound for this parasite, was effective only after 48 h of treatment. These results suggest the relevance of the cobalt ion on the anti-toxoplasma activity.     

Synthesis and crystal structure of a novel zinc(II) coordination polymer with mixed ferrocenyl diketone and bipyridine ligands

A novel zinc(II) coordination polymer [Zn(fca)₂(bpe)]_n·2nH₂O (bpe=1,2-bis(4-pyridyl)ethene, fca=C₅H₅FeC₅H₄C(OH)CHCOCH₃) was obtained by the reaction of Zn(OAc)₂·2H₂O with bpe and 1-ferrocenylbutane-1,3-dione (ferrocenoylacetone, Hfca) in methanol solution. X-ray structural analysis reveals that the compound contains two kinds of ligands: one is the 1,2-bis(4-pyridyl)ethene ligand, directly bridging zinc(II) centers to form a one-dimensional chain [Zn(bpe)]_n, the other is the enolized ferrocenylacetone chelating the central ion. The zinc(II) ion is in an elongated octahedral environment with four oxygen atoms from two distinct enolized ferrocenoylacetone, two nitrogen atoms of the bridging 1,2-bis(4-pyridyl)ethene ligands.     

Synthesis and crystal structure of three dimensional complex from copper(II) and 1,2,4,5-benzenetetracarboxylate

A copper(II) complex {[Cu(H₂btc) (H₂O)₃]₂(H₄btc)(C₅H₁₁N)₂ · 3H₂O}_n (1) has been synthesized and characterized structurally (H₄btc=1,2,4,5-benzenetetracarboxylic acid). Open channels were formed and can accommodate piperidine molecules. TGA data show that guest water and piperidine molecules are lost at 130 °C.     

Synthesis,crystal structure,and magnetic property of a stepped tetranuclear copper(II) complex of 3,5-diisopropylpyrazole-1-methoxide

Reaction of copper(II) chloride dihydrate in methanol with deprotonated 3,5-diisopropylpyrazole-1-methanol (dippmOH) led to the tetranuclear copper(II) complex [(dippmO)CuCl]₄ (1). The crystal structure of 1 indicates that two copper(II) ions connect via the oxygen atoms of dippmO⁻ ligands each other in which two dimeric units are formed. Furthermore, one of the coordinated oxygen atoms in a dimer is bonded to an adjacent copper(II) ion positioned other dimer, which gives rise to a stepped tetranuclear structure. 1 shows strong antiferromagnetic interactions through the oxo groups within the dimeric units (J₁ = − 239 cm^− 1) and weak antiferromagnetic couplings between the dimers (J₂ = − 15 cm^− 1).     

A unique 2D framework containing rhombic tetrameric cobalt(II) of mixed Td and Oh geometries linked by two different rigid ligands: Synthesis,crystal structure and magnetic properties

A new 2D coordination polymer with the formula [Co₄(μ₃-OH)₂(H₂nip-2H)₂(H₂nip-H)₂(bpe)₂]_n (1) (H₂nip = 5-nitro-isophthalic acid, bpe = trans-1,2-bis(4-pyridyl)ethylene), has been hydrothermally synthesized and structurally characterized. The structure of 1 is built around uncommon, rhombic {Co₄} clusters with double T_d and double O_h Co(II) geometries, which are extended into 2D network by the rigid deprotonated H₂nip and bpe bridges. Magnetic property study indicates there is weak antiferromagnetic coupling interaction between Co(II) ions, which mainly arises from the antiferromagnetic coupling interaction in the tetramer, based on the nature of the μ₃-hydroxyl group and syn–syn carboxylate-bridged modes.     

Synthesis, spectroscopic, and electrochemical properties of one novel hexanuclear Ru(II) polypyridyl complex

One novel hexapodal ligand 1,2,3,4,5,6-hexakis[(4,5-diazafluoren-9-yliminoxy)methyl]benzene (L) and corresponding Ru(II) polypyridyl complex [(bpy)₁₂(Ru^II)₆L](PF₆)₁₂ have been synthesized. Spectroscopic properties of the complex are investigated by UV–Vis absorption and fluorescence spectrometry. The complex shows metal-to-ligand charge transfer absorption at 438 nm and emission at 579 nm. Cyclic voltammetry of the complex comprises one Ru(II)-centered quasi-reversible oxidation at 1.31 V and three ligand-centered reductions.