Syntheses,characterization and biological studies of zinc(II), copper(II) and cobalt(II) complexes with Schiff base ligand derived from 2‐hydroxy‐1‐naphthaldehyde and selenomethionine

Novel zinc(II), copper(II), and cobalt(II) complexes of the Schiff base derived from 2‐hydroxy‐1‐naphthaldehyde and D, L ‐selenomethionine were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, magnetic measurements and powder XRD. The analytical data showed the composition of the metal complex to be ML(H₂O), where L is the Schiff base ligand and M = Co(II), Cu(II) and Zn(II). IR results confirmed the tridentate binding of the Schiff base ligand involving azomethine nitrogen, naphthol oxygen and carboxylato oxygen atoms. ¹H NMR spectral data of lithium salt of the Schiff base ligand [Li(HL)] and ZnL(H₂O) agreed with the proposed structures. The conductivity values of complexes between 12.50 and 15.45 S cm² mol^?1 in DMF suggested the presence of non‐electrolyte species. The powder XRD studies indicated that Co(II) complex is amorphous, whereas Cu(II) and Zn(II) complexes are crystalline. The results of antibacterial and antifungal screening studies indicated that Li(HL) and its metal complexes are active, but CuL(H₂O) is most active among them. Copyright © 2010 John Wiley & Sons, Ltd.     

New dimeric Schiff base quinoline complexes: Synthesis,spectral characterization,electrochemistry and cytotoxicity

A novel Schiff base ligand (H‐DPPMHQ) derived from 2‐hydrazineylquinoline and 1,3‐diphenyl‐1H‐pyrazole‐5‐carbaldehyde and its dimeric complexes with compositions [Cr(DPPMHQ)Cl]₂?2Cl and [M(DPPMHQ)Cl]₂ (where M = Cu(II), Co(II), Ni(II) and Zn(II)) have been synthesized and characterized using physicochemical methods like elemental analysis, magnetic susceptibility and molar conductivity measurements, multispectral techniques and electrochemical studies. The molar conductance data reveal that all metal chelates are non‐electrolytes, except the Cr(III) complex which shows a Λ_M value of 146.82 Ω^?1 cm² mol^?1, indicating that it is a 1:2 electrolyte. Infrared spectral results show that the metal is organized through four nitrogen atoms (azomethine and deprotonated imine groups, pyrazole and quinoline rings) besides chlorine atoms. The NH proton is also displaced during complexation, as indicated by ¹H NMR spectral data. Based on the electron spin resonance and ligand field parameter data, the bonding parameters of these complexes have been calculated. Using Coats–Redfern and Horowitz–Metzger equations, thermodynamic parameters were determined. The spectral data indicate that the dimeric complexes have octahedral geometry around the central metal ions. The cytotoxic activities of all compounds were evaluated towards human breast cancer (MCF‐7) and lung cancer (A549) cell lines.     

9Be and 31P NMR analyses on the influence of imino groups on Be2+ complex stabilities of a series of cyclo‐μ‐imido triphosphate anions

The complexation behaviors of Be²⁺ with cyclo‐μ‐imido triphosphate anions, cP₃O_9?n(NH)_n^3? (n = 1, 2), have been investigated by both ⁹Be and ³¹P NMR techniques at ?2.3 °C in order to clarify the coordination structures of the complexes. The spectra showed that cP₃O_9?n(NH)_n (n = 1, 2) ligands form ML, ML₂, and M₂L complexes with Be²⁺ ions, and the formation of complexes coordinating with nitrogen atoms of the cyclic framework in the ligand molecule has been excluded. These complexation trends are very similar to those of Be²⁺‐cP₃O₆(NH)₃^3? system, which has been reported by us. The peak deconvolution of ⁹Be NMR spectra made these beryllium complexes amenable to stability constant determinations. The stability constants of the complexes increase with an increase in the protonation constants of the ligands as the number of imino groups, which constitute the ligand molecules, is ascended. This increase is primarily attributable to the lower electronegativity of nitrogen atoms than oxygen atoms, which are directly bonded to central phosphorus atoms; moreover, tautomerism equilibrium in the entire of the imidopolyphosphate molecule is also responsible to the higher basicity. ³¹P NMR spectra measured concurrently have verified the formation of the complexes estimated by the ⁹Be NMR measurement. Intrinsic ³¹P NMR chemical shift values of the phosphorus atoms belonging to ligand molecules complexed with Be²⁺ cations have been determined. Not only the protonation constants but also the stability constants of all Be²⁺ complexes increase approximately linearly with an increase in the number of imino groups. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and magnetic properties of μ-phenolato copper (Ⅱ) binuclear complexes with different exogenous bridges

The syntheses and magnetic properties are reported for a series of copper(Ⅱ) complexes prepared from a pentadentate binucleating ligand 2,6-diformyl-4-methylphenol di(benzoyl-hydrazone) (H3L). These complexes incorporate different exogenous ions (X-) into a bridging position to form copper(Ⅱ) binuclear complexes of the formula [Cu2(H2L)X]2+, where X-= Br-(1), Cl-(2), HO-(3), C2H5O-(4) and C3H3N2- (5). The complexes have been characterized with variable temperature magnetic susceptibility (4.2-300 K) and the observed data were fit to those from a modified Bleaney-Bowers equation by least-squares method, giving the exchange integral 2J = -6.2 cm-1 for 1, -76.4 cm-1 for 2, -241.9 cm-1 for 3, -231.1 cm-1 for 4 and -343.8 cm-1 for 5. This suggested that there is an antiferromagnetic interaction between the Cu(Ⅱ) ions and the sequence of the effect of some exogenous bridging ligands on magnetic coupling is corresponding to that in spectrochemical series.     

Synthesis and characterization of novel water-soluble zinc(II) Schiff-base complexes derived from amino acids and salicylaldehyde-5-sulfonates

New water-soluble zinc(II) Schiff-base complexes derived from amino acids (glycine, L-phenylalanine, and L-valine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5-sulfonate) have been synthesized. The complexes were characterized by elemental analysis, IR, electronic, ¹H?NMR, and ¹³C?NMR spectra. In the IR spectra of the complexes, the large difference between the asymmetric ν_as(COO) and symmetric ν_s(COO) carboxylate stretch, Δν(ν_as(COO)–ν_s(COO)) of 199–247?cm^?1, indicates monodentate coordination of the carboxylate group. Spectral data showed that in these complexes the ligand is a tridentate ONO moiety, coordinating to the metal through its phenolic oxygen, imine nitrogen, and carboxyl oxygen.     

Synthesis and characterization of oxodiperoxo complexes of tungsten(VI) with some Mannich base ligands

Six oxodiperoxotungsten(VI) complexes, [WO(O₂)₂L–L] (where L–L?=?morpholinobenzyl benzamide (MBB), piperidinobenzyl benzamide (PBB), piperidinobenzyl urea (PBU), morpholinobenzyl urea (MBU), piperidinobenzyl thiourea (PBTU) and morpholinobenzyl thiourea (MBTU)) have been prepared by stirring WO₃?·?H₂O with excess 30% aqueous (w/v) H₂O₂ and then treating with an ethanolic solution of the Mannich base ligand (L–L). These have been characterized by elemental analysis, conductance and magnetic susceptibility measurements, IR spectra, electronic spectra, ¹H NMR, TGA/DTA and cyclic voltammetric studies. These complexes are non-electrolytes and diamagnetic in nature. The ligands are bound to metal in a bidentate mode through carbonyl oxygen/thiocarbonyl sulphur and the ring nitrogen. The complexes also inhibit the growth of pathogen “Fusarium Spp.” up to 60%. The cyclic voltammograms of the complexes indicate quasi-reversible redox steps involving complexes.     

Synthesis, spectroscopic, and thermal studies of some Hg(II) and Cd(II) coordination compounds of N,N-bis[(E)-3-(phenylprop)-2-enylidene]propanediamine

Some new coordination compounds of cadmium(II) and mercury(II) with N,N-bis[(E)-3-(phenylprop)-2-enylidene]propanediamine (L) as a new bidentate Schiff base ligand with general formula MLX₂ (X = Cl^?, Br^?, I^?, SCN^?, and N₃ ^?) have been prepared. They were characterized by elemental analysis, FT-infrared (FT-IR) and Ultraviolet–Visible spectra, ¹H- and ¹³C-NMR spectra. The reasonable shifts of FT-IR and NMR spectral signals of the complexes with respect to the free ligand confirm well coordination of ligand and anions(X-) in inner sphere coordination mode. The thermal behavior of the complexes from room temperature to 800 °C shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. The results showed that cadmium complexes have no water molecules (neither as lattice nor as coordinated water) and are decomposed in two temperature steps except about cadmium thiocyanate complex that is decomposed in three steps. Final residual contents of cadmium complexes are suggested to be cadmium oxide or sulfide. Mercury complexes were decomposed in three to four temperature steps. Mercury bromide and azide complexes leave out a little amount of mercury oxide in final, while mercury chloride, iodide, and thiocyanate complexes were found to be completely decomposed without any residual matter.     

Cobalt(II) complexes of creatinine

Summary Cobalt(II) complexes of creatinine [Co(creat)₂X₂] (X = Cl, Br, I or NCS) and [Co(creat)₂X₂(H₂O)₂] (X = HCO₂, HOCH₂CO₂ or CNCH₂CO₂) have been prepared. Their i.r. spectra show an increase in (NH) of the cyclic secondary amine group, compared to free ligand (3300 cm^–1), indicating that cyclic nitrogen is involved in coordination. The thiocyanate group coordinates through nitrogen and carboxylates coordinate as univalent unidentate ligands. The electronic spectra and magnetic moments suggest a d⁷ configuration for cobalt: a tetrahedral geometry (4.4 B.M.) for halide and thiocyanate complexes, and an octahedral geometry (5.0 B.M.) for the carboxylate complexes. On heating, the ligand moiety is lost and the respective cobalt halide or cobalt carboxylate is formed, which is converted finally into Co₃O₄. There is a correlation between the high intensity electronic transitions and the polarographic half-wave potentials.     

Intra- and intermolecular hydrogen bonding in formohydroxamic acid complexes with water and ammonia: infrared matrix isolation and theoretical study

The complexes of formohydroxamic acid with water and ammonia have been studied using FTIR matrix isolation spectroscopy and MP2 calculations with a 6-311++G(2d,2p) basis set. The analysis of the experimental spectra of the HCONHOH/H₂O(NH₃)/Ar matrixes indicates formation of strongly hydrogen-bonded complexes in which the NH group of formohydroxamic acid acts as a proton donor toward the oxygen atom of water or the nitrogen atom of ammonia. The NH stretching vibration of formohydroxamic acid exhibits 150 cm⁻¹ red shift in the complex with water and 443 cm⁻¹ red shift in the complex with ammonia as compared to the NH stretch of the HCONHOH monomer. The theoretical calculations indicate stability of five isomers for the water complex and three isomers for the ammonia complex. The most stable are the cyclic structures in which the water or ammonia molecules are inserted within the intramolecular hydrogen bond of the formohydroxamic acid molecule and act as proton donors for the CO group and proton acceptors for the OH group of the formohydroxamic acid molecule. In spite of their stability the cyclic structures have not been observed in the matrixes which indicates high energy barrier for their formation, the reaction of complex formation is under kinetic and not thermodynamic control.     

Magnesium Cyanide or Isocyanide?

Preference for the binding mode of the CN^? ligand to Mg (Mg?CN vs. Mg?NC) is investigated. A monomeric Mg complex with a terminal CN ligand was prepared using the dipyrromethene ligand ^MesDPM which successfully blocks dimerization. While reaction of (^MesDPM)MgN(SiMe₃)₂ with Me₃SiCN gave the coordination complex (^MesDPM)MgN(SiMe₃)₂?NCSiMe₃, reaction with (^MesDPM)Mg(nBu) led to (^MesDPM)MgNC?(THF)₂. A Mg?NC/Mg?CN ratio of ≈95:5 was established by crystal‐structure determination and DFT calculations. IR studies show absorbances for CN stretching at 2085 cm^?1 (Mg?NC) and 2162 cm^?1 (Mg?CN) as confirmed by ¹³C labeling. In solution and in the solid state, the CN ligand rotates within the pocket. The calculated isomerization barrier is only 12.0 kcal mol^?1 and the ¹³C NMR signal for CN decoalesces at ?85 °C (Mg?NC: 175.9 ppm, Mg?CN: 144.3 ppm). Experiment and theory both indicate that Mg complexes with the CN^? ligand should not be named cyanides but are more properly defined as isocyanides.     

Coordination complexes of rare earth metals with hydrazine and isomeric acetamidobenzoates as ligands– spectral,thermal and kinetic studies

The isomeric acetamido benzoic acids (abbreviated as acambH) on reaction with hydrazine hydrate and lanthanides, La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺ and Gd³⁺ form complexes of formulae, [Ln{x-C₆H₄(CH₃CONH)}₃(N₂H₄)] where x = 2 (or) 3 (or) 4, at pH 3–4.5 in (1:1) aqueous ethanolic medium, which are insoluble in water and organic solvents. They are characterized by using elemental analysis, IR, UV, ¹³C, ¹H NMR and mass spectroscopic, XRD, SEM-EDAX, thermal and conductance studies. The difference between IR bands of v_{C=O asym} (acid) and v_{C=O sym}(acid) range, 122–166 cm^?1 supports the bidental coordination of carboxylate ions to metal. v_N-N values of 955 to 980 cm^?1, substantiate bridging bidentate coordination of hydrazine to metal. v_C=O of amide group 1632 to1709 cm^?1 indicates its non-coordination with metal. The thermal studies reveal that complexes undergo dehydrazination between 52 and 180 °C and exothermic degradation into phthalate intermediate between 172 and 496 °C and further degradation to form microsized metal oxide around 600 °C. The magnetic susceptibility measurements indicated that the presence of metals in the same electronic state and electronic spectral assignments suggested that the coordination number is eight for the complexes. The conductance measurement results in DMSO medium indicated that the complexes are neutral. The ¹³C – NMR, ¹H- NMR and the LC-Mass techniques substantiated the composition of the complexes.     

A novel vic-dioxime ligand and its Ni(II), Cu(II) and Co(II) complexes containing calix[4]pyrrole moiety: synthesis, characterization and redox properties

A new calix[4]pyrrole functionalized vic-dioxime, 3-(4-methyl-9,9,14,14,19,19-hexaethylcalix[4]pyrrole)benzoaminoglyoxime (LH₂) was synthesized from anti-chloroglyoxime and 3-aminophenyl-calix[4]pyrrole at room temperature. The mononuclear complexes {nickel(II), copper(II) and cobalt(II)} of this vic-dioxime ligand were prepared and their structures were confirmed by elemental analysis, IR and UV–Vis spectrophotometry, magnetic susceptibility; the MS, ¹H and ¹³C NMR spectra of the LH₂ ligand and its Ni(II) complex were also recorded. The experimental results indicated that the ligand:metal ratio was 2:1 in the cases of Ni(II), Cu(II) and Co(II) complexes as is with most vic-dioximes. Electrochemical properties of the ligand, and its complexes were investigated in DMSO solution by cyclic voltammetry at 200?mV?s^?1 scan rate.     

Synthesis and characterization of an unsymmetric salicylaldimine ligand derived from 1-(2-Aminoethyl) piperazine and investigation of its analytical properties for the extraction and preconcentratoion of some divalent cations

The synthetic, structural, spectroscopic and analytical properties of steric hindered Schiff-base ligand [N-(3,5-di-tert-butylsalicylaldimine)-1-(2-Aminoethyl) piperazine (HL)] and its mononuclear Cu(II), Co(II) and Ni(II) complexes are described. The new unsymmetric steric hindered Schiff base ligand containing a donor set of NONO was prepared by the reaction of 1-(2-Aminoethyl) piperazine with 3,5-di-tert-butylsalicylaldehyde. Certain metal complexes of this ligand were synthesized by treating an ethanolic solution of the ligand with an equimolar amount of metal salts. The ligand and its metal complexes were characterized by FT-IR, UV-Vis, ¹H NMR, elemental analysis, molar conductivity and magnetic susceptibility techniques. The reaction of this ligand in a 1:2 mole ratio with metal acetate afforded mononuclear metal complexes. The molar conductivity (??_M) values of the metal complexes of Ni(II), Co(II) and Cu(II) were in the range of 6.4 to 9.8 ??^?1 cm² mol^?1 at room temperature. Preconcentration and separation of Cu²⁺ from aqueous solution using N-(3,5-di-tert-butylsalicylaldimine)-1-(2-Aminoethyl) piperazine (HL) as a new extractant were studied. The extraction experiments were carried out at various pHs. While Cu²⁺ showed the highest extractability and selectivity at pH 7.0, extractions of Co²⁺ and Ni²⁺ were unsuccessful due to precipitate formation.     

Osmium(II)-Phthalocyanine: Darstellung und Eigenschaften von Di(acido)phthalocyaninatoosmaten(II)

Osmium(II) Phthalocyanines: Preparation and Properties of Di(acido)phthalocyaninatoosmates(II) “H[Os(X)₂Pc^2?]” (X = Br, Cl) reacts in basic medium or in the melt with (ⁿBu₄N)X forming less stable, diamagnetic, darkgreen (ⁿBu₄N)₂[Os(X)₂Pc^2?]. Similar dicyano and diimidazolido(Im) complexes are formed by the reaction of “H[Os(Cl)₂Pc^2?]” with excess ligand in the presence of [BH₄]^?. The cyclic voltammograms show up to three quasireversible redoxprocesses: E_1/2(I) = 0.13 V (X = CN), ?0.03 V (Im), ?0.13 V (Br) resp. ?0.18 V (Cl) is metal directed (Os^II/III), E_1/2(II) = 0.69 V (Cl), 0.71 V (Br), 0.83 V (CN), 1.02 V (Im) is ligand directed (Pc^2?/?) and E_1/2(III) = 1.17 V (Cl) resp. 1.23 V (Br) is again metal directed (Os^III/IV). Between the typical “B” (～16.2 kK) and “Q” (～29.4 kK), “N regions” (～34.1 kK) up to seven strong “extra bands” of the phthalocyanine dianion (Pc^2?) are observed in the uv-vis spectrum. Within the row CN > Im > Br > Cl, most of the bands are shifted slightly, the “extra bands” considerably more to lower energy in correlation with E_1/2(I). The vibrational spectra are typical for the Pc^2? ligand with D_4h symmetry. M.i.r. bands at 514, 909, 1 173 and 1 331 cm^?1 are specific for hexa-coordinated low spin Os^II phthalocyanines. In the resonance Raman (r.r.) spectra polarized, depolarized or anomalously polarized deformation and stretching vibrations of the Pc^2? ligand will be selectively enhanced, if the excitation frequency coincides with “extra bands”. With excitation at ～19.5 kK the intensity of the symmetrical Os? X stretching vibration at 295 cm^?1 (X = Cl), 252 cm^?1 (X = Im) and 181 cm^?1 (X = Br) is r.r. enhanced, too. The asymmetrical Os? X stretching vibration is observed in the f.i.r. spectrum at 345 cm^?1 (X = CN), 274 cm^?1 (X = Cl), 261 cm^?1 (X = Im) and 200 cm^?1 (X = Br).     

Thermochemical study of the stepwise protonation of 1,10-diaza-4,7-dithiadecane,and its complex formation with copper(II) and nickel(II) ions in aqueous solution

The behaviour of 1,10-diaza-4,7-dithiadecane (2,2,2-NSSN) in aqueous solution in equilibria with protons, Cu²⁺ or Ni²⁺ ions has been investigated potentiometrically and calorimetrically. The protonation constants for the ligand, and the stability constants for its complexes at 25°C in 0.5 mole dm^?3 (K)NO₃ are reported, together with the corresponding thermodynamic parameters ΔG, ΔH and ΔS. The results are compared with those for 1-aza-4-thiapentane and 1,7-diaza-4-thiaheptane. The ligand 2,2,2-NSSN forms complexes of formula ML²⁺ and MHL³⁺ with both Cu²⁺ and Ni²⁺. It is found that in the non-protonated 1:1 complexes the ligand acts as a tetradentate. In the CuHL³⁺ complex, the ligand is bound through one nitrogen and two sulphur donors, whereas in the NiHL³⁺ complex the ligand is probably bound through only one nitrogen and one sulphur donor. Explanations are suggested.     

Synthesis,characterization and in vitro biological activity of cobalt(II), copper(II) and zinc(II) Schiff base complexes derived from salicylaldehyde and D,L‐selenomethionine

New cobalt(II), copper(II) and zinc(II) complexes of Schiff base derived from D,L ‐selenomethionine and salicylaldehyde were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, magnetic measurements and biological activity. The analytical data showed that the Schiff base ligand acts as tridentate towards divalent metal ions (cobalt, copper, zinc) via the azomethine‐N, carboxylate oxygen and phenolato oxygen by a stoichiometric reaction of M:L (1:1) to form metal complexes [ML(H₂O)], where L is the Schiff base ligand derived from D,L ‐selenomethionine and salicylaldehyde and M = Co(II), Cu(II) and Zn(II). ¹H NMR spectral data of the ligand and Zn(II) complex agree with proposed structures. The conductivity values between 12.87 and 15.63 S cm² mol^?1 in DMF imply the presence of non‐electrolyte species. Antibacterial and antifungal results indicate that the metal complexes are more active than the ligand. Copyright © 2010 John Wiley & Sons, Ltd.     

Organometallic ligands : II. The coordination chemistry of 1-[(dimethylamino)-methyl]-2-(diphenylphosphino)ferrocene

Complexes of the organometallic ligand (h⁵-C₅H₅)Fe[(h⁵-C₅H₃)(1-CH₂NMe₂)(2-PPh₂)] (FcCNP) have been prepared with the carbonyls of chromium, molybdenum, tungsten, iron, and cobalt and with borane. With the Group VIB metals, the ligand forms complexes of the type (FcCNP)M(CO)₄ in which the FcCNP ligand is chelating. However, in the case of (FcCNP)Fe(CO)₄ and [(FcCNP)₂Co(CO)₃]BPh₄ the ligand is monodentate, the phosphorus acting as the donor atom. Infrared and NMR data were used to establish the mode of coordination in each case. The electrochemistry of the Group VIB metal carbonyl complexes has been investigated, the chromium complex being of particular interest. The cyclic voltammogram of (FcCNP)Cr(CO)₄ consists of two, reversible, one electron redox waves at E_{peak, anodic} + 0.54 V and + 0.96 V (vs. SCE in CH₂Cl₂), and a third, irreversible wave at E_{peak, anodic} + 1.47 V. At + 0.54 V the solution color changed from yellow to orange and the v(CO) bands shifted from 2011 w, 1891 s, and 1831 s (cm^?1) in the neutral complex to 2080 m, 2000 s, and 1970 s (cm^?1) in the singly oxidized species. At + 0.96 V, the color changed further to blue-green, but no additional shift in v(CO) was observed. On the basis of this information, it is concluded that the first redox wave represents the process Cr⁰ → Cr⁺ and the second wave Fe²⁺ → Fe³⁺. Other aspects of the electrochemistry of the Group VIB metal carbonyl complexes are discussed.     

Lanthanide complexes derived from hexadentate macrocyclic ligand: Synthesis,spectroscopic and thermal investigation

The lanthanide complexes derived from (3,5,13,15-tetramethyl 2,6,12,16,21-22-hexaazatricyclo[15.3.I^1-17I^7-11]cosa-1(21),2,5,7,9,11(22),12,15,17,19-decane) were synthesized. The complexes were found to have general composition [Ln(L)X₂·H₂O]X, where Ln = La³⁺, Ce³⁺, Nd³⁺, Sm³⁺ and Eu³⁺ and X = NO₃^? and Cl^?. The ligand was characterized by elemental analyses, IR, Mass, and ¹H NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral techniques and thermal studies. The ligand acts as a hexadentate and coordinates through four nitrogen atoms of azomethine groups and two nitrogen of pyridine ring. The lanthanum complexes are diamagnetic while the other Ln(III) complexes are paramagnetic. The spectral parameters i.e. nephelauxetic ratio (β), covalency factor (b^1/2), Sinha parameter (δ%) and covalency angular overlap parameter (η) have been calculated from absorption spectra of Nd(III) and Sm(III) complexes. These parameters suggest the metal–ligand covalent bonding. In the present study, the complexes were found to have coordination number nine.