Non-oxo vanadium(IV) complexes with acetylacetone 4-R-benzoylhydrazones

Vanadium(IV) complexes of formula [V(acRbh)₂] with acetylacetone 4-R-benzoylhydrazones (H₂acRbh, R=H, Cl, OMe and NO₂) have been synthesized and characterized by elemental analysis, IR, UV–vis, and electron paramagnetic resonance (EPR) spectroscopic measurements. All the complexes are one-electron paramagnetic and show very similar axial EPR spectra in frozen solution. In dimethylformamide, the complexes display a V(IV)?V(III) redox couple in the E _1/2 range ?0.16–?0.25?V (versus Ag/AgCl). Single crystal X-ray structures of [V(acHbh)₂] and [V(acClbh)₂] have been determined. The metal center in each complex is in a distorted trigonal prismatic N₂O₄ coordination sphere assembled by the enolate-O, the imine-N, and the iminolate-O donor acRbh^2?.     

Synthesis, DNA-binding and photocleavage studies of [Ru(phen)2(pbtp)] and [Ru(bpy)2(pbtp)] (phen = 1,10-phenanthroline; bpy = 2,2′-bipyridine; pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene)

Based on the ligand dppz (dppz = dipyrido-[3,2-a:2′,3′-c]phenazine), a new ligand pbtp (pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene) and its polypyridyl ruthenium(II) complexes [Ru(phen)₂(pbtp)]²⁺ (1) (phen = 1,10-phenanthroline and [Ru(bpy)₂(pbtp)]²⁺ (2) (bpy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, ES-MS and ¹H NMR spectroscopy. The DNA-binding of these complexes were investigated by spectroscopic methods and viscosity measurements. The experimental results indicate that both complexes 1 and 2 bind to CT-DNA in classical intercalation mode, and can enantioselectively interact with CT-DNA. It is interesting to note that the pbtp ruthenium(II) complexes, in contrast to the analogous dppz complexes, do not show fluorescent behavior when intercalated into DNA. When irradiated at 365 nm, both complexes promote the photocleavage of pBR 322 DNA.     

Effects of substituent on the DNA-binding of ruthenium(II) complexes containing asymmetric tridentate intercalative ligands

Three novel unsymmetric tridentate ligands, namely, ptmi (ptmi = 3-(1,10-phenanthroline-2-yl)-as-triazino[5,6-f]-5-methoxyisatin), pti (pti = 3-(1,10-phenanthroline-2-yl)-as-triazino-[5,6-f]isatin), ptni (ptni = 3-(1,10-phenanthroline-2-yl)-as-triazino[5,6-f]-5-nitroisatin), and their complexes [Ru(tpy)(ptmi)](ClO₄)₂ (tpy = 2,2′:6′,2″-terpyridine) (1), [Ru(tpy)(pti)](ClO₄)₂ (2), and [Ru(tpy)(ptni)](ClO₄)₂ (3) were prepared and characterized by elemental analysis, ¹H NMR, ES–MS. The electrochemical behaviors were studied by cyclic voltammetry. The DNA-binding properties of these complexes were investigated by the spectroscopic method, viscosity measurements, and thermal denaturation. Theoretical studies on these complexes were also performed with the density functional theory (DFT) method. The experimental results showed that these complexes bind to calf thymus (CT-DNA) in an intercalative mode. The order of DNA-binding affinities (A) of these complexes is A(1) < A(2) < A(3). The trend in the DNA-binding affinities of this series of complexes can be reasonably explained by the DFT calculations.     

Darstellung und Charakterisierung von Halogeno(diethyldithiocarbamato) (triethylphosphin)-nickel(II)-Komplexen

The complexes [Ni(PEt ₃)₂ dtc]X (1) and Ni(PEt ₃)Xdtc (2) (dtc=S₂CNEt ₂,X=Cl, Br, I) have been prepared. As conductivity, susceptibility, UV and IR measurements show, the cations [Ni(PEt ₃)₂ dtc]⁺ of1 and the complexes2 at ambient temperature have square-planar structure. We suppose there might exist an equilibrium for2 between square-planar and tetrahedral configuration.

     

Preparation and spectroscopic characterization of iron(II) and copper(II) complexes of a functionalized crown ether

Condensation between 4′-aminobenzo-15-crown-5- and 4-antipyrinecarboxaldehyde yielded the functionalized crown ether (L = 1,5-dimethyl-4-[(2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecin-15-ylimino)methyl]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one). A 1:1 (Na⁺:L) complex has been prepared. The reaction of Fe(II) and Cu(II) salts with L gave complexes of composition [Fe(L)Cl₂] and [Cu(L)₂Cl₂]. Heteronuclear complexes [Fe(L)Cl₂Na]ClO₄ and [Cu(L)₂Cl₂Na]ClO₄ have also been synthesized from the reactions of [Fe(L)Cl₂] and [Cu(L)₂Cl₂] with NaClO₄. The compounds have been characterized by microanalyses and spectroscopic methods.     

Thermal behaviour of platinum(II) complexes of diethyl and monoethyl 2-quinolylmethylphosphonates

Summary Thermal study of the molecular and ionic platinum(II) complexes of diethyl (2-dqmp) and monoethyl (2-Hmqmp) ester of 2­quinolylmethylphosphonic acid: dihalide adducts trans-PtL₂X₂ (L=2-dqmp, X=Cl, Br; L=2-Hmqmp, X=Cl), methylquinolinium tetrahaloplatinates [LH⁺]₂[PtX₄^2-] (L=2-dqmp, X=Cl, Br; L=2­Hmqmp, X=Cl, Br), methylquinolinium hexahalodiplatinates [LH⁺]₂[Pt₂X₆^2-](L=2-Hmqmp, X=Cl, Br) and chelate complex Pt(2­mqmp)₂·2H₂O, has been carried out using TG-DTA techniques and the infrared spectroscopic study. There are great differences in the thermal behaviour between various types of complexes, especially between the molecular and the ion-pair salt complexes.     

Synthesis and characterization of Ru(III), Rh(III), Pt(IV) and Ir(III) thiosemicarbazone complexes

Ru(III), Rh(III), Pt(IV) and Ir(III) complexes of 2-furfural thiosemicarbazone as ligand have been synthesised. These complexes have the composition [M(ligand)₂X₂]X (M = Ru(III) Rh(III) and Ir(III) X = Cl and Br) and [Pt(ligand)₂ X₂] X₂ (X = Cl, Br and 1/2SO₄). The deprotonated ligand forms the complexes of the formulae M(ligand-H)₃ and Pt(ligand-H)₃Cl. All these complexes have been characterized by elemental analysis, magnetic measurements, electronic and infrared spectral studies. All the complexes are six-coordinate octahedral.     

Ruthenium(II) and ruthenium(III) complexes derived from O,O-donor ligands

The new [Ru¹¹(PPh₃)₂L₂] complexes [L=monoanion of tropolone, benzoylacetone, or 3-hydroxy-2-pyridinone (hypy)], [RuH(PPh₃)₃L′][HL′=maltol, dibenzoylmethane or 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmhypy)] and [Ru^IIIX₂(EPh₃)₂L″] complexes (X=Cl, Br; E=As or P; L″=hypy, dmhypy) have been prepared, and characterized by spectroscopic techniques. Their redox behaviour was studied by cyclic voltammetry. Most of the complexes were found to be effective catalysts for the oxidation ofp-methoxybenzyl alcohol to the corresponding aldehyde in the presence ofN-methylmorpholine-N-oxide as co-oxidant.     

Reactions of divalent transition metal halides with 3,5-dimethyl-1-(hydroxymethyl)-pyrazole

Factors determining the complex formation reaction of copper(II), nickel(II) and cobalt(II) chloride and copper(II) bromide with 3,5-dimethyl-1-(hydroxymethyl)-pyrazole (HL) has been studied. Depending on experimental conditions, complexes with different composition were obtained: [CuCl₂(dmp)]₂ (I), [CuCl₂(dmp)₂]₂ (II), [CoCl₂(dmp)₂] (III) (dmp=3,5-dimethylpyrazole), [CuBr(L)]₂ (IV), [CoCl(L)(EtOH)]₄ (V) and [NiCl(L)(EtOH)]₄ (VI). The compounds were characterized by FTIR spectroscopy, solution conductivity and magnetic measurements. The crystal structure of [CoCl(L)(EtOH)]₄ has been determined by single crystal X-ray diffraction. The thermal decomposition of the compounds was studied and found to be continuous for all of the compounds. The desolvation mechanism of [MCl(L)(EtOH)]₄ (M=Co(II), Ni(II)) is explained on the basis of the route of complex formation of CoCl₂ with HL.     

Tricarbonylrhenium(I) and -technetium(I) complexes with bis(2-pyridyl)phenylphosphine and tris(2-pyridyl)phosphine

(NEt₄)₂[Re(CO)₃Br₃] or (NEt₄)₂[Tc(CO)₃Cl₃] react with bis(2-pyridyl)phenylphosphine (PPhpy₂) or tris(2-pyridyl)phosphine (Ppy₃) under formation of neutral tricarbonyl complexes of the composition [M(CO)₃X(L)] (M = Re, X = Br; M = Tc, X = Cl; L = PPhpy₂ or Ppy₃). In all isolated products, the ligands coordinate solely via two of their nitrogen atoms. All attempts to force a tripodal coordination of the phosphinopyridines failed. Removal of the bromo ligands from (NEt₄)₂[Re(CO)₃Br₃] by the addition of AgNO₃ in THF/water, and subsequent reaction of the resulting [Re(CO)₃(THF)₃](NO₃)with Ppy₃ yielded the complex [Re(CO)₃(NO₃)(Ppy₃-N,N′)] with a monodentate coordinated nitrato ligand. The products have been characterized spectroscopically and by X-ray structure analyses.     

Die Kristallstruktur eines polynuklearen Co(II)-Komplexes in Cs2[Co3(N3)8]

Cs₂[Co₃(N₃)₈] crystallizes monoclinic,a=1 123.8 (3),b=568.4 (2),c=1 542.6 (4) pm, =107.37 (2)°, space group P2₁/n,Z=2. The crystal structure was determined by single crystal X-ray diffraction,R _w=0.069. Coatoms are coordinated octahedrally to six azide groups and form polynuclear complexes of composition [Co₃(N₃)₈]^2–. The complex anions share edges and are connected to infinite chains running along theb-axis direction. Cesium is irregularly surrounded by azide groups.

     

Studies on the synthesis and magnetic property of binuclear oxovanadium(IV) complexes bridged by chloranilato group

Six novel oxovanadium(IV) binuclear complexes have been synthesized and characterized, namely, [(VO)₂(CA)L₂]SO₄ [L denotes 5-methyl-1,10-phenanthroline (Me-phen); 2,9-dimethyl-1,10-phenanthroline (Me₂-phen); 5-chloro-1,10-phenanthroline (Cl-phen); diaminoethane (en); 1,3-diaminopropane (pn) and 1,2-diaminopropane (ap) respectively.], where CA represents the dianion of chloranilic acid. Based on elemental analyses, molar conductivity and room temperature magnetic moment measurements, IR and electronic spectral studies, it is proposed that there complexes have CA-bridged structures and consist of two vanadium(IV) ions in a square-pyramidal environment. The complexes [(VO)₂(CA)(Me-phen)₂]SO₄ (1) and [(VO)₂(CA)(Me₂-phen)₂]SO₄ (2) were characterized by variable temperature magnetic susceptibility measurements (4～300 K) and the observed data were fitted to the modified Bleaney-Bowers equation by the least-squares method, giving the exchange integral J=-15.8 cm^?1 for 1 and J=-10.6 cm^?l for 2. This result indicates that there is a weak antiferromagnetic spin-exchange interaction between the two VO²⁺ ions within each molecule.     

配合物[Cu2(bpe)X2] n (bpe =1, 2–trans–(4–pyridyl)ethene, X=Cl, Br, I )的合成、晶体结构及热稳定性研究

以1,2-反式-二（4-吡啶基）乙烯桥连卤化铜分别得到配合物[Cu₂(bpe)Cl ₂] _n (1), [Cu₂(bpe)Br₂] _n (2) 和 [Cu₂(bpe)I₂] _n (3)。通过X-射线单晶衍射法对配合物1的结构进行了研究,晶体学数据：单斜晶系, P 2(1)/c空间群, a = 0.3788(8) nm, b = 1.5059(3) nm, c = 1.0875(2)nm, β = 96.262(4) °, V = 616.5(2)ų, Z = 2, S = 1.002,最终残差因子( I >2 σ ( I )) R ₁ = 0.0288, wR ₂ = 0.0579,对于全部数据 R ₁ = 0.0509, wR ₂ = 0.0615。元素分析及红外光谱分析表明,该类配合物为同晶化合物。另外,通过热重分析对配合物的热稳定性进行了研究。     

Ni(II) and Cu(II) complexes of new unsymmetrical N2O2 Schiff bases derived from 3-(2-aminobenzylimino)-1-phenylbutan-1-ol: synthesis,structure, antibacterial properties,and electrochemistry

Two new N₂O₂ unsymmetrical Schiff bases, H₂L¹ = 3-[({o-[(E)-(o-hydroxyphenyl)methylideneamino]phenyl}methyl)imino]-1-phenyl-1-buten-1-ol and H₂L² = 3-[({o-[(E)-(2-hydroxy-1-naphthyl)methylideneamino]phenyl}methyl)imino]-1-phenyl-1-buten-1-ol, and their copper(II) and nickel(II) complexes, [CuL¹] (1), [CuL²] (2), [NiL¹] (3), and [NiL²] (4), have been synthesized and characterized by elemental analyses and spectroscopic methods. The crystal structures of these complexes have been determined by X-ray diffraction. The coordination geometry around Cu(II) and Ni(II) centers is described as distorted square planar in all complexes with the CuN₂O₂ coordination more distorted than the Ni ones. The electrochemical studies of these complexes indicate a good correlation between the structural distortion and the redox potentials of the metal centers. The ligand and metal complexes were also screened for their in vitro antibacterial activity.     

Furopyridines and furopyridine-Ni(II) complexes

Summary The thermal decomposition of the complexes Ni(SCN)₂(fp)₄·2H2O (I), Ni(SCN)₂(mfp)₄ (II) and Ni(SCN)₂(dmfp)₃ (III) (where fp=furo[3,2-c]pyridine, mfp=2-methylfuro[3,2-c]pyridine and dmfp=2,3-dimethylfuro[3,2-c]pyridine) have been investigated in dynamic air from room temperature to 1000°C by means of TG, DTG and DTA. The chemical composition of the complexes, solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and complexometric titration. The results revealed that NiO was left as residue at the end of the thermal degradation experiments. IR data suggested that fp, mfp and dmfp were coordinated to Ni(II) through the N atom of the respective heterocyclic ring.     

Synthesis and Characterization of A Nickel(II) Complex With Bis(Benzimidazol-2-Ylmethyl) (2-Hydroxyethyl)Amine

This paper reports the synthesis, crystal structure and properties of two new mononuclear nickel(II) complexes, [NiL(phen)][ClO₄]₂(1) and [NiL(bpy)][ClO₄]₂(2), where L is bis(benzimidazol-2-ylmetheyl)(2-hydroxyethyl)amine and phen and bpy are 1,10-phenanthroline and 2,2'-bipyridine, respectively. The crystal structure of 1 ·2EtOH has been determined by single-crystal X-ray analysis. It crystallizes in the monoclinic system, space group C2/c, a= 24.279(2), b= 20.864(2), c= 17.635(1)Å, g = 121.730(2)°, Z= 8, R ₁= 0.064, wR ₂= 0.167. The Ni(II) ion in 1 ·2EtOH is coordinated to three nitrogen atoms and one oxygen atom of the ligand L and two nitrogen atoms of phen to form a distorted octahedron. Spectroscopic properties of 1 and 2 are reported.     

Thermal behaviour of new Ni(II) and Cu(II) complexes with macrocyclic ligands functionalised with 1,2,4-triazole

The investigations concerning the thermal behaviour of a series of Ni(II) and Cu(II) complexes of type [NiLCl₂]·mH₂O ((1) L:L₁, m=6; (3) L:L₂, m=4) or [CuLCl]_nCl _n ·mnH₂O ((2) L:L₁, m=6; (4) L:L₂, m=4) are presented. The ligands L(1) and L(2) have been synthesised by template condensation of 3,6-diazaoctane-1,8-diamine or 1,2-diaminoethane with formaldehyde and 2-amino-4H-1,2,4-triazole. The bonding and stereochemistry of the complexes have been characterised by IR, electronic and magnetic studies at room temperature. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against planktonic as well as biofilm embedded Gram-negative, Gram-positive and fungal strains. The thermal behaviour provided confirmation of the complexes composition as well as the number and nature of water molecules and the intervals of thermal stability.     

Spectral and thermogravimetric studies of oxohalobis(4-morpholinyldithiocarbamato)molybdenum(V) complexes

Summary Molybdenum(V) complexes [MoOX(4-Morphdtc)₂] (X=F, Cl, Br or I; 4-Morphdtc = 4-morpholinyldithiocarbamate) have been prepared from molybdenum trioxide using hydrazine hydrohalides as reducing agents. The magnetic moment values atca. 1.65 B.M. and e.p.r. studies indicated that the complexes are mononuclear and that molybdenum is in + 5 oxidation state. The i.r. spectral bands at 1500 and 960 cm^–1 suggest that the dithiocarbamate acts as a univalent bidentate ligand and the bands at 930 cm^–1 confirms the presence of a MoO³⁺ moiety in the complex. The low conductivity values for the complexes inN, N-dimethylformamide indicate that the complexes are non-ionic. The [MoOX(4-Morphdtc)₂] complexes (X=F, Cl or Br) decompose in the first step by the loss of one dithiocarbamate group, whereas in [MoOI(4-Morphdtc)₂] the iodine atom is lost in the first step. The second and third steps lead to the formation of MoS₃ and MoO₃, respectively. A six coordinate structure around Mo with an oxo, halo and two dithiocarbamate groups is proposed.     

Complexes of aminobenzylamines. part II. Complexes ofo-aminobenzylamine with palladium(II) and platinum(II)

Summary The reactions of K₂[MX₄] (M = Pd^II or Pt^II and X = Cl or Br) witho-aminobenzylamine (o-aba) have been studied in neutral aqueous solutions. Two types of complexes were isolated from these studies: [MLX₂] and [ML₂]X₂. Elemental analyses, conductivity measurements, i.r. and visible spectra suggest polymeric structures for [MLX₂] with the ligand,o-aba = L, acting as a bridge, and/or mononuclear structures for [ML₂]X₂.     

Kinetics of hydrogen peroxide decomposition in the presence of binuclear complexes of cobalt(II) with 1,4-piperazine-bis(carbothiosulfene diethylamide)

We have obtained complexes of Co(II) with 1,4-piperazine-bis(carbothiosulfene diethylamide) (L) of composition [Co₂LX₄] (X = Cl, Br, I, NCS). We discuss the characteristic features of the decomposition kinetics for H₂O₂ in the presence of these complexes and the effect of the acido ligands X on their catalytic activity. We have observed isokinetic relationships between the activation parameters and the reaction rate constants. We show that the values of the parameters α and β in the Edwards equation to a considerable extent are due to the composition of the complexes and the ratio [H₂O₂]₀/[Cat]₀.