X-ray structure and spectroscopic characterization of divalent dinuclear cobalt complexes containing carboxylate- and phosphodiester- auxiliary bridges

Two dinuclear spin-coupled divalent cobalt complexes, [Co₂(P1-O)(μ₂-OAc)](ClO₄)₂, (1) and [Co₂(P1-O)(μ₂-BNPP)](ClO₄)₂, (2) containing μ-1,3 acetate (OAc) and bis(4-nitrophenyl)phosphate (BNPP) auxiliary bridges, respectively, were synthesized by the reaction of a classic dinucleating ligand, P1-OH with cobalt(II) perchlorate in presence of acetic acid/bis(4-nitrophenyl)phosphate. They were characterized by single crystal X-ray diffraction, to show a trigonal bipyramidal geometry around each cobalt center and the intervening bridging atoms that are responsible for spin-transfer between the two divalent cobalt centers; the alkoxo oxygen donor occupies an equatorial position, and the auxiliary ligand oxygens (OAc/BNPP) occupy the axial positions. Solution state magnetic moment measurement together with UV-Vis/NIR spectra revealed a high-spin ground state (S = 3/2) for Co(II) in these compounds. Complexes 1 and 2 show interesting ¹H NMR spectral features of resonances with relatively narrower linewidths in conjunction with a sizable chemical shift dispersion of −5 and 265 ppm. Complex 2 containing the bis(4-nitrophenyl)phosphate auxiliary bridge showed narrower spectral window than complex 1 that has the acetate auxiliary bridge.     

The synthesis and X-ray structure of a chiral rhodium-NHC complex: Implications for the use of NHCs in asymmetric hydroformylation catalysis

An optically active N-heterocyclic carbene (NHC) has been metallated with [RhCl(COD)]₂ to give a rhodium(I) monocarbene substituted complex. This complex has been fully characterized by ¹H and ¹³C NMR spectroscopy and by single-crystal X-ray analysis. Preliminary tests of hydroformylation of styrene catalyzed with this compound have shown that branched to linear aldehyde ratio was rather low 0.67 (40%) and that the enantiomeric excess measured on the corresponding alcohols was only 10%. In the presence of an excess of triphenylphosphine, the ratio of branched to linear aldehyde increased markedly (91%) whereas the enantioselectivity of the reaction remained almost unchanged (12.5%).     

Crystal structure of the novel neutral octahedral complex [(4′-(4-tbutylphenyl)-2,2′:6′,2″-terpyridine)Rh(Br)(acetonyl)2]

The synthesis and the crystal and molecular structure of a unique Rh(III) complex, [Rh^III(Br)(acetonyl)₂(4′-(4-tbutylphenyl)-2,2′:6′,2″-terpyridine)] (1) are described. The yellow crystals separate from the acetone solution of the starting complex [Rh(Br)(COD)]₂ and the ligand 4′-(4-tbutylphenyl)-2,2′:6′,2″-terpyridine after standing at room temperature for a prolonged period of time. The crystals are almost insoluble in all common organic solvents. The single-crystal X-ray structure determination shows that compound 1 is the first Rh-complex with a terdentate nitrogen ligand and two axially oriented, σ-bound acetonyl groups. DFT-calculations on a model complex without the substituent on the terpyridine ligand were carried out and agree very well with the X-ray results, confirming the constitution and geometry of the molecule.     

Isolation of a singly oxo-bridged Fe(III) dinuclear complex: Synthesis, crystal structure, spectroscopic and magnetic studies

The μ-oxo dinuclear complex {Fe₂O(tptz)₂[N(CN)₂]₂(NO₃)₂} (1) (where tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) has been synthesised and characterised by elemental analysis, FT-IR, UV-vis, cyclic voltammetry, Mössbauer spectroscopy, and variable-temperature magnetic susceptibility measurements and single crystal X-ray diffraction. The iron centres have a pentagonal-bipyramidal geometry. The dimeric neutral complex exhibits typical Fe-μ-O bond lengths of 1.763(1) Å and a bridge angle of 180.00°. The Fe?Fe separation is 3.526(3) Å. The Mössbauer spectrum at room temperature consists of one quadrupole doublet with an isomer shift of 0.41 mm/s and a quadrupole splitting of 1.12 mm/s. Variable-temperature magnetic susceptibility measurements have been measured in the temperature range 300-2 K, revealing an intramolecular antiferromagnetic coupling (J = −211.6 cm⁻¹).     

X-ray and Fe Mössbauer study on a Fe(III) complex of 2-acetyl-1,3-indandione

Single-crystal X-ray structure of an iron(III) complex of 2-acetyl-1,3-indandione is resolved which reveals that a racemic mixture, composed of Δ-fac and Λ-fac stereoisomers, is formed. Both species have octahedral geometry, but slightly distinguishable. Detailed Mössbauer data indicate a high-spin electronic structure of the Fe(III) centres Fe1 and Fe2 with spin-spin magnetic relaxation process. Two different approaches for computer processing of the experimental Mössbauer spectra are considered.     

Mono- and dinuclear Fe(III) complexes with the N2O2 donor 5-chlorosalicylideneimine ligands; synthesis, X-ray structural characterization and magnetic properties

Two novel monomeric [C₁₈H₁₇Cl₃N₂O₂Fe] (1) and dimeric [C₃₈H₃₆N₄O₄Cl₆Fe₂] (2) Fe(III) tetradentate Schiff base complexes have been synthesized and their crystal structures have been determined by single crystal X-ray diffraction analysis. In complex (1) the Schiff base ligand coordinates toward one iron atom in a tetradentate mode and each iron atom is five coordinated with the coordination geometry around iron atom which can be described as a distorted square pyramid. The presence of a short (2.89 Å) non-bonding interatomic Fe···O distances between adjacent monomeric Fe(III) complexes results in the formation of a dimer. Structural analysis of compound (2) shows that the structure is a centrosymmetric dimer in which the six coordinated Fe(III) atoms are linked by μ-phenoxo bridges from one of the phenolic oxygen atoms of each Schiff base ligand to the opposite metal center. The variable-temperature (2-300 K) magnetic susceptibility (χ) data of these two compounds have been investigated. The results show that for both complexes Fe(III) centers are in the high spin configuration (S = 5/2) and indicate antiferromagnetic spin-exchange interaction between Fe(III) ions. The obtained results are briefly discussed using magnetostructural correlations developed for other class of iron(III) complexes.     

Design, synthesis and in vitro cytotoxicity of novel dinuclear platinum(II) complexes

Five dinuclear platinum(II) complexes with a novel chiral ligand, 2-(((1R,2R)-2-aminocyclohexylamino)methyl)phenol (HL), were designed, prepared and spectrally characterized. In vitro cytotoxicity of all the resulting platinum(II) compounds was evaluated against human HEPG-2, A549 and HCT-116 cell lines, respectively. Results indicated that all compounds showed positive biological activity. Particularly, compound D4 has lower IC₅₀ values than carboplatin toward HEPG-2 and A549, while compound D5 shows better activity than carboplatin against A549.     

Synthesis, characterization, cytotoxic activity and DNA binding properties of the novel dinuclear cobalt(III) complex with the condensation product of 2-acetylpyridine and malonic acid dihydrazide

A novel dinuclear cobalt(III) complex with the condensation product of 2-acetylpyridine and malonic acid dihydrazide, N′,N′²-bis[(1E)-1-(2-pyridyl)ethylidene]propanedihydrazide was synthesized and characterized by elemental analysis, spectroscopy (NMR and infrared), and X-ray crystal analysis. The complex showed a moderate activity towards Artemia salina. The highest cytotoxic potential of the complex was observed on the epithelial breast cancer (MDA-361) cell line. The investigated complex induced apoptosis, the early apoptotic cells comprising 28.18%, compared to 5.64% of control cells in the same phase. The interaction of the complex with calf thymus DNA (CT-DNA) was monitored by blue shift and hyperchromism in the UV-vis spectra. The observed intrinsic binding constant (K_b = 4.2 × 10⁵ M^− 1) together with structural analysis of the complex indicate the groove binding.     

Macrocyclic dinuclear Zn(II) complexes: synthesis, structure and hydrolysis of tris(p-nitrophenyl) phosphate

A series of mono- and dinuclear zinc complexes of 3,6,9,17,20,23-hexaaza-29,30-dihydroxy-13,27-dimethyl-tricyclo[23,3,1^11,15]triaconta-1(28),11,13,15(30),25,26-hexaene (H₂L or BDBPH) have been defined in solution by potentiometry. The crystal structure of [Zn₂C₂₆H₄₀N₆O₂(CH₃OH)₂]·Br₂ has been determined by X-ray. Each zinc ion is coordinated to three nitrogen atoms, a bridged-phenolic oxygen atom, and a methanolic oxygen atom, which define a six-coordinated octahedron. Bond lengths of ZnN are in the range of 2.104(3)-2.120(3) Å and distances between Zn and O (bridged-phenolic oxygen) are 2.052(2), 2.062(2) Å, respectively. The dinuclear complexes: [Zn₂L]²⁺ and [Zn₂L(OH)]⁺ play crucial roles in hydrolytic reaction of tris(4-nitrophenyl)phosphate. A possible mechanism showed that [Zn₂L(OH)]⁺ acts as a nucleophile and [Zn₂L]²⁺ stabilizes the formation of the intermediate: [Zn₂L-BNP].     

Catalytic properties of water-soluble rhodium and iridium complexes: the influence of the ligand structure

Rhodium and iridium complexes of trisulfonated triarylphosphanes, TPPTS (tris(3-sulfonatophenyl)phosphane), T(p-A)PTS (tris(3-sulfonato-4-methoxyphenyl)phosphane), T(2,4-X)TS (tris(2,4-dimethyl-5-sulfonatophenyl)phosphane), have been tested in biphasic hydrogenation of aldehydes. T(2,4-X)TS could not stabilize the rhodium complex under the applied conditions. Guanidium salt of T(2,4-X)TS has been characterized by X-ray crystallography, and Tolman cone angle of the phosphane has been determined from crystallographic data. The large cone angle (196°, 210°) explains the instability of the rhodium complex. Contrary to the T(2,4-X)TS/rhodium system, the T(2,4-X)TS/iridium catalyst has been found to be stable and effective in hydrogenation of benzaldehyde and caproaldehyde.     

Squarato-metal(II) complexes. 1: Structural and magnetic characterization of squarato-bridged dinuclear nickel(II) and copper(II) complexes

A new series of dinuclear squarato-bridged nickel(II) and copper(II) complexes [Ni₂(2,3,2-tet)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂ (1), [Ni₂(aepn)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂ (2), [Cu₂(pmedien)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂.4H₂O (3) and [Cu₂(DPA)₂(μ_1,2-C₄O₄)(H₂O)₂](ClO₄)₂ (4) where is the dianion of 3,4-dihydroxycyclobut-3-en-1,2-dione (squaric acid), 2,3,2-tet = 1,4,8,11-tetraazaundecane, aepn = N-(2-aminoethyl)-1,3-propanediamine, pmedien = N,N,N′,N″,N″-pentamethyldiethylenetriamine and DPA = di(2-pyridylmethyl)amine were synthesized and structurally characterized by X-ray crystallography. The spectral and structural characterization as well as the magnetic behaviour of these complexes is reported. In this series, structures consist of the groups as counter ions and the bridging the two M(II) centers in a μ-1,3- (1-3) and in a μ-1,2-bis(monodentate) (4) bonding fashions. The coordination geometry around the Ni(II) ions in 1 and 2 is six-coordinate with distorted octahedral environment achieved by N atoms of the amines and by one or two oxygen atoms from coordinated water molecules, respectively. In the Cu(II) complexes 3 and 4, a distorted square pyramidal geometry is achieved by the three N-atoms of the aepn or DPA and by an oxygen atom from a coordinated water molecule. The electronic spectra of the complexes in aqueous solutions are in complete agreement with the assigned X-ray geometry around the M(II) centers. The complexes show weak antiferromagnetic coupling with ∣J∣ = 1.8-4.2 cm⁻¹ in the μ-1,3- bridged squarato compounds 1-3, and J = −16.1 cm⁻¹ in the corresponding μ-1,2- bridged squarato complex 4. The magnetic properties are discussed in relation to the structural data.     

A series of thiolato-bridged di- and trinuclear complexes derived from [Tp∗Rh(SPh)2(MeCN)] (Tp∗ = hydrotris(3,5-dimethylpyrazol-1-yl)borate)

Treatment of the Rh(III) complex [Tp∗Rh(SPh)₂(MeCN)] (1) with a series of late transition metal complexes resulted in the formations of thiolate-bridged di- and trinuclear complexes, which include the Rh(III)-Rh(I) complexes, [Tp∗RhCl(μ-SPh)₂Rh(cod)] (2) and [Tp∗RhCl(μ-SPh)₂Rh(PPh₃)₂], the Rh(III)-Pd(II) complexes, [Tp∗RhCl(μ-SPh)₂Pd(η³-C₃H₅)] (4), [{Tp∗Rh(MeCN)}(μ-SPh)₂PdCl₂] (5), and [{Tp∗RhCl(μ-SPh)₂}₂Pd] (6), and the Rh(III)-Pt(II) complex [{Tp∗RhCl(μ-SPh)₂}₂Pt] (7). Early-late transition metal complexes containing the Rh(III)-Re(I) and Rh(III)-Mo(0) metal centers, [Tp∗RhCl(μ-SPh)₂Re(CO)₄] and [{Tp∗Rh(CO)}(μ-SPh)₂Mo(CO)₄] were also prepared from 1. The X-ray analysis has been carried out to confirm the structures for 2, 4, 5, 6, and 7.     

Synthesis, structure and magnetic properties of an oxo-bridged dinuclear iron(III) complex [(TPyA)FFeOFeF(TPyA)](BF4)2 · 0.5MeOH (TPyA = tris(2-pyridylmethyl)amine) containing the FFeOFeF linkage

The reaction of [Fe^II(H₂O)₆](BF₄)₂ with tris(2-pyridylmethyl)amine (TPyA) and triethylamine in methanol under aerobic conditions forms [(TPyA)FFe^IIIOFe^IIIF(TPyA)](BF₄)₂ · 0.5MeOH (1), in which each Fe(III) ion is coordinated to a TPyA and an F⁻ ion as well as an oxo ion (O²⁻) linking two Fe(III) ions. 1 has offset face-to-face π-π interactions between the dimers, and possesses a supramolecular network structure. The magnetic susceptibility of 1 can be fit with g = 2.0, J/k_B = − 153 K (106 cm⁻¹), and θ = − 0.3 K [H = − 2JS_a · S_b]. These indicate that very strong antiferromagnetic interactions occur via the oxo bridge within the Fe(III) dimer and weak antiferromagnetic interactions between the dimers.     

Electronic spectrum and magnetic properties of a dinuclear nickel(II) complex with two nickel(II) ions of C2-twisted octahedral geometry

A dinickel(II) complex [Ni₂(sym-hmp)₂](BPh₄)₂·3.5DMF·0.5(2-PrOH) (1) was synthesized with a dinucleating ligand, 2,6-bis[(2-hydroxyethyl)methylaminomethyl]-4-methyl-phenol [H(sym-hmp)]. The complex 1 (C₉₀H_118.50B₂N_7.50Ni₂O₁₀) crystallized in the triclinic space group with dimensions a = 14.7446(4) Å, b = 15.4244(4) Å, c = 18.7385(6) Å, α = 86.9495(9)°, β = 76.7263(10)°, γ = 86.5370(8)°, and V = 4136.8(2) Å³ and with Z = 2; this is isomorphous to a previous cobalt(II) complex [Co₂(sym-hmp)₂](BPh₄)₂. Single-crystal X-ray analysis revealed a bis(μ-phenoxo)dinickel(II) core structure containing two distorted octahedral nickel(II) ions of C₂ symmetry. The order of the coordination bond lengths is Ni-O(phenoxo) < Ni-O(hydroxy) < Ni-N. The electronic spectrum of 1 was typical for the octahedral nickel(II) complexes, but the axial elongation and the C₂-twist of the equatorial plane were found after a detailed analysis. The bond angles obtained by the electronic spectrum agreed with the crystallographically obtained bond angles within 2.3°. The order of the AOM parameters was e_{σ,O(phenoxo)} > e_{σ,O(hydroxy)} > e_σ,N, which was consistent with the order of the coordination bond lengths. Magnetic susceptibility data for 1 were fitted well with the parameters 2J = −69.7 cm⁻¹, D = 0.00 cm⁻¹, g = 2.17, and TIP = 265 × 10⁻⁶ cm³ mol⁻¹. The result indicates significant antiferromagnetic exchange interaction and negligible zero-field splitting, while the isostructural cobalt(II) complex showed an anisotropic behavior.     

Supported organometallic complexes. Part 27: novel sol-gel processed rhodium(I) complexes: synthesis, characterization, and catalytic reactions in interphases

A novel T-silyl functionalized cationic (COD)(dppp)rhodium(I) complex was sol-gel processed with various amounts of the co-condensing agents MeSi(OMe)₂(CH₂)₆(OMe)₂SiMe and MeSi(OMe)₂(CH₂)₃(C₆H₄)(CH₂)₃(OMe)₂SiMe to give novel stationary phases for ‘Chemistry in Interphases’. The polysiloxane matrices and the integrity of the rhodium(I) complex centers were investigated by means of multinuclear solid-state NMR (¹³C, ²⁹Si, ³¹P) and EXAFS spectroscopies. Dynamic NMR measurements show an increasing mobility of the matrix and the reactive centers with a higher amount of the co-condensing component. The accessibility of the anchored rhodium(I) centers was scrutinized by the metal catalyzed hydrogenation of 1-hexene. All applied xerogels show remarkable activities and selectivities. An enhancement of the activities is achieved when polar solvents are used. SEM micrographs reveal the morphology of the hybrid materials and energy dispersive X-ray spectroscopy (EDX) suggests that the distribution of the elements is in satisfying agreement with the applied composition.     

New rhodium complexes of the tetradentate ligand bis(diacetylmonoxime-imino)propane 1,3 (H2dopn): synthesis and crystal structure of trans-[Rh(Hdopn)Cl]2 and trans-[Rh(Hdopn)(I)2]

The reaction between [Rh(H₂O)₆](ClO₄)₃ and the monoanion Hdopn⁻ (H₂dopn=bis(diacetylmonoxime-imino)propane 1,3=3,9-dimethyl-4,8-diazaundeca-3,8-diene-2,10-dione dioxime) afforded a new dimeric rhodium(II) compound of formula [Rh(Hdopn)(H₂O)]₂(ClO₄)₂ · H₂O (1). Treatment of methanolic solution of 1 with NaX (X=Cl⁻, Br⁻, I⁻) results in the replacement of water with halides in 1, leading to the formation of [Rh(Hdopn)X]₂ rhodium(II) dimers. The X-ray crystal structure of [Rh(Hdopn)Cl]₂ · 0.5H₂O (2) was determined showing a [Rh(II)-Rh(II)] core. Upon the reaction of 1 with NaI carried out in air, [Rh(Hdopn)(I)₂] (3) was isolated and characterized by a single-crystal X-ray diffraction analysis.     

Synthesis, characterization and molecular structure of 1,1′ bis(diphenylphosphino ferrocene)dioxide complex of uranyl nitrate

A 1,1′ bis(diphenylphosphino ferrocene)dioxide complex of uranyl nitrate was synthesized and characterized by IR, ¹H and ³¹P{¹H} NMR spectroscopic and X-ray diffraction methods. The structure of the compound shows that the uranium atom is surrounded by eight oxygen atoms in a hexagonal bi-pyramidal geometry. Two oxygen atoms from 1,1′ bis(diphenylphosphino ferrocene)dioxide ligand and four oxygen atoms from the nitrate groups form a planar hexagon. The two uranyl oxygen atoms occupy the axial position. The 1,1′ bis(diphenylphosphino ferrocene)dioxide ligand acts as a bidentate chelating ligand with a bite angle of 71.56(8)° around the uranium(VI) atom, which is much smaller in value compare to any of the previously reported values (90.1°-154.0°) for this ligand.     

Copper complexes with new oxaaza-pendant-armed macrocyclic ligands: X-ray crystal structure of a macrocyclic copper(II) complex

The synthesis of new oxaaza macrocyclic ligands (2-4) derived from O¹,O⁷-bis(2-formylphenyl)-1,4,7-trioxaheptane and functionalized tris(2-aminoethyl)amine are described. Mononuclear copper(II) complexes were isolated in the reaction of the corresponding macrocyclic ligand and copper(II) perchlorate. The structure of the [Cu(2)](ClO₄)₂ complex was determined by X-ray diffraction analysis. The copper(II) ion is five-coordinated by all N₅ donor atoms, efficiently encapsulated by the amine terminal pendant-arm, with a trigonal-bipyramidal geometry. The complexes are further characterized by UV-Vis, IR and EPR studies. The electronic reflectance spectra evidence that the coordination geometry for the Cu(II) complexes is trigonal-bipyramidal with the ligands 1 and 2 or distorted square-pyramidal with the ligands 3 and 4. The electronic spectra in MeCN solutions are different from those in the solid state, which suggest that some structural modification may occur in solution. The EPR spectrum of powder samples of the copper complex with 2 presents axial symmetry with hyperfine split at g_// with the copper nuclei (I = 3/2), which is characteristic of weakly exchange coupled extended systems. The EPR parameters (g_// = 2.230, A_// = 156 × 10⁻⁴ cm⁻¹ and g_⊥ = 2.085) indicate a d_x²-y² ground state. The EPR spectra of the complexes with ligands 3 and 4 show EPR spectra with a poorly resolved hyperfine structure at g_//. In contrast, the complex with ligand 2 shows no hyperfine split and a line shape which was simulated assuming rhombic g-tensor (g₁ = 2.030, g₂ = 2.115 and g₃ = 2.190).     

The synthesis of the tripodal phosphine CH3C{CH2P(m-CF3C6H4)2}3 and its rhodium coordination chemistry

The new tripodal phosphine CH₃C{CH₂P(m-CF₃C₆H₄)₂}₃, CF₃PPP, was prepared by reacting CH₃C(CH₂Br)₃ with Li⁺P(m-CF₃C₆H₄)₂⁻, the latter being best obtained by adding Li⁺NⁱPr₂⁻ to PH(m-CF₃C₆H₄)₂. The rhodium complexes [RhCl(CO)(CF₃PPP)], [Rh(LL)(CF₃PPP)](CF₃SO₃) (LL = 2 CO or NBD), [RhX₃(CF₃PPP)], [RhX(MeCN)₃(CF₃PPP)](CF₃SO₃)₂ (X = H and Cl), [RhCl₂(MeCN)(CF₃PPP)](CF₃SO₃) and [Rh(MeCN)₃(CF₃PPP)](CF₃SO₃)₃ were prepared and characterized. The X-ray crystal structure of [Rh(NBD)(CF₃PPP)](CF₃SO₃) is reported. The lower oxygen sensitivity of the CF₃PPP rhodium(I) complexes, relative to the corresponding species with the parent ligand CH₃C(CH₂PPh₂)₃, is attributed to the higher effective nuclear charge on the metal centers caused by the presence of the six CF₃ substituents on the terdentate phosphine. A similar effect may be responsible for the easier hydrolysis of the CF₃PPP-containing, cationic rhodium(III) complexes relative to the corresponding compounds of the parent ligand.     

A novel cadmium(II) complex of bipyridine derivative: synthesis,X-ray crystal structure,DNA-binding and antibacterial activities

Abstract

A mononuclear cadmium(II) complex of formula [Cd(5,5′-dmbipy)₂(OAc)₂]·2H₂O (5,5′-dmbipy = 5,5′-dimethyl-2,2′-bipyridine and OAc?=?acetato ligand) has been synthesized and characterized by FT-IR, UV–Vis, ¹H-NMR, elemental analysis and single-crystal X-ray structure analysis. The molecular structure of the complex shows a distorted tetragonal antiprism CdN₄O₄ coordination geometry around the cadmium atom, resulting in coordination by four nitrogen atoms from two 5,5′-dmbipy ligands and four oxygen atoms from two acetate anions. The interaction of this complex to FS-DNA (fish sperm DNA) has also been studied by electronic absorption, fluorescence and gel electrophoresis techniques. Binding constant (K_b), Stern–Volmer constant (K_sv), number of binding sites (n) and bimolecular quenching rate constant (k_q) have been calculated from these spectroscopic data. These results have revealed that the metal complex can bind effectively to FS-DNA via groove binding. The calculated thermodynamic parameters (ΔH°, ΔS° and ΔG°) show that hydrogen bonding and van der Waals forces have an important function in the Cd(II) complex–DNA interaction. The antibacterial effects of the synthesized cadmium complex have also been examined in vitro against standard bacterial strains: one Gram-positive (Staphylococcus aureus, ATCC 25923) and one Gram-negative (Escherichia coli, ATCC 25922) bacteria, using disk diffusion and macro-dilution broth methods. The obtained results show that the Cd(II) complex exhibits a marked antibacterial activity which is significantly better than those observed for its free ligand and metal salt for both Gram-positive and Gram-negative bacteria. However, this metal complex is a more potent antibacterial agent against the Gram-positive than that of the Gram-negative bacteria.

Communicated by Ramaswamy H. Sarma