Synthesis of (2-hydroxo-5-chlorophenylaminoisonitrosoacetyl)phenyl ligands and their complexes: Spectral,thermal and solvent-extraction studies

Four different types of new ligands Ar[COC(NOH)R] _n (Ar=biphenyl, n = 1 H₂L¹; Ar=biphenyl, n = 2 H₄L²; Ar=diphenylmethane, n = 1 H₂L³; Ar=diphenylmethane, n = 2 H₄L⁴; R=2-amino-4-chlorophenol in all ligands) have been obtained from 1 equivalent of chloroketooximes Ar[COC(NOH)Cl] _n (HL¹-H₂L⁴) and 1 equivalent of 2-amino-4-chlorophenol (for H₂L¹ and H₂L³) or 2 equivalent of 2-amino-4-chlorophenol (for H₄L² and H₄L⁴). (Mononuclear or binuclear cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized with these ligands.) These compounds have been characterized by elemental analyses, AAS, infra-red spectra and magnetic susceptibility measurements. The ligands have been further characterized by ¹H NMR. The results suggest that the dinuclear complexes of H₂L¹ and H₂L³ have a metal:ligand ratio of 1:2; the mononuclear complexes of H₄L² and H₄L⁴ have a metal:ligand ratio of 1:1 and dinuclear complexes H₄L² and H₄L⁴ have a metal:ligand ratio of 2:1. The binding properties of the ligands towards selected transition metal ions (Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Pb^II, Cd^II, Hg^II) have been established by extraction experiments. The ligands show strong binding ability towards mercury(II) ion. In addition, the thermal decomposition of some complexes is studied in nitrogen atmosphere.     

Synthesis,structure, and solvent-extraction properties of tridentate oxime ligands and their cobalt(II), nickel(II), copper(II), zinc(II) complexes

Synthesis of four different types of ligands Ar[COC(NOH)R] _n (Ar = biphenyl, n = 1, HL¹; Ar = biphenyl, n = 2, H₂L²; Ar = diphenylmethane, n = 1, HL³; Ar = diphenylmethane, n = 2, H₂L⁴; R = furfurylamine in all ligands) and their dinuclear Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ complexes is reported herein. These compounds were characterized by elemental analysis, ICP-OES, FT-IR spectra, and magnetic susceptibility measurements. The ligands were further characterized by ¹H NMR. The results suggest that dinuclear complexes of HL¹ and HL³ have a metal to ligand mole ratio of 2: 2 and dinuclear complexes H₂L² and H₂L⁴ have a metal to ligand mole ratio of 2: 1. Square pyramidal or octahedral structures are proposed for complexes of oxime ligands. Furthermore, extraction abilities of the four ligands were also evaluated in chloroform using selected transition metal picrates such as Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺. The ligands show strong binding ability towards Hg²⁺ and Cu²⁺ ions.     

Synthesis and Spectroscopic Characterisation of a New Class of Heterobimetallic Zirconocene(IV) Compounds

Reactions of Cp₂ZrCl₂ with homometallic complexes of aluminium containing one residual hydroxy group Al(OGO)(OGOH) and Al(L)(OGOH) [where G=G¹=CMe₂CMe₂ (1a); G=G²=CMe₂CH₂CHMe (1b); G= G³=CMe₂CH₂CH₂CMe₂ (1c) and L=L¹=OC₆H₄CH=NCH₂CH₂O, G=G¹ (2a); L=L¹, G=G² (2b); L=L¹, G=G³ (2c); L=L²=OC₁₀H₆CH=NCH₂CH₂O, G=G¹ (2d); L=L², G=G² (2e); L=L², G=G³ (2f)] in THF using Et₃N as HCl acceptor affords novel heterobimetallic compounds of the types Al(OGO)₂Zr(Cl)Cp₂ and Al(L)(OGO)Zr(Cl)Cp₂, respectively. All of these derivatives have been characterised by elemental analyses, molecular weight measurements, and spectroscopic [IR, NMR (¹H and ²⁷Al)] studies.     

Synthesis of copper and zinc chloride complexes with tri- and tetranitrofluorenones. Crystal and molecular structure of 2,4,5,7-tetranitrofluorenone

The complexes MLCl₂ · nH₂O and ML₂Cl₂ · nH₂O, where M = Cu(II), Zn and n = 1–4, were isolated and identified due to the reactions of Cu(II) and Zn(II) chlorides with 2,4,7-trinitrofluorene (L¹), 2,4,7-trinitrofluorenone (L^1a), and 2,4,5,7-tetranitrofluorene (L²). It was shown that, during complex formation, L¹ and L² were oxidized to fluorenones (L^1a, L^2a) and as neutral ligands formed 1: 1 and 2: 1 complexes with metal cations. A single crystal of tetranitrofluorenone (L^2a) was isolated, and its crystal and molecular structure was determined. The complexes were studied by X-ray powder diffraction analysis, their spectral (IR and UV) characteristics were determined, and the structures for the complexes were proposed.     

Tetradentate asymmetric Schiff bases and their Ni(II) and Fe(III) complexes

Three asymmetric Schiff-base tetradentate diimines H₂L¹, H₂L², and H₂L³ [(2-OH)C₆H₄N=CHC₆H₄2-N=CHC₆H₃(2-OH)(5-X), X?=?H, CH₃, Cl respectively] have been synthesized by a two step process. The reaction of 2-hydroxy aniline with 2-nitro-benzaldehyde in EtOH gave the starting Schiff base, 2-hydroxy-N-(2-nitrobenzylidene)aniline (SB-NO₂), which was reduced into the amino derivative (SB-NH₂) in solution. Reacting SB-NH₂ with 2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde and 2-hydroxy-5-chlorobenzaldehyde gave the three new ligands H₂L¹, H₂L², and H₂L³ respectively. Their dimeric, binuclear metal complexes with Ni(II) and Fe(III) have also been synthesized. The ligands and their complexes were characterized by elemental analyses, LC–MS, IR, electronic, ¹H and ¹³C-NMR spectra, TGA, conductivity and magnetic measurements. All of the spectroscopic, analytical and other data indicate octahedral geometry M₂L₂(H₂O)X₂ (M: Ni,Co;X: Cl or H₂O), except for NiL² which is monomeric. Antimicrobial activities of the ligands and the complexes were evaluated against five bacteria. While the ligands and the Ni complexes are inactive towards Pseudomonas aeruginosa and Staphylococcus aureus, Fe complexes are active; only Fe complexes are inactive against Escherichia coli. All of the compounds have antimicrobial activities against Bacillus subtilis, and Yersinia enterecolitica.     

Triple Helicates with Golden Strands: Self‐Assembly of M2Au6 Complexes from Gold(I) Metallaligands and Iron(II), Cobalt(II) or Zinc(II) Cations

Alkynyl gold(I) metallaligands [(AuC≡Cbpyl)₂(μ‐diphosphine)] (bpyl=2,2′‐bipyridin‐5‐yl; diphosphine=Ph₂P(CH₂)_nPPh₂, [n=3 (L^Pr), 4 (L^Bu), 5 (L^Pent), 6 (L^Hex)], dppf (L^Fc), Binap (L^Binap) and Diop (L^Diop)) react with MX₂ (M=Fe, Zn, X=ClO₄; M=Co, X=BF₄) to give triple helicates [M₂(L^R)₃]X₄. These complexes, except those containing the semirigid L^Binap metallaligand, present similar hydrodynamic radii (determined by diffusion NMR spectroscopy measurements) and a similar pattern in the aromatic region of their ¹H NMR spectra, which suggests that in solution they adopt a compact structure where the long and flexible organometallic strands are folded. The diastereoselectivity of the self‐assembly process was studied by using chiral metallaligands, and the absolute configuration of the iron(II) complexes with L^Binap and L^Diop was determined by circular dichroism spectroscopy (CD). Thus, (R)‐L^Binap or (S)‐L^Binap specifically induce the formation of (Δ,Δ)‐[Fe₂((R)‐L^Binap)₃](ClO₄)₄ or (Λ,Λ)‐[Fe₂((S)‐L^Binap)₃](ClO₄)₄, respectively, whereas (R,R)‐ or (S,S)‐L^Diop give mixtures of the ΔΔ‐ and ΛΛ‐diastereomers. The ΔΔ helicate diastereomer is dominant in the reaction of Fe^II with (R,R)‐L^Diop, whereas the ΛΛ isomer predominates in the analogous reaction with (S,S)‐L^Diop. The photophysical properties of the new dinuclear alkynyl complexes and the helicates have been studied. The new metallaligands and the [Zn₂(L^R)₃]⁴⁺ helicates present luminescence from [π→π*] excited states mainly located in the C≡Cbpyl units.     

Synthesis,characterization, and biological properties of Ni(II), Co(II), and Cu(II) complexes of Schiff bases derived from 4-aminobenzylamine

New Schiff bases, N,N′-bis(salicylidene)-4-aminobenzylamine (H₂L¹), N,N′-bis(3-methoxysalicylidene)-4-aminobenzylamine (H₂L²), and N,N′-bis(4-hydroxysalicylidene)-4-aminobenzylamine (H₂L³), with their nickel(II), cobalt(II), and copper(II) complexes have been synthesized and characterized by elemental analyses, electronic absorption, FT-IR, magnetic susceptibility, and conductance measurements. For the ligands, ¹H and ¹³C NMR and mass spectra were obtained. The tetradentate ligands coordinate to the metal ions through the phenolic oxygen and azomethine nitrogens. The keto-enol tautomeric forms of the Schiff bases H₂L¹, H₂L², and H₂L³ have been investigated in polar and apolar solvents. All compounds were non-electrolytes in DMSO (～10^?3 M) according to the conductance measurements. Antimicrobial activities of the Schiff bases and their complexes have been tested against Acinobacter baumannii, Pseudomonas aeruginosa, Micrococcus luteus, Bacillus megaterium, Corynebacterium xerosis, Staphylococcus aureus, Escherichia coli, Candida albicans, Rhodotorula rubra, and Kluyveromyces marxianus by the disc diffusion method; biological activity increases on complexation.     

Synthesis and physiochemical studies on binuclear Cu(II) complexes derived from 2,6-[(N-phenylpiperazin-1-yl)methyl]-4-substituted phenols

Preparation of the ligands HL¹ = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-ethylphenol; HL² = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-methoxyphenol and HL³ = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-nitrophenol are described together with their Cu(II) complexes with different bridging units. The exogenous bridges incorporated into the complexes are: hydroxo [Cu₂L(OH)(H₂O)₂](ClO₄)₂.H₂O (L¹=1a, L² =1b, L³ =1c), acetato [Cu₂L(OAc)₂]ClO₄.H₂O (L¹ =2a, L² =2b, L³ =2c) and nitrito [Cu₂L¹(NO₂)₂(H₂O)₂]ClO₄.H₂O (L¹=3a, L² =3b, L³ =3c). Complexes1a,1b,1c and2a,2b,2c contain bridging exogenous groups, while3a,3b,3c possess only open μ-phenolate structures. Both the ligands and complexes were characterized by spectral studies. Cyclic voltammetric investigation of these complexes revealed that the reaction process involves two successive quasireversible one-electron steps at different potentials. The first reduction potential is sensitive to electronic effects of the substituents at the aromatic ring of the ligand system, shifting to positive potentials when the substituents are replaced by more electrophilic groups. EPR studies indicate very weak interaction between the two copper atoms. Various covalency parameters have been calculated.     

Synthesis,spectral studies,and antimicrobial activity of binary and ternary Cu(II), Ni(II), and Fe(III) complexes of new hexadentate Schiff bases derived from 4,6-diacetylresorcinol and amino acids

Two new hexadentate N₂O₄ donor Schiff bases, H₄L¹ and H₄L², were synthesized by condensation of 4,6-diacetylresorcinol with glycine and alanine, respectively. The structures of the ligands were elucidated by elemental analyses, IR, ¹H NMR, electronic, and mass spectra. Reactions of the Schiff bases with copper(II), nickel(II), and iron(III) nitrates in 1 : 2 molar ratio gave binuclear metal complexes and, in the presence of 8-hydroxyquinoline (8-HQ) or 1,10-phenanthroline (Phen) as secondary ligands (L′), mixed-ligand complexes in two molar ratios 1 : 2 : 2 and 1 : 2 : 1 (L¹/L² : M : L′). The complexes were characterized by elemental and thermal analyses, IR, electronic, mass, and ESR spectral studies, as well as conductivity and magnetic susceptibility measurements. The spectroscopic data reveal that the Schiff-base ligands were dibasic or tetrabasic hexadentate ligands. The coordination sites with the metal ions are two azomethine nitrogens, two oxygens of phenolic groups, and two oxygens of carboxylic groups. Copper(II) complexes were octahedral and square planar while nickel(II) and iron(III) complexes were octahedral. The Schiff bases, H₄L¹ and H₄L², and some of their metal complexes showed antibacterial activity towards Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Pseudomonas fluorescens and Pseudomonas phaseolicola) bacteria and antifungal activity towards the fungi Fusarium oxysporium and Aspergillus fumigatus.     

New glyoxime derivatives and their transition metal complexes

Two new vic-dioxime ligands and their complexes with Co⁺², Ni⁺², Cu⁺², Cd⁺², and Zn⁺² ions were synthesized. Primer amines (3,4-methylenedioxaaniline and 4-methylbenzylamine) reacted with antichloroglyoxime to give 3,4-methylenedioxaphenylaminoglyoxime (H₂L¹) and N-(4-methylbenzyl)aminoglyoxime (H₂L²) ligands. Structures of the ligands and their complexes are proposed based on elemental analyses, IR, UV-Vis, and ¹H NMR spectra, magnetic susceptibility measurements, and thermogravimetric analyses (TGA). The article was submitted by the authors in English.     

Cuprous complexes and dioxygen,VII. Competition between one- and two-electron reduction of O2 in the autoxidation of Cu(1-methyl-2-hydroxymethyl-imidazole)2+

The complexation of 1-methyl-2-hydroxymethyl-imidazole (L) with Cu(I) and Cu(II) has been studied in aqueous acetonitrile (AN). Cu(I) forms three complexes, Cu(AN)L⁺, CuL₂⁺, and Cu(AN)H_?1L, with stability constants logK(Cu(AN)⁺ + L ? Cu(AN)L⁺) = 4.60 ± 0.02, logβ₂ = 11.31 ± 0.04, and logK(Cu(AN)H_?1L+H⁺ ? Cu(AN)L⁺) = 10.43 ± 0.08 in 0.15M AN. The main species for Cu(II) are CuL²⁺, CuH_?1L⁺, CuH_?1L₂⁺, and CuH_?2L₂. The autoxidation of CuL₂⁺ was followed with an oxygen sensor and spectrophotometrically. Competition between the formation of superoxide in a one-electron reduction of O₂ and a path leading to H₂O₂ via binuclear (CuL₂)₂O was inferred from the rate law with k_a = (2.31 ± 0.12) · 10⁴M ^?2S ^?1, k_b = (1.0 ± 0.2) · 10³M ^?1, k_c = (2.85 ± 0.07) · 10²M ^?2S ^?1, k_d = 3.89 ± 0.14M ^?1S ^?1, k_e = 0.112 ± 0.004, k_f = (2.06 ± 0.24) · 10^?10M S ^?1, k_g = (1.35 ± 0.07) · 10^?7 S ^?1, and k_h = (6.8 ± 1.4) · 10^?7M ^?1 S ^?1.     

Synthesis,characterization and biological studies of oxovanadium(IV) complexes with triazole‐derived Schiff bases

A series of triazole‐derived Schiff bases (L¹–L⁵) and their oxovanadium(IV) complexes have been synthesized. The chemical structures of Schiff bases were characterized by their analytical (CHN analysis) and spectral (IR, ¹H and ¹³C NMR and mass spectrometry) data, and oxovanadium(IV) complexes were elucidated by their physical (magnetic susceptibility and conductivity), analytical (CHN analysis), conductance measurements and electronic spectral data. The molar conductivity data indicate the oxovanadium(IV) complexes to be non‐electrolyte. The Schiff bases act as bidentate and coordinate with the oxovanadium(IV)‐forming stoichiometry of a complex as [M (L‐H)₂] where M = VO and L = L¹–L⁵ in a square‐pyramidal geometry. The agar well diffusion method was used for in vitro antibacterial screening against E. coli, S. flexenari, P. aeruginosa, S. typhi, S. aureus and B. subtilis and for antifungal activity against T. longifucus, C. albican, A. flavus, M. canis, F. solani and C. glaberata. The biological activity data show the oxovanadium(IV) complexes to be more antibacterial and antifungal than the parent Schiff bases against one or more bacterial and fungal strains. Copyright © 2009 John Wiley & Sons, Ltd.     

Selective [2+1+1] Fragmentation of P4 by heteroleptic Metallasilylenes

Small-molecule activation by low-valent main-group element compounds is of general interest. We here report the synthesis and characterization (¹H, ¹³C, ²⁹Si NMR, IR, sc-XRD) of heteroleptic metallasilylenes L¹(Cl)MSiL² (M=Al 1 , Ga 2 , L¹=HC[C(Me)NDipp]₂, Dipp=2,6-ⁱPr₂C₆H₃; L²=PhC(N^tBu)₂). Their electronic nature was analyzed by quantum chemical computations, while their promising potential in small-molecule activation was demonstrated in reactions with P₄, which occurred with unprecedented [2+1+1] fragmentation of the P₄ tetrahedron and formation of L¹(Cl)MPSi(L²)PPSi(L²)PM(Cl)L¹ (M=Al 3 , Ga 4 ).     

Synthesis,electrochemical and antimicrobial studies of mono and binuclear iron(III) and oxovanadium(IV) complexes of [ONO] donor tridentate Schiff-base ligands

Tridentate Schiff bases (H₂L¹ or H₂L²) were derived from condensation of acetylacetone and 2-aminophenol or 2-aminobenzoic acid. Binuclear square pyramidal complexes of the type [M₂(L¹)₂]?·?nH₂O (M?=?Fe–Cl, n?=?0; M?=?VO, n?=?1) were accessed from interaction of H₂L¹ with anhydrous FeCl₃ and VOSO₄?·?5H₂O, respectively. A similar reaction with H₂L², however, produced mononuclear complexes [ML²(H₂O) _x ]?·?nH₂O (M=Fe–Cl, x?=?0, n?=?0; M=VO, x?=?1, n?=?1). The compounds were characterized using elemental analysis, FT-IR, UV-Vis, and NMR (for ligand only), and mass spectroscopies and solution electrical conductivity studies. Magnetic susceptibility measurements suggest antiferromagnetic exchange in binuclear Fe(III) and VO(IV) complexes. Thermo gravimetric analysis (TGA) provided unambiguous evidence for the presence of coordinated as well as lattice water in [VOL²(H₂O)]?·?H₂O. Cyclic voltammetric studies showed well-defined redox processes corresponding to Fe(III)/Fe(II) and VO(V)/VO(IV). In vitro antimicrobial activities of the compounds were investigated against Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeroginosa, Escherichia coli, Bacillus subtilis, and Proteus vulgaris. H₂L¹ and its binuclear complexes exhibited pronounced activity against all the microorganisms tested.     

Coordination and Hydroboration of Ru(II)-Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

Treatment of [Cp*RuCl₂]₂, 1 , [(COD)IrCl]₂, 2 or [(p-cymene)RuCl₂]_2, 3 (Cp*=η⁵-C₅Me_5, COD= 1,5-cyclooctadiene and p-cymene=η⁶-ⁱPrC₆H₄Me) with heterocyclic borate ligands [Na[(H₃B)L], L₁ and L₂ ( L₁ : L=amt, L₂ : L=mp; amt=2-amino-5-mercapto-1,3,4-thiadiazole, mp=2-mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L₁ and L₂ afforded dihydridoborate species [L^AM(μ-H)₂BHL] 4 – 6 ( 4 : L^A=Cp*, M=Ru, L=amt; 5 : L^A=Cp*, M=Ru, L=mp; 6 : L^A=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L₂ yielded cis- and trans-bis(dihydridoborate) species, [Ru{(μ-H)₂BH(mp)}₂], cis- 7 and trans- 7 . The isolation and structural characterization of fac- and mer-[Ru{(μ-H)₂BH(mp)}{(μ-H)BH(mp)₂}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis-and trans- 7 , they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti-Markovnikov addition products, 10 a – d .     

Complex Formation of 2, 6‐Bis‐(2′‐hydroxyphenyl)pyridine with AlIII,FeIII and CuII

Complex formation of 2, 6‐bis(2′‐hydroxyphenyl)pyridine (H₂Lⁱ) with Fe³⁺ and Cu²⁺ was investigated in a H₂O/DMSO medium (mole fraction x_DMSO = 0.2) by potentiometric and spectrophotometric methods. The pK_a values of [H₃Lⁱ]⁺ are 2.25, 10.51 and 14.0 (25 °C, 0.1 M KCl). The formation constants of [Fe^III(Lⁱ)]⁺ and [Cu^II(Lⁱ)] (25 °C, 0.1 M KCl) are log β₁ = 21.5 for Fe³⁺ and log β₁ = 18.5 for Cu²⁺. The crystal structures of [Al(Lⁱ)₂Na(EtOH)₃], [Fe(Lⁱ)₂Na(EtOH)₃], and [Cu(Lⁱ)(py)]₂ were investigated by single‐crystal X‐ray diffraction analyses. The Fe^III and the Al^III compound are isotypic and crystallize in the monoclinic space group P2₁/n. Al‐compound (215 K): a = 12.599(3) Å, b = 16.653(3) Å, c = 17.525(4) Å, β = 100.27(3)°, Z = 4 for C₄₀H₄₀AlN₂NaO₇; Fe‐compound (293 K): a = 12.753(3) Å, b = 16.715(3) Å, c = 17.493(3) Å, β = 99.68(3)°, Z = 4 for C₄₀H₄₀FeN₂NaO₇. Both compounds contain a homoleptic, anionic bis‐complex [M(Lⁱ)₂]^‐ of approximate D₂ symmetry. The Cu compound crystallized as an uncharged, dinuclear and centrosymmetric [Cu(Lⁱ)(py)]₂ complex in the monoclinic space group P2₁/n with (293 K) a = 13.386(3) Å, b = 9.368(2) Å, c = 14.656(3) Å, β = 100.65(3)°, Z = 2 for C₄₄H₃₂Cu₂N₄O₄. The structural properties and in particular the possible influence of the ligand geometry on the stability of the metal complexes is discussed.     

基于柔性硫代二乙酸配体的镧系配位聚合物的合成、结构和荧光性质

利用硫代二乙酸配体[thiodiacetic acid = H2tda]与稀土盐[SmCl3·nH2O,DyCl3·nH2O]反应合成了两种新型稀土配合物[Ln2(tda)3(H2O)2]n (Ln = Sm(1), Dy(2)),单晶结构分析表明：两个配合物结构相同,均是通过以共边多面体[Ln2O16]为基本单元的一维稀土金属链拓展而成的二维层状结构。有趣的是,在配合物中,硫代二乙酸配体展现了两种配位模式：双“顺-顺桥式双齿、螫合-桥式三齿”模式和双“螯合-桥式三齿、顺-反桥式双齿”模式;正是通过配体这两种配位方式的连接,上述一维稀土金属链扩展为具有(3,4,5,6)连接(47·68)(44·66) (45·6)(46)(43)拓扑结构的二维网络。荧光性质研究表明,在室温下镝配合物呈现黄色荧光,钐配合物呈现鲑鱼粉色荧光。     

Synthesis,characterization, and biological investigation of new mixed-ligand complexes

A novel series of mixed-ligand complexes of 5,5′-{(1E,1E′)-1,4-phenelynebis(diazene-2,1-diyl)}bis(quinolin-8-ol) (H₂L₁) as a primary ligand and 4-aminoantipyrine(L₂) as a secondary ligand with Mn(II) ion were prepared using two general formulae: [Mn₂(H₂L₁)₂(L₂)₂X₄].4Cl (X = OH₂( 1 ), ONO₂⁻( 2 ), Cl=nil; OAc( 3 ), Cl = nil) and [Mn₂(H₂L₁)(L₂)₂(O₂SO₂)₂]( 4 ). Free ligands and their complexes were characterized. Electronic absorption spectra of the mixed-ligand complexes indicate a distorted octahedral geometry around the central metal ion, and the anions X⁻ are in the axial positions for all compounds. The ligands behave in a neutral bidentate manner, through nitrogen atoms and oxygen atoms of the carbonyl group (L₂), whereas H₂L₁ coordinated through nitrogen and OH groups as a neutral bidentate ligand. All complexes do not contain coordinated water molecules, but complex ( 1 ) contains four water molecules. The water molecules are removed in a single step. The complexes exhibited magnetic susceptibility corresponding to five unpaired electrons. The antimicrobial activity of the Mn(II) mixed-ligand complexes ( 1–4 ) against two gram-positive bacteria, three local gram-negative bacteria, and three fungi species was tested. Mn(II) mixed-ligand complex ( 2 ) exhibited significant antibacterial activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas sp. Mixed-ligand complex ( 2 ) exhibited a high potential cytotoxicity against the growth of human lung cancer cells.     

Copper(II), nickel(II) and cobalt(II) complexes of 5,5-dimethylcyclohexane-1,2,3-trione-2-arylhydrazones

Summary Copper(II), nickel(II) and cobalt(II) perchlorate complexes of 5,5-dimethylcyclohexane-1,2,3-trione-2-(p-nitrophenyl-hydrazone) (HL¹), 5,5-dimethyl-cyclohexane-1,2,3-trione-2-(p-chlorophenylhydrazone) (HL²), 5,5-dimethylcyclohexane-1,2,3-trione-2-(o-chlorophenylhydrazone) (HL⁴), 5,5-dimethylcyclohexane-1,2,3-trione-2-(o-methylphenyl-hydrazone) (HL⁵) and 5,5-dimethylcyclohexane-1,2,3-trione-2-(m-methylphenylhydrazone) (HL⁶) have been prepared, and characterized using analytical, spectral and magnetic measurements. The data reveal that the reaction of Cu(ClO₄)₂ (1 mol) in EtOH, with all ligands, produces complexes of the type CuL(ClO₄)(H₂O).nH₂O. Nickel(II) and cobalt(II) perchlorates react only with HL¹ and HL² to produce the complexes ML(ClO₄)(H₂O)₃ (where M = Ni^II, L = L^– and L², M = Co^II, L = L¹) and Co(HL₂)₂-(ClO₄)₂.2H₂O. The spectral data show that the ligands behave as monobasic bidentate in their azo forms, except HL² which reacts with cobalt(II) as a neutral bidentate ligand in its hydrazone form.     

Reactions of bis(isopropylxanthato)nickel(II) with nitrogen-donor ligands—II

New complexes of bivalent nickel with isopropylxanthates and nitrogen-donor ligands of composition [Ni(Prⁱxa)₂(L)], [Ni(Prⁱxa)₂(L¹)₂], [Ni(L²)₂](Prⁱxa)₂, and [Ni(L³)₃] (Prⁱxa)₂ have been synthesized, where Prⁱxa = i-C₃H₇OCS₂⁻, L = 1,2-diaminopropane (1,2-pn), N,N,N′,N′=tetramethylethylenediamine (tmen) or 4,4′-bipyridine (4,4′-bipy), L¹ = pyridine (py), L² = diethylenetriamine (dien) and L³ = ethylenediamine (en), 1,2-diaminopropane or 1,10-phenanthroline (phen). The compounds have been characterized by elemental analysis, IR and UV-vis spectroscopy, magnetochemical measurements, molar conductivity and thermal analysis. The compounds containing the complex cation have been one-electron irreversibly oxidized using cyclic voltammetry. The crystal and molecular structures of [Ni(Prⁱxa)₂(tmen)] and [Ni(phen)₃](Prⁱxa)₂ have been elucidated.