Synthesis,characterization and arsenate binding events of new mononuclear copper(II) complexes

Two new mononuclear copper (II) complexes [Cu(L)(H₂O)Cl] (1) and [Cu(L)(H₂O)(SCN)] (2) (HL = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol) have been synthesized and characterized in order to investigate their binding interaction with arsenate ions. Complexes 1 and 2 were synthesized by performing reaction of CuCl₂·2H₂O or CuCl₂·2H₂O/NH₄SCN, respectively, with HL using Et₃N as mild base in MeOH solution at room temperature, and characterized by employing a number of analytical techniques, for example, elemental analysis, molar electrical conductivity, FTIR, UV–Vis and mass spectrometry. Their structures, optimized at DFT/B3LYP/6-311G level, show that the copper atom in 1 and 2 exhibits a distorted square pyramidal geometry. In H₂O/MeOH (3:1; v/v) solution, complexes 1 and 2 were examined for their binding affinity towards arsenate ions. The UV–Vis spectroscopic results specify that the arsenate group binds with 1 and 2 in 1:1 M ratio. The UV–Vis titration data were successfully utilized to calculate the binding constants of arsenate-bound Cu(II) complexes, and the values are found to be 1.723 × 10⁴ M^?1 and 2.161 × 10⁴ M^?1, corresponding to 1/AsO₄^3? and 2/AsO₄^3? assemblies, respectively.     

Synthesis,Crystal Structures and Magnetic Properties of Three New Polynuclear Cu(II) Complexes Based on the Methoxybenzoate Isomers

In this paper, self-assembly reactions of copper(II) ions, methoxybenzoate isomers and 2,2′-bipyridine yield two copper-oxygen polynuclear complexes: [Cu₂(bpy)₂(2-C₈H₇O₃)₃]·(2-C₈H₇O₃)·14H₂O 1, [Cu₄(bpy)₄(H₂O)(OH)₄]·4(3-C₈H₇O₃)·17H₂O 2, and a simple mononuclear complex [Cu(bpy)(H₂O)(4-C₈H₇O₃)₂] 3. (bpy = 2,2′-bipyridine, C₈H₇O₃ = methoxybenzoate ion). Single crystal X-ray diffraction analyses reval that compound 1 is a dinuclear copper(II) complex which bridged by three carboxylate groups, and 2 presents a discrete step-like tetra-nuclear copper Cu₄O₄ core. Compound 3 shows a square pyramidal mononuclear geometry. The magnetic susceptibility of complex 1 measured from 2 to 300 K, revealed an antiferromagnetic interaction between the Cu(II) ions. Furthermore, the results about IR spectra and thermal analyses were discussed.     

Versatility of copper(II) coordination compounds with 2,3-bis(2-pyridyl)pyrazine mediated by temperature,solvents and anions choice

Tuning reaction temperatures as well as the variation in starting copper salts and solvents led to the formation of a new series of Cu(II) coordination compounds with 2,3-bis(2-pyridyl)pyrazine (dpp): a mononuclear [Cu(acac)(dpp)(NO₃)] (1) complex, two dinuclear [Cu₂(acac)₂(dpp)(NO₃)(H₂O)]NO₃ (2) and [Cu₂(Hdpp)₂(ox)(Cl)₂(H₂O)₂]Cl₂·6(H₂O) (4) complexes, and four coordination polymers {[Cu₄(dpp)₂(ox)(Cl)₆]}_n (3), {[Cu₄(dpp)₂(ox)(NO₃)₆(H₂O)₂]∙1.2(H₂O)}_n (5), {[Cu(dpp)(NO₃)](NO₃)·(H₂O)}_n (6) and {[Cu(dpp)(SO₄)(H₂O)₂]}_n (7), where acac⁻ = acetylacetonate, ox²⁻ = oxalate. Remarkably, the treatment of Cu(II) chloride dihydrate with dpp in methanol solution led to an unusual in situ condensation of dpp with acac⁻ to produce [Cu₂(acdpp)₂(Cl)₄]·2(MeOH) (8). The structure of 1 consists of neutral, mononuclear [Cu(acac)(dpp)(NO₃)] units with acac⁻ and dpp acting as bidentate ligands. In 2, the dpp ligand coordinates in a bis-chelating mode to two Cu(II) ions and bridges them into a dimeric entity, whereas an oxalate linker joins [Cu(Hdpp)(Cl)₂(H₂O)]⁺ units into a dimer in 4. Compounds 3, 5, 6 and 7 are 1D chain coordination polymers, which incorporate two symmetry independent metal centers and different bridging ligands: Hdpp⁺ as a protonated cationic or dpp as a neutral chelating ligand and oxalate, Cl⁻ anions or sulfate di-anions as bridging ligands. Magnetic studies were performed on samples 1 and 2, and the analysis reveals a very weak magnetic exchange coupling mediated via the dpp ligand.     

A series of novel 1D coordination polymers constructed from metal–quinolone complex fragments linked by aromatic dicarboxylate ligands

Self-assembly of quinolones with metal salts in the presence of aromatic dicarboxylate ligands affords a series of novel 1D metal–quinolone complexes, namely [Mn(Hppa)(oba)]·3H₂O (1), [Co(Hppa)(oba)]·3.25H₂O (2), [Zn(Hppa)(sdba)]·1.5H₂O (3), [Mn(Hcf)(bpda)(H₂O)]·2H₂O (4), [Mn(Hppa)₂(bpdc)] (5) and [Mn(Hlome)₂(bpdc)]·4H₂O (6) (Hppa = Pipemidic acid, Hcf = ciprofloxacin, Hlome = lomefloxacin). The structures of compounds 1–3 consist of novel polymeric chains spanning two different directions, which display an intriguing 1D → 3D inclined polycatenation of supramolecular ladders. Compound 4 exhibits a chain compound formed from the interconnection of [Mn₂(Hcf)₂(μ-CO₂)₂] dimers with bpda ligands. Compounds 5 and 6 are similar chain compounds constructed from [Mn(Hppa)₂] (or [Mn(Hlome)₂]) fragments linked by bpdc ligands. The magnetic properties of 4 have been studied, which indicate the existence of antiferromagnetic interactions. Furthermore, the luminescent properties of compound 3 are discussed.     

Synthesis and characterisation of mono- and dinuclear diethyldithiocarbamatonickel(II) organochalcogenide complexes

The reaction of Ni(dtc)(PR₃)Cl (dtc=diethyldithiocarbamate, R=Ph or Bu) with HSC₆H₄Cl-4 or HSCH₂C₆H₄Cl-4 and Et₃N gave two types of complex. For PPh₃, the products were [Ni(dtc)(μ-SC₆H₄Cl-4)]₂ (1) and [Ni(dtc)(μ-SCH₂C₆H₄Cl-4)]₂ (2); whilst PBu₃ gave Ni(dtc)(PBu₃)(SC₆H₄Cl-4) (3). The structure of freshly prepared 3 was determined to be monomeric, as indicated by X-ray diffraction studies. However, at room temperature in solution, 3 was observed to slowly convert to 1. Structural identification of 1 and 2 and similar dimers, and structural identification of 3 and analogous monomers, were investigated by mass spectrometry. Electron impact mass spectrometry (EIMS) failed to confirm the proposed structures due to extensive decomposition in the mass spectrometer. In the electron impact (EI) mode, all complexes invariably decomposed to Ni(dtc)₂; on the other hand, fast atom bombardment (FAB) ionisation gave the expected molecular ions for all compounds.     

Diverse topologies of three cobalt(II) coordination polymers constructed from flexible bis(benzimidazole) and dicarboxylate ligands

Three cobalt(II) coordination polymers {[Co(L1)(nda)(H₂O)₂]·2H₂O} _n (1), [Co(L2)(tbi)(H₂O)] _n (2) and [Co(L2)(bpdc)(H₂O)] _n (3) (L1 = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)-2-propanol, L2 = 1,3-bis(benzimidazol-1-yl)-2-propanol, H₂nda = 2,6-naphthalenedicarboxylic acid, H₂tbi = 5-tert-butyl isophthalic acid and H₂bpdc = 4,4′-biphenyldicarboxylic acid) were synthesized and characterized by physicochemical and spectroscopic methods. Complex 1 exhibits a 1D loop-like structure, which is further extended into a 3D 3,3,4T31 network through two O–H···O hydrogen bonding interactions. Complex 2 displays a 1D ladder-like chain, arranged into a 2D supramolecular network with 3,3,4L34 topology via classical O–H···O hydrogen bonding interactions, whereas complex 3 features a 2D 3,4L13 layer structure and further assembles into a 3D framework with a twofold interpenetrating sqc65 topology through O–H···O hydrogen bonding interactions. The fluorescence and catalytic properties of these complexes for the degradation of Congo red in a Fenton-like process have been investigated.     

Kinetics and mechanism of benzene oxidation by peroxymonosulfate catalyzed with a binuclear manganese(IV) complex in the presence of oxalic acid

It is established that Oxone (peroxymonosulfate, 2KHSO₅ · KHSO₄ · K₂SO₄) oxidizes benzene to p-quinone very efficiently and selectively in a homogeneous solution in aqueous acetonitrile in the presence of a catalyst, i.e., dimeric manganese(IV) complex [LMn(O)₃MnL](PF₆)₂ where L is 1,4,7-trimethyl-1,4,7-triazacyclononane, and a cocatalyst, i.e., oxalic acid. The dependences of the maximum rate of quinone accumulation on the initial concentrations of reagents are studied. It is proposed that benzene is oxidized by the manganyl particle containing the Mn(V)=O fragment that forms upon the reaction of the reduced form of the starting dimeric manganese complex with Oxone.     

Platinum complexes bearing 2,2′-dipyridylamine ligand

The replacement of the iodide ligands in the complex [PtI₂(dpa)] (1) (dpa is 2,2′-dipyridylamine) by silver triflate in acetonitrile afforded the compound [Pt(dpa)(MeCN)₂](SO₃CF₃)₂ (2). Homoleptic complexes [Pt(dpa)₂](X)₂ (3·(X)₂) were synthesized by the treatment of [PtI₂(dpa)] (1) with 2,2′-dipyridylamine in the presence of silver salts AgX in methanol (X = NO₃) or acetonitrile (X = SO₃CF₃). The deprotonation of the complex [3](SO₃CF₃)₂ to give the homoleptic complex [Pt(dpa-H)₂] (4) was performed by two methods, e.g., by the treatment of [3](SO₃CF₃)₂ with 2 equiv. of NaOH in methanol or by the addition of excess Et₃N to a suspension of [3](SO₃CF₃)₂ in methanol. The structures of compounds 1–4 were established by elemental analyses, high resolution electrospray ionization mass spectrometry, IR and NMR spectroscopy; the crystal structure of complexes [2](SO₃CF₃)₂, [3](NO₃)₂·H₂O, [3](SO₃CF₃)₂·2H₂O, and 4 were determined by single-crystal X-ray diffraction.     

Synthesis and Structure of Copper(II) Nitrate Complexes with 2, 6‐Bis(pyrazolyl)pyridine

Three mononuclear copper(II) complexes of copper nitrate with 2, 6‐bis(pyrazol‐1‐yl)pyridine ( bPzPy ) and 2, 6‐bis(3′,5′‐dimethylpyrazol‐1‐yl)pyridine ( bdmPzPy ), [Cu(bPzPy)(NO₃)₂] ( 1 ), [Cu(bPzPy)(H₂O)(NO₃)₂] ( 2 ) and [Cu(bdmPzPy)(NO₃)₂] ( 3 ) were synthesized by the reaction of copper nitrate with the ligand in ethanol solution. The complexes have been characterized through analytical, spectroscopic and EPR measurements. Single crystal X‐ray structure analysis of complexes 1 and 2 revealed a five‐coordinate copper atom in 1 , whereas 2 contains a six‐coordinate (4+2) Cu^II ion with molecular units acting as supramolecular nodes. These neutral nodes are connected through O–H ··· O(nitrate) hydrogen bonds to give couples of parallel linear strips assembled in 1D‐chains in a zipper‐like motif.     

Nitrosolates and related compounds—IX: Coordination compounds of divalent copper,nickel and cobalt with nitroacetate(2−) ions as chelating ligands. Crystal and molecular structure of potassium bis[nitroacetato(2−)]cuprate(II)-water (1/1)

The syntheses of K₂[Cu(nac)₂]·H₂O (4), [Cu(nac)(N-N)(H₂O)]·H₂O (N-N = bpy, phen; 5,6) and [M(nac)(N-N)₂]·xH₂O (M = Ni, Co; 7–10) with nitroacetate(2?) ions (nac^2?) as chelating ligands are described.The structure of 4 has been determined by single crystal X-ray diffraction and contains square planar [Cu(nac)₂]^2? units in which the nitro and carboxyl groups of the two chelate ligands are in cis positions. Two of the units form a centrosymmetric dimer with a four-membered CuOCu“O”-ring, the dimers being connected by exo-oxygens of the ligands into two-dimensional layers. The water molecules and the potassium ions are arranged between the layers; there are two kinds of potassium ions with distorted (1+4+1) and (2+4+3) coordinations respectively.     

Correlations between structure and magnetism of three N,N′-ethylene-bis(3-methoxysalicylideneimine) gadolinium complexes

Three Salen-like gadolinium complexes, namely, mononuclear (4f) complex [{H₂L}Gd(NO₃)₃] (1), heterodinuclear (3d–4f) complex [{LCu}Gd(NO₃)₃]·0.25H₂O (2) and dimeric heterotrinuclear (3d–4f–3d′) complex [{LCu}Gd(H₂O)₃{Fe(CN)₆}]₂·6H₂O (3) [H₂L = N,N′-ethylene-bis(3-methoxysalicylideneimine)] have been synthesized by stepwise reactions. X-ray diffraction analysis reveals that 1 is of a discrete structure in which H₂L coordinates to gadolinium ion through O₂O₂ moiety. Then, addition of Cu(Ac)₂·H₂O to the mononuclear lanthanide complex yields expected heterodinuclear (3d–4f) complexes [{LCu}Gd(NO₃)₃]. 3 features a unique 1D ladder-like topology structure through the intermolecular double links of Cu–N bonds. The measurement of variable-temperature magnetic susceptibility reveals that complex 1 exhibits antiferromagnetic interaction while 2 and 3 exhibit ferromagnetic interaction between spin carriers. The correlations between the structure and magnetism are described and discussed.     

Two new 2D copper(II) complexes constructed from a flexible bis-pyridyl-bis-amide ligand and two aromatic tricarboxylates: syntheses, crystal structures, fluorescence, and electrochemical properties

Two new 2D metal-organic complexes, namely [Cu(3-dpyb)(1,2,4-HBTC)(H₂O)]·H₂O (1) and [Cu₃(3-dpyb)₃(SIP)₂(H₂O)₈]·6H₂O (2) [3-dpyb?=?N,N??-bis(3-pyridinecarboxamide)-1,4-butane, 1,2,4-H₃BTC?=?1,2,4-benzenetricarboxylic acid, H₃SIP?=?5-sulfoisophthalic acid], have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, TG, and single crystal X-ray diffraction analyses. Single crystal X-ray analyses reveal that the two Cu(II) complexes show different 2D coordination networks, the 4-connected (4⁴·6²) topology for complex 1 and the (4·6²)₂(4²·6²·8²) topology for complex 2. In the 2D layers of complexes 1 and 2, the 3-dpyb ligands adopt a typical ?? ₂-bridging mode (via ligation of two pyridyl nitrogen atoms), while 1,2,4-HBTC and SIP serve as a linear spacer and a ??V??-like linker, respectively, to connect the adjacent Cu(II) centers. The adjacent 2D layers are extended to 3D supramolecular networks via hydrogen-bonding interactions. The fluorescence properties of both complexes and electrochemical properties of complex 2 have also been investigated. The complex 2 bulk-modified carbon paste electrode (2-CPE) displayed a one-electron redox wave in potential range of 600?C200?mV in 1?M H₂SO₄ aqueous solution, and 2-CPE showed good electrocatalytic activity toward the reduction of nitrite.     

Synthesis, crystal structures and antibacterial activities of schiff base ligand and its cobalt(II) complex

The Schiff base ligand, HL · 0.5C₂H₅OH (HL = methyl N-[(4-chlorophenyl)(3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-ylindene)methyl]valine), was derived from condensation of 1-phenyl-3-methyl-4-(p-chlorbenzyl)-5-pyrazolone with L-valine methyl ester in a 1: 1 molar ratio in methanol, ether and isopropanol solution. Reaction of ligand with Co(ClO₄)₂ · 6H₂O (in a 2: 1 molar ratio) in methanol solution afforded a mononuclear cobalt(II) complex, [Co(L)₂] (I). Molecular structures of HL · 0.5C₂H₅OH and complex I were characterized by elemental analysis, IR and single crystal X-ray diffraction analysis. The enamine-keto form of the ligand has turned to imine form in complex I. Each Co(II) center in complex I is in a octahedral N₂O₄ coordination sphere. Both the Schiff base ligand and its Co(II) complex have been tested in vitro with agar dilution method to evaluate their antibacterial activity against bacteria Escherichia coli and Staphylococcus aureus. It has been found that they have higher activity against Escherichia coli than Staphylococcus aureus, and complex I has higher activity than HL · 0.5C₂H₅OH against the same bacteria.     

Structure,synthesis, and thermal properties of trans-[Ru(NO)(NH3)4(SO4)]NO3·H2O

In treatment of trans-[Ru(NO)(NH₃)₄(OH)]Cl₂ with concentrated sulfuric acid on heating trans-[Ru(NO)(NH₃)₄(SO₄)](HSO₄)·H₂O (I) is obtained with a yield close to quantitative. In the interaction of the saturated solution of I with a saturated NaNO₃ solution a trans-[Ru(NO)(NH₃)₄(SO₄)]NO₃·H₂O (II) precipitate forms whose structure is determined by single crystal XRD: space group P2₁2₁2₁, a = 6.8406(3) Å, b = 12.6581(5) Å, c = 13.3291(5) Å. A monodentately coordinated sulfate ion is in the trans-position to the nitroso group. Compound II is characterized by IR spectroscopy, powder XRD, and diffuse reflectance spectroscopy. The process of its thermolysis is studied; by differential scanning calorimetry the thermal effect of the dehydration reaction occurring on heating to 120°C (ΔH = 58.9 ± 1.5 kJ/mol) is estimated. The final product of the thermolysis of II is a mixture of Ru and RuO₂.     

Mixed-ligand platinum(IV) complexes with amino acids and cytosine

Complex formation in platinum(IV)-cytosine-amino acid (glycine, α-alanine, lysine, or histidine) systems is studied using pH titration. Stability constants for 1:1:1 stoichiometry of complexes are determined. The stability of the mixed-ligand complexes varies in the following order: Lys < Ala < Gly < His. Reactions of aqueous solutions yields the following complexes: Pt(Cyt)(Gly^?)Cl₃ · 3H₂O (I), pt(Cyt)(Ala^?)Cl₃ · 3H₂O (II), Pt(Cyt)(Hist)Cl₄ · 2H₂O (III), and Pt(Cyt)(Lys)Cl₄ · 2H₂O (IV). ¹³C NMR, IR, and XPS spectra show that glycine and alanine are complexed via amino and carboxy groups, lysine via its α-amino group exclusively, and histidine via its amino group and heterocyclic N3 atom. Cytosine in these complexes is bidentate (it is complexed via C=O oxygen and N3 heterocyclic atoms).     

Comprehensive comparison between the reaction of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>'-cyclohexane-1,2-diylidene-bis(4-methoxybenzoylhydrazide) with mercury(II) and copper(II) ions. Synthesis,structure, and kinetics of complex formation

Comprehensive comparison between the reaction of N,N'-cyclohexane-1,2-diylidene-bis(4-methoxybenzoylhydrazide) (CHMBH) with HgCl₂ and Cu(NO₃)₂ · 2.5H₂O salts have been investigated, including the synthesis, structure and kinetic of complex formation. The reactions of CHMBH with HgCl₂ or Cu(NO₃)₂ · 2.5H₂O at the same synthetic conditions have been shown to produce completely different type of complexes: [Hg(CHMBH)Cl₂] · CH₃CN (I) and [Cu₃(μ₃-OH)(CTMB)₃(NO₃)₂(CH₃CN)₂] · 5CH₃CN · H₂O (II) (CTMB = cyclohexotriazole-3-(4-methoxybenzamide)). The prepared compounds were characterized using different techniques (NMR, IR, UV-Vis and mass spectroscopies, microelemental analysis, thermogravimetry as well as X-ray powder differection and X-ray single crystal crystallography for I (CIF file CCDC no. 1503398). X-ray crystallography shows that the isolated product of I is a mononuclear complex which contains the [Hg(CHMBH)]²⁺ core. While, the isolated product of II was a trinuclear Cu(II) cluster [Cu₃(μ₃-OH)(CTMB)₃(NO₃)₂(CH₃CN)₂] · 5CH₃CN · H₂O which contains three differently coordinated copper sites. Kinetic studies on the formation of I have been also investigated and compared with that of II. In case of I, the reaction was so slow and exhibits a first-order dependence on the concentration of metal salt and a first-order dependence on the concentration of CHMBH. While in II, the study shows that the reaction is fast and occurs in three distinct phases.     

Novel tetranuclear cubane-like Co(II) complexes involving chelate phosphoramide ligands

Interaction of cobalt(II) ions and sodium carbacylamidophosphates Na(L) (HL=PhC(O)NHP(O)(NR₂)₂; where NR₂ are morpholyl, HL¹; NMe₂, HL²; NEt₂, HL³) in methanol solution afforded polynuclear alkoxo complexes [Co₄{L¹}₃(OCH₃)₄(OH)(H₂O)₅·3H₂O] 1 and [Co₄{L}₄(OCH₃)₄(CH₃OH)₄] (L=L² 2, L³ 3). Data of spectral and TGA studies are presented. Coordination compounds 1 and 3 have been characterized by means of X-ray diffraction. Both the structures consist of tetranuclear cubane alkoxo clusters with methoxide ions bridging three metal centers (CoO 2.068(3)–2.093(4) Å) and phosphorylic ligands coordinated in a bidentatechelate fashion via the carbonyl oxygen atoms (CoO 1: 2.050(2); 3: 2.031(4) Å) and the phosphoryl groups (2.093(2) and 2.106(4) Å). Isolation of these cubane alkoxo complexes is an important proof for close resemblance in behavior of carbacylamidophosphate systems and β-diketonates towards transition metal ions.     

Crystal structure of a new supramolecular Ni(II) N 6-benzylaminopurine compound

A new mononuclear Ni(II) N ⁶-benzylaminopurine supramolecule [Ni(6-BA-H₂)₂(H₂O)₄]·(R)₂·4H₂O (1) (6-BA = N ⁶-benzylaminopurine (C₅H₂N₃NH)(NH)CH₂(C₆H₅), H₃R = 5-sulfosalicylic acid (C₆H₃)CO₂H· (OH)SO₃H) is firstly synthesized by the volatile method. Compound 1 possesses a 3D supramolecular structure built via H-bonds and π-π stacking interactions. In the structure, a mononuclear [Ni(6-BA-H₂)₂(H₂O)₄]⁶⁺ cation, in which the Ni(II) ion is 6-coordinated, bears six positive charges, and a fully deprotonated R^3? anion is located in the void surrounding the mononuclear cation to balance the charge.     

Substituted group-directed assembly of six coordination compounds based on pyrazole bifunctional ligands

Six new complexes [Mn₈(μ₄-O)₄(phpz)₈(MeOH)₄]·(MeOH)(H₂O) (1) [Co₂(HphpzH)(Hphpz)₂(phpz)₂]·4(MeOH) (2), Ni(Hphpz)₂ (3), [Ni(Hphpz)₂]·H₂O (4), [Zn₄(pzpy)₄Cl₄] (5) and [Cu₂(pzpy)₂(HCO₂)₂(H₂O)₂] (6) have been synthesized by hydrothermal reactions of MCl₂·4H₂O (M = Mn, Co, Ni, Zn or Cu) with 5-(2-hydroxyphenyl)-3-pyrazole (HphpzH) or 2-(1H-pyrazol-3-yl)pyridine (Hpzpy). The complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 is an octanuclear Mn(III) cluster, complexes 2 and 6 are binuclear Co(III) and Cu(II), respectively, complexes 3 and 4 are isomorphous mononuclear species, while complex 5 is a tetranuclear Zn(II) cluster. The magnetic behavior of complex 1 was investigated. Magnetic susceptibility measurements revealed antiferromagnetic exchange interactions between the metal centers in the clusters. The luminescence properties of the complexes were investigated at room temperature in the solid state.     

Butterfly and chair clusters using N,O-chelating ligands: A combined crystallographic and mass spectrometric study

The organic ligand (1-methyl-1H-benzo[d]imidazol-2-yl)methanol (HL¹) was used to react with Cu(ClO₄)₂·6H₂O and triethylamine at 80°C to afford the complex [Cu₄(L¹)₆]·(ClO₄)₂·CH₃CN ( 1 ). Every four-coordinated Cu(II) ion is surrounded with NO₃ coordinated environment, and every five-coordinated Cu(II) ion is surrounded with N₂O₃ coordinated environment. Changing the metal salt to Zn(NO₃)₂·6H₂O, and after adding CH₃COONa, afforded the complex [Zn₄(L¹)₄(NO₃)₂(CH₃COO)₂] ( 2 ), in which every five-coordinated Zn(II) ion is surrounded with NO₄ coordinated environment. High-resolution electrospray ionization mass spectrometry results revealed that complex 1 broke into the most stable fragment [Cu₂(L¹)₃]⁺, and it also can assemble high nuclear peaks in solution. For complex 2 , it was found that the complex exhibited different component distribution in solution. Not only were there substitutions between coordinated anions, but the high nuclear peaks could also be detected.