Tridentate Schiff base complexes of ruthenium(III) containing ONS/ONO donor atoms and their biocidal activities

New ruthenium(III) complexes of the [RuY(LL)(E)₂] type (Y = Cl or Br; LL = tridentate Schiff bases; E = PPh₃ or AsPh₃) have been synthesised by reacting [RuX₃(EPh₃)₃] (X = Cl, E = P; X = Cl or Br, E = As) or [RuBr₃(EPh₃)₂(MeOH)] with Schiff bases having the donor groups (O, N, X) viz., salicylaldehydethiosemicarbazone (X = S), salicylaldehydesemicarbazone (X = O), o-hydroxyacetophenonethiosemicarbazone (X = S) and o-hydroxyacetophenonesemicarbazone (X = O). The new complexes were characterised by elemental analysis, spectral (i.r., electronic spectra, e.p.r.), magnetic moment and cyclic voltammetry data. Biocidal activity studies were also carried out for the new complexes.     

Cobalt(III) complexes with aminothiolates

Summary This article describes some complexes of cobalt(III) with -mercaptopropylamine,N, N-dimethyl--mercaptopropylamme andN,N-dimethyl--mercaptoethylamine. The compounds are of stoichiometry [Co(ligand)₃], [Co₃(ligand)₆]_X (X=Cl or Br) and [Co(ligand)₃]X₃ (X=Cl or ClO₄). -Mercaptopropylamine yields both chelated and non-chelated compounds while theN,N-dimethyl derivatives yield only non-chelated complexes. This behaviour contrasts with the results obtained with nickel(II).     

Porous Solids of Divalent Metal Complexes Assembled Through Hydrogen Bonding and π–π Stacking Interactions

The compound N, N-di(6-methyl-2-pyridyl)formamidine (HDMepyF) has been exploited in preparation of porous materials of divalent metal complexes of the formulae M(HDMepyF)₂(NO₃)₂ (M=Cd, 1; Co, 2; Ni, 3) and M(HDMepyF)₂X₂ (M=Mn, X=Cl, 4; M=Mn, X=Br, 5; M=Ni, X=Cl, 6; M=Ni, X=Br, 7). Their structures have been determined by X-ray crystallography. Each metal center of these complexes is approximately octahedrally coordinated by four nitrogen and two halogen or oxygen donor atoms. Complexes 1– 5 and 7 self-assemble through similar hydrogen bonding motifs which involve the C–HsX (X=Cl, Br or O) hydrogen bondings and – stacking interactions between the HDMepyF ligand and the X atoms to form porous structures.     

Substitutions of organopalladium(II) species with benzimidazole derivatives

The [Pd(cod)(cotl)]ClO₄ complex (cod = cycloocta-1,5-diene; cotl = cyclooctenyl, C₁₈H₁₃ ^–) undergoes substitutions with new Schiff base ligands containing benzimidazole L [L = 2-(2-N-n-propylidenephenyl)benzimidazole (L¹); 2-(2-N-i-propylidenephenyl)benzimidazole (L²); 2-(2-N-n-butylidenephenyl)benzimidazole (L³); 2-(2-N-i-butylidenephenyl)benzimidazole (L⁴)]. Facile displacement of cod by L occurs to produce complexes of the type [Pd(cotl)L]ClO₄· nMe₂CO (n= 0; L = L¹, L² or L³; n= 2, L = L⁴). Dihalobridge complexes of the type [Pd(cotl)X]₂(X = Cl or Br) undergo halogen-bridge cleavage with L¹–L⁴ to give mononuclear complexes of the type Pd(cotl)LX · nH₂O (n= 2, X = Cl, L = L¹; n= 0, X = Br, L = L¹; n= 0, X = Cl, L = L²; n= 0, X = Cl or Br, L = L³; n= 0, X = Cl, L = L⁴; n= 2, X = Br, L = L⁴) and a binuclear complex [Pd(cotl)Br]₂L². The complexes were characterised by physical properties, i.r., ¹H- and ¹³C-n.m.r. spectral techniques and by mass spectra. Probable structures have been proposed.     

Metal complexes of sulfur-nitrogen chelating agents. Part 12. The chemistry of nickel(II), palladium(II), cobalt(II) and copper(II) complexes of N2S2 and N3S2 donor systems

Summary Nickel(II), palladium(II), cobalt(II) and copper(II) complexes of the ligandN,N-1,2-propane-bis(methyl 2-amino-cyclopent-1-ene-dithiocarboxylate) (H₂L¹),N,N-1,3-propane-bis(methyl 2-aminocyclopent-1-ene-dithiocarboxylate) (H₂L²) andN,N-[bis(methyl 2-aminocyclopent-1-ene-dithiocarboxylate)] diethylenetriamine (H₂L³) have been synthesised. Both H₂L¹ and H₂L² form complexes of the type ML, and all but the copper(II) complexes, are square planar. In the copper(II) complexes tetrahedral distortion is significantly more with CuL². From H₂L³ square planar complexes of the type [M(HL³)X] (M=Ni, X=Cl, Br, I or SCN; M=Pd, X=Cl or Br) have been obtained in which the donor unit involved is N₂SX. The composition of the cobalt(II) and copper(II) complexes is [M(H₂L³)X₂] (X=Cl or Br) which contain the chromophore [MN₃X₂].     

Synthesis and characterization of cobalt(II) and iron(III) complexes with the Schiff bases:N-(p-methylbenzylidene)-2-aminobenzimidazole andN-(benzylidene)-2-(2′-aminophenyl)-benzimidazole

Summary Reactions of CoX₂ (X=Cl, Br or NCS) and FeCl₃ with the Schiff bases:N-(p-methylbenzylidene)-2-aminobenzimidazole (pmbabi) andN-(benzylidene)-2-(2-aminophenyl) benzimidazole (bapbi) yield complexes of general formula CoL₂X₂ [except for Co(bapbi)(NCS)₂] and FeLCl₃. All complexes have been characterized by elemental analyses, i.r. spectroscopy conductivity and magnetic measurements at different temperatures; solid state and solution electronic spectra are reported for cobalt(II) complexes. The results show that the latter are pseudotetrahedral, the ligand acting as monodentate, except for Co(bapbi) (NCS)₂. On the other hand, the iron compounds probably contain pentacoordinated metal.     

The coordination chemistry ofN,N′-ethylenebis(2-acetylpyridine imine) andN,N′-ethylenebis(2-benzoylpyridine imine); two potentially tetradentate ligands containing four nitrogen atoms

Summary New complexes of the general formulae [ML_A(H₂O)₂]-Cl₂ (M=Ni or Cu), [ML_AX₂] (M=Co or Cu; X=Cl or Br), [NiL_ABr₂]·H₂O, [ML_A] [MCl₄] (M=Pd or Pt), [NiL_B(H₂O)₂]Cl₂·2H₂O, [ML_BCl₂] (M=Co, Ni, Cu, Pd or Pt; X=Cl or Br) and [ML_B] [MCl₄] (M=Pd or Pt), where L_A=N,N-ethylenebis(2-acetylpyridine imine) and L_B=N, N-ethylenebis(2-benzoylpyridine imine), have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, t.g./d.t.g. methods, magnetic susceptibilities and spectroscopic (i.r., far-i.r., ligand field,¹Hn.m.r.) studies. Monomeric pseudo-octahedral stereochemistries for the Co^II, Ni^II and Cu^II complexes andcis square planar structures for the compounds [ML_BX₂] (M=Pd or Pt; X=Cl or Br) are assigned in the solid state. The molecules L_A and L_B behave as tetradentate chelate ligands in the Co^II, Ni^II, Cu^II and Magnus-type Pd^II and Pt^II complexes, bonding through both the pyridine and methine nitrogen atoms. A bidentateN-methine coordination of the Schiff base L_B is assigned in the [ML_BX₂] complexes (M=Pd or Pt; X=Cl or Br). The anomalous magnetic moment values of the Co^II complexes are discussed.     

Reactivity of Schiff base rhenium(V) complexes with dimethylphenylphosphine

Summary The ReOX₂L(PPh₃) complexes (X = Cl or Br and L =N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate) react with dimethylphenylphosphine (PMe₂Ph) to give ReOX₂L(PMe₂Ph) initially by displacement of the phosphine ligand and then the ReX₂L(PMe₂Ph)₂ complexes with reduction of rhenium(V) to rhenium(III). The complexes were characterized by elemental analysis, magnetic susceptibility measurements and i.r. and¹H n.m.r. spectra.     

Halogen oxidation and nitrosylation of some aldimine and ketimine carbonyl complexes of chromium and molybdenum

Summary The halogen oxidation and nitrosylation of cis-[(SB)M-(CO)₄] [M = Cr or Mo, SB = N,N-ethylenebis(p-tolualideneimine), N,N-ethylenebis(p-N,N-dimethylaminobenzalideneimine) or N,N-ethylenebis(methyl-p-methoxyphenylketimine); M = Mo, SB = N,N-ethylenebis-(cinnamylideneimine) or N,N-ethylenebis(methyl-p-methylphenylketimine)] have been studied. Halogenation of [(SB)Cr(CO)₄] yielded [(SB)CrX₂] (X = Cl, Br or I) where-as [(SB)Mo(CO)₄] gave [(SB)Mo(CO)₃X₂] (X = Br or I) and [(SB)MoX _x ] (X = I, n = 2; X = Cl or Br, n = 4). NOCl produced [(SB)Cr(NO)₂Cl₂] and [(SB)Mo(CO)₂(NO)Cl] when reacted with the corresponding [(SB)M(CO)₄]. The complexes were characterized by physico-chemical and spectroscopic measurements.     

Synthesis,characterization, electrochemistry,catalytic, and antimicrobial studies of ruthenium(III) complexes containing ONO donor ligands

A series of ruthenium(III) complexes [RuX(EPh₃)₂L] (where X = Cl or Br; E = P or As; L = deprotonated dibasic tridentate ligand) were prepared by the reaction of [RuX₃(EPh₃)₃] with Schiff bases (H₂L¹–H₂L⁴). The ligands were prepared by the condensation of N-4 phenyl/methyl semicarbazide with o-vanillin/o-hydroxy acetophenone. The complexes were characterized by elemental, physico-chemical, and electrochemical methods. Catalytic studies of these complexes for the oxidation of alcohols and aryl–aryl coupling were carried out. Antimicrobial experiments were also carried out.     

Polymetallic complexes: Part V. ONNO tetradentateN,N′-bis(acetoacetanilide)-1, 3-diaminopropane complexes of cobalt(II), copper(II) and zinc(II)

Summary Ten complexes of composition [Co₂L₂X₄] (X=Cl, Br, NO₃ or ClO₄); [Cu₂L₂(NO₃)₄]; [Zn₂L₂X₄ (X=Cl, SCN or ClO₄); [CuCl₂L] and [ZnBr₂L] have been synthesized, where L is the ONNO tetradentate ligand,N,N-bis(acetoacetanilide)-1,3-diaminopropane. The complexes have been characterised by elemental analysis, conductance, magnetic susceptibility, molecular weight and i.r., and electronic spectral measurements.Author to whom all correspondence should be directed.     

Synthesis,spectral, electrochemical and catalytic studies of new Ru(III) tetradentate Schiff base complexes

The synthesis and characterization of several hexa‐coordinated ruthenium(III) Schiff base complexes of the type [RuX(EPh₃)(L)] (X = Cl or Br; E = P or As; L = dianion of the tetradentate Schiff base) are reported. IR, EPR, electronic spectra and cyclic voltammetric data of the complexes are discussed. An octahedral geometry has been tentatively proposed for all of these complexes. The new complexes have been subjected to catalytic activity in the reaction of oxidation of alcohols in the presence of N‐methylmorpholine‐N‐oxide. Copyright © 2007 John Wiley & Sons, Ltd.     

Palladium(II) complexes with primary thioamides

Summary Palladium(II) complexes of thioacetamide, thiooxamide,N ^o,N ^o-dimethylthiooxamide and ethyl thiooxamidate have been prepared and investigated by electronic and i.r. spectroscopy. It is concluded that the ligands always act as monodentate sulphur donors, and that planar [PdL₄]X₂ (X = Cl, Br or ClO₄) compounds are formed. The(PdS) frequencies and the ligand field strengths are enhanced by electron donor groups and lowered by electron withdrawing groups.     

Cobalt(II) halide complexes with imidazolidine-2-selone derivatives

Summary CoL₂X₂ (X = Cl, Br or I) complexes were obtained by reacting cobalt(II) halides withN-methyl-,N-ethyl-,N,N-dimethyl- andN,N-diethyl-imidazolidine-2-selone. The same ligands with cobalt(II) tetrafluoroborate gave CoL₄(BF₄)₂ complexes only with the disubstituted ligands. On the basis of i.r. and electronic spectra all the complexes are considered to be Se-bonded to the metal with a tetrahedral stereochemistry, as supported by magnetic measurements and colours. The ligand field parameters (Dq, B and ) for the [CoL₄]²⁺ ion are evaluated by using the averaged ligand field approximation. The influence of the substituents on these parameters are discussed and compared with those obtained for the analogous complexes with the sulphur parent ligands.This work was partially supported by C.N.R. of Rome, Italy.     

Metal complexes of 2-(2′-or 8′-quinolyl)benzimidazoles and benzothiazoles

Summary The copper(II), cobalt(II) and nickel(II) chloride and bromide complexes with the ligands 2-(2-quinolyl)-benzimidazole (qbi), 2-(4-methyl-2-quinolyl)benzimidazole (mqbi), 2-(4-methyl-8-quinolyl)benzothiazole (m'q'bt) have been prepared and characterized by analytical methods, magnetic measurements as well as by electronic absorption, e.s.r. and far i.r. spectra. Complexes of various stoichiometries have been isolated, namely MLX₂ (all cobalt complexes with exception of the bromide qbi complex; the chloride and bromide nickel m'q'bt and mq'bt complexes), ML₂X₂ (M=Co,L=qbi and X=Br; M=Ni, L=mqbi, X=Cl or Br, M=Ni, L=qbi, X=Cl) and ML₃X₂(M=Ni, L=qbi or mqbi, X=Br). The cobalt ion has a distorted tetrahedral N₂X₂ coordination in all the CoLX₂ complexes, whereas Co(qbi)₂Br₂ is six-coordinate. The following conclusions may be drawn for the nickel complexes: in those with the 11 metal-to-ligand molar ratio the metal ion is four-or five-coordinate; in those with the 12 and 13 ratios the metal ion is hexa-coordinate, being essentially bound to four nitrogen atoms with halogens, oxygens from water or methanol or nitrogen atoms (from the third ligand) occupying the axial positions.     

Synthesis, characterization and computational studies of zinc(II)-halide complexes with a bidentate schiff base ligand (2,5-MeO-ba)2En: The crystal structure of (2,5-MeO-ba)2En

In this study four coordinated complexes of zinc(II) halides with a new symmetrical bidentate Schiff base ligand (2,5-MeO-ba)₂En are synthesized and characterized. The metal to ligand ratio of the complexes is found to be 1:1 with the formula of Zn((2,5-MeO-ba)₂En)X₂ (X = Cl (1), Br (2), I (3)). The crystal structure of the Schiff base ligand (2,5-MeO-ba)₂En is determined by X-ray crystallography from single crystal data. Also, the optimized geometries of the Schiff base ligand (2,5-MeO-ba)₂En and its zinc(II) complexes are calculated using the density functional theory method (B3LYP/6-31G). The obtained structural parameters of (2,5-MeO-ba)₂En are in agreement with the experimental data.     

Copper(I) complexes withN-methylbenzothiazole-2-thione and -2-selone

Summary N-methylbenzothiazole-2-thione (bttme) and -2-selone (btseme) form complexes with CuX₂ (X=Cl, Br, NO₃, 1/2SO₄ or BF₄). The reaction, carried out in MeOH, produces complexes of copper(I), whose stoichiometry mainly depends on the ligand. Infrared evidence shows that the coordination occurs through the exo-sulphur and selenium atoms.     

Metal complexes of pyrimidine-derived ligands — Part 6. Bischelates of cobalt(II), nickel(II) and monochelates of copper(II) with 3, 5-dimethyl-1-(4′, 6′-dimethyl-2′-pyrimidyl)pyrazole,a potential antitumour agent

Summary Cobalt(II), nickel(II) and copper(II) complexes of 3, 5-dimethyl-1-(4, 6-dimethyl-2-pyrimidyl)pyrazole (DPymPz) have been synthesized and characterized. Magnetic and electronic spectral features show that both [M(DPymPz)₂X₂]·nH₂O [M=cobalt(II) or nickel(II), X=Cl, Br, I, SCN, NO₃, ClO₄ or BF₄ andn=0 or 2] and [Cu(DPymPz)X₂(H₂O)₂] (X=Cl, Br or SCN) are essentially octahedral species. The i.r. spectra indicate that DPymPz is a neutral bidentate ligand being the pyrazolyl and one pyrimidyl ring nitrogen. The X is bonded to the central metal ion in a majority of the complexes.Part 5: N. Saha and D. Mukherjee,Polyhedron,5, 1317 (1986).     

Copper(II) halide reactions with the - NH · CS - group in heterocyclic pentaatomic rings

Summary White crystalline complexes of general formula Cu₂L₄X₂ (where X = Cl, Br and L = 1, 3-oxazolidine-2-thione, pyrrolidine-2-thione,N-methyl-1,3-imidazolidine-2-thione andN-ethyl-1,3-imidazolidine-2-thione) and CuLX (where L = 1,3-imidazolidine-2-thione) were prepared by reduction of copper(II) halides and studied by i.r. spectroscopy in the 4000–200 cm^– range. Evidence for ligand coordination to the metal through sulphur was found in each case. The(CuCI) vibration in all the chloro derivatives falls atca. 240 cm^–.     

Reaction products distribution between square-planar gold(III) complexes and N,N,N′,N′-tetramethylthiuram disulfide. Crystal structure of bis(N,N-dimethyldithiocarbamato)gold(III) bromide dihydrate, [Au(Me2NCS2)2]Br·2H2O

Summary The reactions of N,N,N,N-tetramethylthiuram disulfide (tmtds) with gold(III) complexes of the [Au(L)X₃] type [L = N-methylimidazole (N-Melm), 2-methylbenzoxazole (2-MeBO) and 2,5-dimethylbenzoxazole (2,5-diMeBO), X = Cl, Br or I] are reported, and yielded two main types of product - [Au(Me₂dtc)X₂] (A) and [Au(Me₂dtc)₂]X (B) (Me₂dtc = N,N-dimethyldithiocarbamato anion). The ratio of the product yields (B/A) depends upon the nature of the ligand (L) and halogen (X). The ratio B/A for the reaction: [Au(L)Cl₃] + tmtds = A + B, increases in the sequence N-MeIm < 2- MeBO < 2,5-diMeBO, which correlates well with the level of cytotoxic activity exhibited by the [Au(L)Cl₃] complexes. A and B were characterized by their i.r., u.v-vis. and ¹-n.m.r. spectra. The magnetic measurements were also recorded. The data support a squareplanar geometry for gold(III) complexes with the Me₂dtc ligand bonded in a bidentate fashion; a conjecture has been verified crystallographically for [Au(Me₂NCS₂)₂]-Br·2H₂O. The X-ray analysis confirmed that the complex is composed of ionic units: [Au(Me₂dtc)₂] ⁺ and Br^– and H₂O molecules. The Au—S distances are markedly similar, falling in the 2.343(4)–2.350(3) A range.