Structure of a new trinuclear nickel(II) complex with a salen-type bisoxime ligand

A new trinuclear Ni(II) complex {[NiL(DMF)]₂(OAc)₂Ni}·2DMF (H₂L = 4,4′-dichloro-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol) is synthesized and characterized by elemental analyses, IR spectra, UV-Vis spectra and X-ray crystallography. The results show that the Ni(II) complex consists of three Ni(II) ions, two tetradentate (μ-L)^2? units, two coordinated μ-acetate ions, two coordinated DMF molecules, and two crystallization DMF molecules. All hexacoordinated Ni(II) ions of the complex have a slightly distorted octahedral geometry. The crystal packing of the Ni(II) complex reveals a notable feature of this structure: the formation of an infinite supramolecular 2D layered structure by virtue of intermolecular C-H…O hydrogen bonding.     

Synthesis,structure, and biological properties of a Co(II) complex with tridentate Schiff base ligand

A new Co(II) complex of general formula [Co(L)₂] has been synthesized from a NNO tridentate Schiff base ligand, 2-[(piperidin-2-ylmethylimino)-methyl]-phenol (L). The title complex is characterized by elemental, spectroscopic, antibacterial, and single crystal X-ray structural studies. X-Ray crystallography reveals that the complex shows a distorted octahedral geometry around the Co(II) ion. The complex was tested against several bacteria and shows good antibacterial activities against almost all of the bacteria. The interactions of the title complex with calf thymus deoxyribonucleic acid (CT-DNA) have been investigated by electronic absorption and fluorescence spectroscopy, showing that the complex interacts with CT-DNA via partial intercalation. Thermogravimetric analysis (TGA) of the complex has also been reported and the result shows that the complex is thermally stable up to 134 °C.     

Crystal structure and properties of a Cu(II) complex with the tridentate Schiff-base ligand,paeonol-(2-aminoethylpiperazine)

A new copper Schiff-base complex [Cu(C₁₅H₂₃N₃O₂)(NO₃)]NO₃ was synthesized and characterized by spectroscopic (IR), thermal (TG/DTA) and electrochemical methods. Single crystal X-ray diffraction revealed that the complex is monoclinic, space group P2(1)/c, with a = 23.549(2), b = 6.583(12), c = 12.765(15) Å, β = 102.823(2)°, V = 1929.4(5) ų, Z = 4, D _calcd = 1.601 Mg m^?3, F(000) = 964, goodness-of-fit = 1.034 and R ₁ = 0.0407. The Cu(II) is four-coordinate with distorted square planar geometry. The structure consists of isolated [Cu(C₁₅H₂₃N₃O₂)(NO₃)]⁺ and a nitrate, which are further linked to a 3D network by significant N–H ··· O, N–H ··· N hydrogen bonds and weak O ··· Cu interaction.     

Structural and spectral studies of a new copper(II) complex with a tridentate thiosemicarbazone ligand

The reaction of copper(II) chloride dihydrate with 2-hydroxy-3-methoxybenzaldehydethiosemicarbazone (HL) ligand in a 1:1 ratio forms the complex [Cu(L)(Cl)] · H₂O. The complex is characterized by spectroscopic, electrochemical, and thermal analysis. X-ray crystallographic analysis reveals that the central copper atom displays the distorted square planar geometry. The water molecule present in the lattice participates in a strong hydrogen bonding network, which leads to a 2D supramolecular arrangement.     

An unusually stable trinuclear manganese(II) complex bearing bulk carboxylic radical ligands

A trinuclear MnII cluster based on the versatile polychlorinated triphenylmethyl carboxylic radical ligand has been characterized by X-ray crystallography and magnetic measurements, representing a rare example of a MnII trinuclear linear structure with six open-shell ligands.     

The chiral helical structure of a copper(II) complex with a tridentate Schiff base ligand

In the title salt, catena‐poly[[[aquacopper(II)]‐μ‐3‐(2‐pyridylmethyleneamino)propanoato‐κ⁴N,N′,O:O′] perchlorate], {[Cu(C₉H₉N₂O₂)(H₂O)]ClO₄}_n, the monomeric unit contains a square‐based pyramidal Cu^II centre. The four basal positions are occupied by a tridentate anionic Schiff base ligand which furnishes an NNO‐donor set, with the fourth basal position being occupied by an O‐donor atom from the carboxylate group of an adjacent Schiff base ligand. The coordination sphere is completed by a water molecule at the apical position. Interestingly, each carboxylate group in the ligand forms a syn–anti‐configured bridge between two Cu^II centres, leading to left‐handed chiral helicity. The framework also exhibits O—H...O hydrogen bonds involving the water molecules and an O atom of the perchlorate anion.     

Distorted pentacoordinate copper(II) complexes containing a tridentate ligand

Summary Copper(II) complexes with a tridentate chelating ligand within the general 2N, X (X = O or S) donor class, containing abis(benzimidazolyl) donor set, were prepared and characterized. X-band e.p.r. spectra of the complexes indicateg >g and the largeg and lowA have been interpreted in terms of a distorted basal plane. Superimposed on theg component are five SHF lines withA _N = 16±2G, supporting the interaction of two nitrogen atoms with the copper nucleus. Thus, the basal plane of the complex comprises 2N atoms, with the ligand hetero atom being axially coordinated.     

Europium complex of a tridentate ligand: synthesis and spectroscopic properties

A new europium complex containing the chelate tridentate ligand and imidazole terpyridine (itpy), was synthesized. The complex was characterized by elemental analysis, mass, FT-IR and photoluminescence spectroscopic techniques. The europium complex in solution showed characteristic luminescence properties. The room temperature photoluminescence spectrum of this complex was composed of typical Eu³⁺ red emission assigned to ⁵D₀ → ⁷F₂ transition. The metal-centered red emission seemed to be promoted by the ligand-assisted energy transfer, namely antenna effect.     

Complexes of cobalt(II), nickel(II), copper(II), zinc(II) and manganese(II) with tridentate Schiff base ligand

Summary A series of metal complexes with new tridentate Schiff base derived from salicylaldehyde and furfuraldehyde with o-phenyldiamine have been prepared and characterised by physical and chemical methods. Electronic spectra, room temperature magnetic moment values, e.p.r. and X-ray photoelectron spectroscopy studies suggest an octahedral geometry for all the complexes, where low molar conductance values are in accord with their non-electrolytic nature. The thermal stability of the complexes is discussed and the ligand-to-metal bonding modes discussed.     

Synthesis and crystal structure of a copper(II) complex of the tridentate ligand di-(2-benzimidazolylmethyl)imine

A copper complex [Cu(IDB)Cl] · 0.5[CuCl₄]?·?H₂O (1) (IDB?=?di(2-benzimidazolylmethyl)imine) was synthesized and its structure was determined by X-ray single crystal diffraction. In this complex, the central copper(II) ion is four-coordinate, IDB serves as a neutral tridentate chelating ligand for the tetragonal copper ion. The cyclic voltammogram of complex 1 in CH₃CN gave two reversible redox waves (E _1/2,1?=??0.14?V and E _1/2,2?=?0.08?V versus SCE) which correspond to the Cu(II,?II)/Cu(I,?II) and Cu(II,?II)/Cu(II,?I) redox processes, respectively.     

Preparation and properties of sandwiched trinuclear palladium(II) complexes with tridentate phosphine and phosphine sulfide ligands

The central phosphino group of tripodal tetradentate tris[2-(diphenylphosphino)ethyl]phosphine (pp₃) was selectively oxidized by the reaction with diethyl disulfide to give tridentate phosphine ligand pOp₃. The terminal phosphino groups were reacted with sulfur to give pOp₃ trisulfide (pOp₃S₃). Three palladium(II) ions were sandwiched in the two pOp₃ and pOp₃S₃ ligands to form the trinuclear complexes with three trans(P) and trans(S) PdX₂ (X = Cl, Br, I) moieties, respectively. The tripodal triphosphine, 1,1,1-tris(diphenylphosphinomethyl)ethane (i-p₃), and its mono- and tri-sulfide, which have shorter carbon chains compared with pOp₃, form the mononuclear dichloro palladium(II) complexes with cis(P) and cis(S) geometries. Difference in the catalytic activity for the C–C coupling reaction was discussed in connection with the coordinated groups and geometries of the complexes.     

Monomeric Sn(II) and Ge(II) hydrides supported by a tridentate pincer-based ligand

Herein we report the syntheses of terminal Sn(II) (3) and Ge(II) (4) hydrides from the corresponding chloride precursors [{2,6-iPr(2)C(6)H(3)NCMe}(2)C(6)H(3)MCl] (M = Sn (1), Ge (2)) using [K{B(sec-Bu)(3)}H] as a hydrogenating agent. Combination of steric shielding and intramolecular N → M interactions resulted in the protection of M(II)-H bonds.     

A luminescent Pt(II) complex with a terpyridine-like ligand involving a six-membered chelate ring

The ligand 2-(8'-quinolinyl)-1,10-phenanthroline (1) was prepared in 79% yield by the Friedlander condensation of 8-amino-7-quinolinecarbaldehyde and 8-acetylquinoline. The complex [Pt(1)Cl]+ was prepared and compared with the isomeric 2-(2'-quinolinyl)-1,10-phenanthroline (2) complex. An X-ray analysis indicated that the six-membered chelate ring in the tridentate complex resulted in a relief of angle strain as well as some non-planarity in the bound ligand 1. The control system for photophysical studies is [Pt3Cl]+ where denotes 2-(2'-pyridyl)-1,10-phenanthroline. Relative to the complex of 3, in dichloromethane solution [Pt(1)Cl]+ exhibits noticeably higher energy charge-transfer absorption but slightly lower energy emission. The gap between the onset of absorption and emission is larger because the emission from [Pt(1)Cl]+ originates from a triplet excited state with substantial intra-ligand character. At room temperature in deoxygenated dichloromethane, [Pt(1)Cl]+ has an excited-state lifetime of 310 ns vs. 230 ns for [Pt(1)Cl]+. Within the series, [Pt(1)Cl]+ also exhibits the largest activation barrier for thermally induced quenching at 2730 cm(-1) in fluid dichloromethane solution. However, the barrier is only about 50% larger than that found for [Pt(1)Cl]+. There is reduced ring strain in [Pt(1)Cl]+, but inter-ligand steric interactions weaken the ligand field.     

Oxidation of alcohols using a manganese (II) complex based on a pentakis benzimidazole amide ligand

A pentakis benzimidazole based penta-amide ligand diethylenetriamine—N,N,N′,N′,N″-pentakis(2-methyl benzimidazolyl)penta-amide [GBDTPA] has been synthesized and utilized to prepare Mn (II) complexes of general composition [Mn₂(GBDTPA)X₄], where X is an exogenous anionic ligand (X = Cl⁻, NO₃⁻ and Br⁻). The oxidation of alcohols has been investigated using [Mn₂(GBDTPA)Cl₄] as the catalyst and TBHP as an alternate source of oxygen. The respective aldehydic products have been isolated and characterized by ¹H NMR.     

Magnetic ordering in a mononuclear cobalt(II) complex containing a Schiff-base pentadentate ligand

A mononuclear cobalt(II) complex CoL5, containing the pentadentate O2N3 salen-type Schiff-base ligand H2L5=N,N[prime or minute]-bis(3-tert-butyl-2-hydroxy-5-methylbenzylidenyl)-1,7-diamino-4-methyl-4-azaheptane, exhibits magnetic ordering at 4 K as proven by ac magnetic susceptibility (both in- and out-of-phase), magnetization, field-cooled magnetization and zero-field cooled magnetization measurements.     

Synthesis and studies of a trinuclear Mn(II) carboxylate complex

We report a carboxylate triangle consisting of three manganese(II) centres which is made from manganese(II) carbonate and pivalic acid. The magnetic exchange within the triangle is extremely weak, and antiferromagnetic. Several models have been used to fit the magnetic data, and the best fit uses two weak antiferromagnetic coupling constants of J(1)=-0.588 cm(-1) and J(2)=-0.855 cm(-1). Exchange interactions between the metal centres has been calculated using DFT adopting all the three possible Heisenberg models for a trinuclear system and the results are compared with experimental values. Spin density distribution is used to analyse the nature of the coupling between the metal centres. EPR spectroscopy has been used to explore the nature of the ground state. Recrystallisation of the trinuclear compound from MeCN gives a polymer, while oxidation in air leads to a known compound--an edge-sharing bitetrahedral (MnIII2MnII4) cage.     

Synthesis,crystal structure,and magnetic properties of a linear trinuclear Cu(II) complex

A new linear trinuclear Cu(II) complex, [Cu₃(NTA)₂(4,4′-bpt)₄(H₂O)₂]?·?10H₂O (H₃NTA?=?nitrilotriacetic acid, 4,4′-bpt?=?4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole) (1), was obtained from evaporation of an aqueous solution containing Cu(NO₃)₂?·?6H₂O, 4,4′-bpt, nitrilotriacetic acid (H₃NTA), and NaOH. 1 was characterized using single-crystal X-ray diffraction, IR, and elemental analysis. In the trimer, the three linear copper ions are bridged by two NTA carboxylate groups in a syn–anti conformation and connected by 4,4′-bpt to produce a 1-D array. Temperature-dependent magnetic susceptibilities reveal the presence of weak antiferromagnetic exchange between metal centers.