Synthesis,electrochemical and e.p.r. spectral studies of binuclear copper(II) complexes with new pentadentate L-proline-based binucleating ligands

The synthesis, reduction, optical and e.p.r. spectral properties of a series of new binuclear copper(II) complexes, containing bridging moieties (OH^–, MeCO₂ ^–, NO₂ ^–, and N₃ ^–), with new proline-based binuclear pentadentate Mannich base ligands is described. The ligands are: 2,6-bis[(prolin-1-yl)methyl]4-bromophenol [H₃L¹], 2,6-bis[(prolin-1-yl)methyl]4-t-butylphenol [H₃L²] and 2,6-bis[(prolin-1-yl)methyl]4-methoxyphenol [H₃L³]. The exogenous bridging complexes thus prepared were hydroxo: [Cu₂L¹(OH)(H₂O)₂] · H₂O (1a), [Cu₂L²(OH)(H₂O)₂] · H₂O (1b), [Cu₂L³(OH)(H₂O)₂] · H₂O (1c), acetato [Cu₂L¹(OAc)] · H₂O (2a), [Cu₂L²(OAc)] · H₂O (2b), [Cu₂L³(OAc)] · H₂O (2c), nitrito [Cu₂L¹(NO₂)(H₂O)₂] · H₂O (3a), [Cu₂L²(NO₂)(H₂O)₂] · H₂O (3b), [Cu₂L³(NO₂)(H₂O)₂] · H₂O (3c) and azido [Cu₂L¹(N₃)(H₂O)₂] · H₂O (4a), [Cu₂L²(N₃)(H₂O)₂] · H₂O (4b) and [Cu₂L³(N₃)(H₂O)₂] · H₂O (4c). The complexes were characterized by elemental analysis and by spectroscopy. They exhibit resolved copper hyperfine e.p.r. spectra at room temperature, indicating the presence of weak antiferromagnetic coupling between the copper atoms. The strength of the antiferromagnetic coupling lies in the order: NO₂ N₃ OH OAc. Cyclic voltammetry revealed the presence of two redox couples Cu^IICu^II Cu^IICu^I Cu^ICu^I. The conproportionality constant K _con for the mixed valent Cu^IICu^I species for all the complexes have been determined electrochemically.     

Synthesis and characterization of complexes of the first transition series cations with 2,2′-biimidazole and 2,2′-biimidazolate

Mononuclear [M(hfacac)₂(H₂biim)] complexes, where M = Mn^II, Fe^II, Co^II, Ni^II, Cu^II or Zn^II, hfacac = hexafluoroacetylacetonate, H₂biim = 2,2-biimidazole; dinuclear K₂[M₂(acac)₄(-biim)] (M = Cu^II or Zn^II) and tetranuclear K₂[M₄(acac)₈( ₄-biim)] (M = Co^II or Ni^II) complexes have been prepared and characterized by chemical analysis, conductance measurements, i.r., electronic and e.p.r. spectroscopies and by magnetic susceptibility measurements (in the 2–300 K range). Mn^II, Fe^II and Co^II are in a high spin state. The e.p.r. spectra of Cu^II and Mn^II compounds have been recorded.     

Synthesis,spectroscopy and thermal properties of the nickel(II), palladium(II) and copper(II) complexes of bis(aminoalkyl)-oxamides (=LH2) including the crystal structure of Cu2L(NO3)2

Summary The synthesis of the Ni^II, Pd^II and Cu^II complexes of N, N-bis(aminoalkyl)oxamides (LH₂) is described and structures are proposed on the basis of their physical and spectroscopic properties. With Ni^II and Pd^II only one complex is formed with general formula NiL or PdL, characterised by coordination through two deprotonated amide N-atoms and two terminal NH₂ groups. With Cu^II it proved possible to obtain three structurally different compounds, depending on the pH, with general formulae Cu(LH₂)X₂, Cu₂(L)X₂ and CuL in which X=Cl, Br or NO₃. The structure of [Cu₂(C₈O₂N₄H₁₆](NO₃)₂ was solved by means ofx-ray diffraction; Mr=451.33, monoclinic, space group P2₁/n, a=9.503(4), b=7.614(1), c=10.407(3) Å, =98.43(3)°, V=744.3(7)ų, Z=2, Dx=1.202 g cm^–3, =1.33 cm^–1, (MoK)=0.71073 Å, F(000)=520, room temperature, R=0.043, wR=0.047 for 1080 observed [I>-3(I)] not systematically absent reflections out of 1423 measurements and 137 variables. The compound has a conformational chair/boat disorder with 82% in the more stable chair form.     

N-Phthaloylglycinate ternary complexes with cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) metal ions and aromatic mono,bi and tridentate amines

Complexes of N-phthaloylglycinate (N-phthgly) and Co^II, Ni^II, Cu^II, Zn^II and Cd^II containing imidazole (imi), N-methylimidazole (mimi), 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen), and tridentate amines such as 2,2,2-terpyridine (terpy) and 2,4,6-(2-pyridyl)s-triazine (tptz), were prepared and characterized by conventional methods, i.r. spectra and by thermogravimetric analysis. For imi and mimi ternary complexes, the general formula [M(imi/mimi)₂(N-phthgly)₂]·nH₂O, where M = Co^II, Ni^II, Cu^II and Zn^II applies. For Cd^II ternary complexes with imi, [Cd(imi)₃(N-phthgly)₂]·2H₂O applies. For the bi and tridentate ligands, ternary complexes of the formula [M(L)(N-phthgly)₂]·nH₂O were obtained, where M = Co^II, Ni^II, Cu^II and Zn^II; L = bipy, phen, tptz and terpy. In all complexes, N-phthgly acts as a monodentate ligand, coordinating metal ions through the carboxylate oxygen, except for the ternary complexes of Co^II, Ni^II and Cu^II with mimi and Cu^II and Zn^II with imi, where the N-phthgly acts as a bidentate ligand, coordinating the metal ions through both carboxylate oxygen atoms.     

Redox, complexation, and substitution reactions in [Cu2B10H10]-2,2′-bipyridylamine-CH3CN system

Reaction of [Cu₂B₁₀H₁₀] with 2,2′-bipyridylamine (bpa) in acetonitrile was studied. A redox reaction was found to proceed in reaction solution at ambient temperature. Copper coordination compounds with the metal of different oxidation states—[Cu ₂ ^I (bpa)₂B₁₀H₁₀] · 2NCCH₃, [Cu ₄ ^II (bpa)₄(OH)₄][Cu ₂ ^I (B₁₀H₁₀)₃] · nNCCH₃, [Cu^II(bpa)₂(NCCH₃)₂](2-B₁₀H₉bpa)₂ · 2H₂O, [Cu ₂ ^II (bpa)₂(OH)₂B₁₀H₁₀], and [(Cu ₂ ^II (bpa)₂(CO₃)₂] · H₂O—were isolated under various reaction conditions. The compounds were characterized by IR spectroscopy, X-ray crystallography, and elemental analysis.     

Complexes of NS and NSO donor ligands. Nickel(II), copper(II) and cobalt(II) complexes of glyoxal bis(morpholineN-thiohydrazone) and diacetyl bis(morpholineN-thiohydrazone)

Summary Reactions of glyoxal bis(morpholineN-thiohydrazone), H₂gbmth, with NiCl₂·6H₂O, Ni(OAc)₂·4H₂O, Ni(acac)₂· H₂O, CuCl₂·2H₂O, Cu(OAc)₂·H₂O, Cu(acac)₂, CoCl₂· 6H₂O, Co(OAc)₂·4H₂O and Co(acac)₂·2H₂O yield complexes of the type [M(gbmth)], [M=Ni^II, Cu^II or Co^II]. Diacetyl reacts with morpholineN-thiohydrazide in the presence of nickel salts to yield [Ni^II(dbmth)], [Ni^II(dmth)(OAc)]H₂O and [Ni^II(Hdmth)(NH₃)Cl₂] involving N₂S₂ and NSO donor ligands. Copper and cobalt complexes of N₂S₂ and NSO donor ligands with compositions [Cu^II(dbmth)], [Co^II(dbmth)]·4H₂O and [Co^II(H₂dbmth)]Cl₂, have been isolated. The compounds have been characterised by elemental analyses, magnetic moments, molar conductance values and spectroscopic (electronic and infrared) data.     

Synthesis, characterisation and catalytic activities of manganese(III) complexes of pyridoxal-based ONNO donor tetradenatate ligands

Reaction of Mn^II(CH₃COO)₂ with dibasic tetradentate ligands, N,N′-ethylenebis(pyridoxylideneiminato) (H₂pydx-en, I), N,N′-propylenebis(pyridoxylideneiminato) (H₂pydx-1,3-pn, II) and 1-methyl-N,N′-ethylenebis(pyridoxylideneiminato) (H₂pydx-1,2-pn, III) followed by aerial oxidation in the presence of LiCl gives complexes [Mn^III(pydx-en)Cl(H₂O)] (1) [Mn^III(pydx-1,3-pn)Cl(CH₃OH)] (2) and [Mn^III(pydx-1,2-pn)Cl(H₂O)] (3), respectively. Crystal and molecular structures of [Mn(pydx-en)Cl(H₂O)] (1) and [Mn(pydx-1,3-pn)Cl(CH₃OH)] (2) confirm their octahedral geometry and the coordination of ligands through ONNO(2-) form. Reaction of manganese(II)-exchanged zeolite-Y with these ligands in refluxing methanol followed by aerial oxidation in the presence of NaCl leads to the formation of the corresponding zeolite-Y encapsulated complexes, abbreviated herein as [Mn^III(pydx-en)]-Y (4), [Mn^III(pydx-1,3-pn)]-Y (5) and [Mn^III(pydx-1,2-pn)]-Y (6). These encapsulated complexes are used as catalysts for the oxidation, by H₂O₂, of methyl phenyl sulfide, styrene and benzoin efficiently. Oxidation of methyl phenyl sulfide under the optimized reaction conditions gave ca. 86% conversion with two major products methyl phenyl sulfoxide and methyl phenyl sulfone in the ca. 70% and 30% selectivity, respectively. Oxidation of styrene catalyzed by these complexes gave at least five products namely styrene oxide, benzaldehyde, benzoic acid, 1-phenylethane-1,2-diol and phenylacetaldehyde with a maximum of 76.9% conversion of styrene by 4, 76.3% by 5 and 76.0% by 6 under optimized conditions. The selectivity of the obtained products followed the order: benzaldehyde > benzoic acid > styrene oxide > phenylacetaldehyde > 1-phenylethane-1,2-diol. Similarly, ca. 93% conversion of benzoin was obtained by these catalysts, where the selectivity of the products followed the order benzil > benzoic acid > benzaldehyde-dimethylacetal. Tests for the recyclability and heterogeneity of the reactions have also been carried. Neat complexes are equally active. However, the recycle ability of encapsulated complexes makes them better over neat ones.     

Novel mixed-ligand complexes of coumarilate/<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-diethylnicotinamide with some transition metals

Coordination complexes of transition metal cations (Co^II, Ni^II, Cu^II and Zn^II) containing coumarilate and N,N′-diethylnicotinamide were synthesized. The structural characterization and thermal behaviour analysis of novel samples synthesized were conducted through elemental analysis, magnetic susceptibility, solid-state UV–Vis, direct and injection probe mass spectra, FTIR spectra, thermoanalytic TG-DTG/DTA and single crystal X-ray diffraction methods. The structural details of single crystals of [Co(dena)₂(H₂O)₄](coum)₂ (I) and [Cu(coum)₂(dena)₂(H₂O)₂] (III) complexes were resolved completely. Moreover, the results of analysis obtained for [Ni(coum)₂(dena)₂(H₂O)₂] (II) and [Zn(dena)₂(H₂O)₄](coum)₂ (IV) complexes were interpreted considering the samples with crystal structures defined and made assumptions about the structural details. It was determined that the complex of Co^II metal cation has salt-type structure and the coordination number of metal is accomplished to six as the sum of 4 mol of water and also 2 mol of N,N′-diethylnicotinamide ligands in trans position located within the coordination sphere. It was observed that 2 mol of coumarilate anions are located outside the coordination sphere and have stabilized to the charge (2+) of metal. The Cu^II complex has totally molecular structure, and the coordination sphere of metal cation was 6 as the sum of 2 mol of water, 2 mol of N,N′-diethylnicotinamide and 2 mol of monoanionic monodentate coumarilate ligands. All ligands have been located in –trans position. The geometry of both complex structures is distorted octahedral. It is assumed that the Ni^II complex structure is isostructural with Cu^II complex structure and also does Zn^II complex with Co^II structure. It was determined that the decomposition products obtained from thermal analysis are the oxides of related metal cations.     

Oligonuclear 3d–4f Complexes as Tectons in Designing Supramolecular Solid‐State Architectures: Impact of the Nature of Linkers on the Structural Diversity

Heteronuclear cationic complexes, [LCuLn]³⁺ and [(LCu)₂Ln]³⁺, were employed as nodes in designing high‐nuclearity complexes and coordination polymers with a rich variety of network topologies (L is the dianion of the Schiff base resulting from the 2:1 condensation of 3‐methoxysalycilaldehyde with 1,3‐propanediamine). Two families of linkers have been chosen: the first consists of exo‐dentate ligands bearing nitrogen‐donor atoms (bipyridine (bipy), dicyanamido (dca)), whereas the second consists of exo‐dentate ligands with oxygen‐donor atoms (anions derived from the acetylenedicarboxylic (H₂acdca), fumaric (H₂fum), trimesic (H₃trim), and oxalic (H₂ox) acids). The ligands belonging to the first family prefer copper(II ) ions, whereas the ligands from the second family interact preferentially with oxophilic rare‐earth cations. The following complexes have been obtained and crystallographically characterized: [LCu^II(OH₂)Gd^III(NO₃)₃] ( 1 ), [{LCu^IIGd^III(NO₃)₃}₂(μ‐4,4′‐bipy)] ( 2 ), [LCu^IIGd^III(acdca)_1.5(H₂O)₂] ? 13 H₂O ( 3 ), [LCu^IIGd^III(fum)_1.5(H₂O)₂] ? 4 H₂O ? C₂H₅OH ( 4 ), [LCu^IISm^III(H₂O)(Hfum)(fum)] ( 5 ), [LCu^IIEr^III(H₂O)₂(fum)]NO₃ ? 3 H₂O ( 6 ), [LCu^IISm^III(fum)_1.5(H₂O)₂] ? 4 H₂O ? C₂H₅OH ( 7 ), [{(LCu^II)₂Sm^III}₂fum₂](OH)₂ ( 8 ), [LCu^IIGd^III(trim)(H₂O)₂] ? H₂O ( 9 ), [{(LCu^II)₂Pr^III}(C₂O₄)_0.5(dca)]dca ? 2 H₂O ( 10 ), [LCu^IIGd^III(ox)(H₂O)₃][Cr^III(2,2′‐bipy)(ox)₂] ? 9 H₂O ( 11 ), and [LCuGd(H₂O)₄{Cr(CN)₆}] ? 3 H₂O ( 12 ). Compound 1 is representative of the whole family of binuclear Cu^II–Ln^III complexes which have been used as precursors in constructing heteropolymetallic complexes. The rich variety of the resulting structures is due to several factors: 1) the nature of the donor atoms of the linkers, 2) the preference of the copper(II ) ion for nitrogen atoms, 3) the oxophilicity of the lanthanides, 4) the degree of deprotonation of the polycarboxylic acids, 5) the various connectivity modes exhibited by the carboxylato groups, and 6) the stoichiometry of the final products, that is, the Cu^II/Ln^III/linker molar ratio. A unique cluster formed by 24 water molecules was found in crystal 11 . In compounds 2 , 3 , 4 , 9 , and 11 the Cu^II–Gd^III exchange interaction was found to be ferromagnetic, with J values in the range of 3.53–8.96 cm^?1. Compound 12 represents a new example of a polynuclear complex containing three different paramagnetic ions. The intranode Cu^II–Gd^III ferromagnetic interaction is overwhelmed by the antiferromagnetic interactions occurring between the cyanobridged Gd^III and Cr^III ions.     

N-Ferrocenylcarbonyl-N′-benzoylhydrazine and its transition metal(II) complexes

Summary A new ferrocene derivative, N-ferrocenylcarbonyl-N-benzoylhydrazine (H₂FB) and its transition metal complexes, [M(FB)]₂·H₂O (M = Mn^II, Co^II, Cu^II, Zn^II, Cd^II or Hg^II) and M(HFB)₂·nH₂O (M = Mn^II or Cd^II) were prepared by reacting H₂FB with the metal(II) acetates and characterized by elemental analyses, i.r. and u.v. spectroscopy and t.g.a. H₂FB appears to act as a tetradentate ligand, coordinating to the metal through the nitrogen enolic oxygen atoms.     

Hydrolysis of [Pt(dien)H2O]2+ and [Pd(dien)H2O]2+ complexes in water

The hydrolysis of the [Pt(dien)H₂O]²⁺ and [Pd(dien)H₂O]²⁺ complexes has been investigated by potentiometry at 298 K, in 0.1 mol dm^–3 aqueous NaClO₄. Least-squares treatment of the data obtained indicates the formation of mononuclear and -hydroxo-bridged dinuclear complexes with stability constants: log ₁₁ = –6.94 for [Pt(dien)OH]⁺, log ₁₁ = –7.16 for [Pd(dien)OH]⁺, and also log ₂₂ = –9.37 for [Pt₂(dien)₂(OH)₂]²⁺ and log ₂₂ = –10.56 for [Pd₂(dien)₂(OH)₂]²⁺. At pH values > 5.5, formation of the dimer becomes significant for the Pt^II complex, and at pH > 6.5 for the Pd^II complex. These results have been analyzed in relation to the antitumor activity of Pt^II complexes.     

Paramagnetic and diamagnetic binuclear copper(II) complexes with different bidentate exogenous bridges: synthesis, spectroscopy and magnetic properties

Summary Four binuclear Cu^II complexes, [Cu₂(L)(-X)], have been prepared and characterized, where H₃L is a 2:1 Schiff base derived from 2-hydroxy-1-naphthaldehyde and 1,3-diamino-2-propanol and X = 1,3-N₃ (1), C₃H₃N₂ (pyrazolate) (2), AcO (3) and PhCO₂ (4). The Cu^IIions are bridged by endogenous alkoxide and bidentate exogenous bridges. The variable-temperature magnetic analyses show that complexes (2)–(4) exhibit antiferro-magnetic coupling with the exchange integrals, 2J, from- 188 to -158 cm^-1. The -1,3-azide-bridged binuclear Cu^II complex (1) shows the essential features of diamagnetism through measurements of its variable-temperature susceptibility and e.p.r. spectra. The results suggest that (1) can act as a diamagnetic model for metazidohemocyanin.     

Synthesis,crystal structures,and properties of copper(II) dicarboxylate complexes with [bis(2-pyridylcarbonyl)amido]

Four new complexes, [Cu₂(Bpca)₂(L¹)(H₂O)₂] · 3H₂O (I), [Cu₂(Bpca)₂(L²)(H₂O)₂] (II), [Cu₂(Bpca)₂(L³)] · 2H₂O (III), [Cu₂(Bpca)₂(L¹)(H₂O)] · 2H₂O (IV) (Bpca = bis(2-pyridylcarbonyl)amido, H₂L¹ = glutaric acid, H₂L² = adipic acid, H₂L³ = suberic acid, H₂L⁴ = azelaic acid) have been synthesized and characterized by single-crystal X-ray diffraction methods (CIF files CCDC nos. 1432836 (I), 1432835 (II), 817411 (III), and 817412 (IV)), elemental analyses, IR spectra. Structural analyses reveal that compounds I, II, and IV have similar structures [Cu(Bpca)]⁺ units bridged by dicarboxylate forming dinuclear units, whereas the dinuclear of compound III are edge-shared through two carboxylate oxygen atoms of different suberate anions. Hydrogen bonds are response for the supramolecular assembly of compounds I to IV. The temperature-dependent magnetic property of III was also investigated in the temperature range of 2 to 300 K, and the magnetic behaviour suggests weak antiferromagnetic coupling exchange.     

Complexes of tris(o-phenanthroline)nickel(II) and copper(II) bromide with dithiocarbamates derived from α-amino acids

Complexes of 1,10-o-phenanthroline (o-phen)-Ni^II and Cu^II with dithiocarbamates derived from -amino acids (glycine, phenylalanine, alanine, methionine and tryptophan) were synthesized and characterized by chemical analysis, spectral and thermal studies and by biological screening; the complexes are non-electrolytes. The empirical formula are [Ni(o-phen)₂(aadtc)] and [Cu₂(o-phen)₂(phaladtc)(H₂O)₂Br₂] where, aadtc = glycinyl-, phenylalaninyl-, alaninyl-, methioninyl- and tryptophanyldithiocarbamate and phaladtc = phenylalaninyldithiocarbamate. The structure of these complexes is probably octahedral. Molecular association through hydrogen bonding between the —NH and the carboxylate groups is proposed for the Ni^II complexes. The Cu^II complex is dimeric with the phenylalaninyldithiocarbamate acting as a bridge.     

Mixed metal complexes in solution. Thermodynamic and spectrophotometric study of copper(II)-citrate heterobinuclear complexes with nickel(II), zinc(II) or cadmium(II) in aqueous solution

Summary A thermodynamic study of Cu^II–M^II-citrate (M^II=Ni^II, Zn^II or Cd^II) ternary systems has been performed by means of potentiometric measurements of hydrogen ion concentration at different temperatures (10, 25, 35 and 45°C) and at I=0.1 mol dm^–3 (KNO₃).The different binary and ternary systems involved have been further characterized by visible spectra and by calculating the spectra ( versus ) of all the Cu^II complexes.The thermodynamic data suggest strong entropic stabilization for the species under discussion. As regards the visible spectral characteristics of Cu^II(d-d transitions), the substitution of one Cu^II ion in the dimer [Cu₂(cit)₂H_–2]^4– by Ni^II or Zn^II to form heterobinuclear [CuM(cit)₂H_–2]^4– complexes, gives rise to a change in the visible spectrum.     

Synthesis and magnetic properties of copper(II) bis(phenylsulphinyl)ethane complexes

Summary Two Cu^II complexes, [Cu₂(-L)Cl₄·H₂O (1) and Cu₂(-L)Cl₄ (2) [-L and -L = meso- and rac-PhS(O)(CH₂)₂S(O)Ph, respectively], were synthesized and characterized by elemental analysis, i.r. spectra and molar conductances. In each case, the Cu^II ion bonds to the 557-01 moiety through oxygen, and may be bridged by the ligand (-L or -L). From magnetic moment measurements at room temperature and variable temperature magnetic susceptibilities, we suggest that complexes (1) and (2) exhibit weak ferromagnetic behaviour.     

The dangers of using KBr,KI and CaI2 as mulling agents during the preparation of infrared discs of complexes

Tribochemical reactions of KBr, KI and CaI₂ with [Cu(L)Cl₂(EtOH)_3/2(H₂O)]1/2H₂O (L = formylhydrazine) give novel Cu^I and Cu^II complexes, which have been characterized by elemental analyses, spectral (i.r., u.v.–vis., ¹H-n.m.r.) and magnetic measurements. The i.r. spectra indicate that (L) behaves in a monodentate manner, coordinating via the azomethine nitrogen (C-N) group in the Cu^II complexes, but behaving as a bidentate ligand, via the carbonyl oxygen and NH₂ groups in the Cu^I complexes. KI and CaI₂ react with [Cu(L)Cl₂(EtOH)_3/2(H₂O)]-1/2H₂O in the solid state, accompanied by a colour change, substitution of the chloride by iodide ions, and reduction of Cu^II to Cu^I to give complexes with formulae [Cu(L)I(EtOH)_1/2] and [Cu_1.7(L)I_1.7(EtOH)_1/2]. On the other hand, the tribochemical reaction of KBr with [Cu(L)Cl₂(EtOH)_3/2(H₂O)]1/2H₂O is accompanied by a colour change; substitution of the chloride by bromide ions, but without reduction of Cu^II and yields a complex of formula [Cu(L)₂Br₂(EtOH)(H₂O)]1/2EtOH. The spectral and magnetic results suggest a distorted octahedral geometry for the Cu^II complexes while a tetrahedral geometry around the Cu^I ion. The non-stoichiometric structure of [Cu_1.7(L)I_1.7(EtOH)_1/2] is discussed.     

Copper(II) and nickel(II) complexes of N,N′-bis(2-cyanoethyl)-5, 7-dioxo-1,4,8,11-tetra-azacyclotetradecane

Summary Reaction of 5,7-dioxo-1,4,8,11-tetra-azacyclotetradecane with acrylonitrile gives the dicyanoethylated ligand (L). The Cu^II complex [CuLH_-2]·2H₂O has been isolated from basic solution where the macrocycle is deprotonated and acts as a dinegative quadridentate ligand. The ligand L is protonated in acidic solution and the ionisation equilibria can be summarised as LH _inf2 ^sup2+ LH⁺ +H⁺; K₁ LH⁺ L + H⁺; K₂ where pK₁ = 3.05 and pK₂ = 5.94 at 25 °C and I = 0.1 mol dm^-3 (NaNO₃). Complexation with Cu^II can be represented by the equilibria at 25 °C. Cu²⁺ + L [CuLH_-1]⁺ + H⁺; log_{11 – 1} = -3.43 Cu²⁺ + L [CuLH_-2] + 2H²⁺; log_{11 – 2} = -9.18 For Ni^II only the single equilibrium is of importance. Ni²⁺ + L [NiLH_-2] + 2H²⁺; log_{11 – 2} = -14.45     

Cyanido-bridged one-dimensional systems assembled from [ReIVCl4(CN)2]2? and [MII(cyclam)]2+ (M = Ni, Cu) precursors

Three new cyanido-bridged heterometallic Re^IVNi^II and Re^IVCu^II one-dimensional systems were synthesized and extensively characterized both structurally and magnetically. Single-crystal X-ray diffraction analysis revealed that these compounds display a common topology, with chains composed of alternating [Re^IVCl₄(CN)₂]^2? and [M^II(cyclam)]²⁺ (M = Ni in 1, Cu in 2) or [Cu^II(N,N??-dimethylcyclam)]²⁺ (in 3) building units. Two different chain orientations with a tilt angle of ca. 51° to 55° are present in the crystal packing of these compounds. The magnetic susceptibility measurements suggest the presence of intrachain ferromagnetic interactions between the S = 3/2 Re^IV centers and the 3d metal ions: S = 1 Ni^II or S = 1/2 Cu^II. At low temperature, a three-dimensional ordered magnetic phase induced by interchain antiferromagnetic interactions (antiferromagnetic for 1 and 2; canted antiferromagnetic for 3) is detected for the three compounds.     

Copper(II) oxalate and oxamate complexes

Reaction of Cu^II salts with phenanthroline and oxalate (ox) or oxamate (oxm) gives [Cu(phen)(ox)(H₂O)] · H₂O or [Cu(phen)(oxm)(H₂O)] · H₂O complexes while direct treatment of Cu^II salts with oxalate or oxamate gives [NH₄]₂[Cu(ox)₂] and [Cu(oxm)₂(H₂O)₂] respectively. The X-ray structures of one example of each system, aquo-oxamato-phenanthroline-copper(II)-dihydrate and the polymeric ammonium-bis(aquo)-tetraoxalato-dicopper(II)-dihydrate, are reported.