1-Ethylthio-2-[2-thienyltelluro]ethane (L) a new (Te, S) ligand: Synthesis and complexation with Ag(I), Cu(I), Pd(II) and Pt(II) – Single crystal structures of [PdCl2(L)] and bis(thienyl) tellurium(IV) chloride

Lithium 2-thienyltellurolate, generated from 2-thienyl lithium, reacts at −78 °C in THF with chloroethyl ethyl sulfide to give a (Te, S) ligand 1-ethylthio-2-[2-thienyltelluro]ethane (L) as a red oil. The complexes [PdCl₂(L)] (1), [PtCl₂(L)] (2), [Ag(L)₂][ClO₄] (3) and [CuBr(L)]₂ (4) were synthesized. The complex [HgCl₂(L)] on crystallization decomposed giving Th₂TeCl₂ (5) [where Th = 2-thienyl], which was characterized by X-ray diffraction on its single crystals. The ligand L and complexes 1–4 exhibit proton and carbon-13 NMR spectra, which are characteristic. The coordination through Te in 1–4 is indicated by downfield coordination shifts in the position of the TeCH₂ signal of L. Complex 1 was characterized by X-ray diffraction on its single crystals. The geometry around Pd is square planar. The Pd–Te, Pd–S and Pd–Cl bond lengths are 2.5040(4), 2.273(1) and 2.322(1)/2.380(1) Å, respectively. There are intermolecular interactions between Te (coordinated to Pd) and Cl, and sulfur and Cl. The Te–Cl and S–Cl distances, 3.401 and 3.488 Å, respectively, are shorter than the sum of the van der Waal’s radii (3.81 and 3.55 Å, respectively). The Pd–Pd distance between the two molecules is 3.4156(6) Å, greater than the sum of van der Waal’s radii (3.26 Å). The structure of 5 is typical of that of a tellurium(IV) compound (saw-horse type). The two Te–Cl bond lengths are identical, 2.480(1) Å. The geometry around Te in 5 can be best described as pseudo tetrahedral (trigonal bipyramidal with a lone pair on one corner of the triangle).     

2-(Phenyltelluromethyl)tetrahydrofuran (L) and 2-(2-{4-methoxyphenyl}telluroethyl)-1,3- dioxolane (L) and their palladium(II) and platinum(II) complexes

The nucleophile [ArTe⁻] generated in situ borohydride solution of Ar₂Te₂, reacts with 2-(chloromethyl) tetrahydrofuran and 2-(2-bromoethyl)-1,3-dioxolane resulting in L¹ and L², respectively. The complexes of palladium(II) and platinum(II) with L¹/L² having stoichiometries [MCl₂·L₂], [ML₂](ClO₄)₂, [(DPPE)ML₂](ClO)₄)₂, [(PPh₃)₂ML₂](ClO₄)₂ and [(phen)ML₂](ClO₄)₂ (where L = L¹/L² DPPE = Ph₂PC H₂CH₂PPh₂, PHEN = 1,10-phenanthroline and M = Pd/Pt) have been synthesized. IR, ¹H, ¹²⁵Te{¹H} and ³¹P{¹H} NMR and UV-vis spectral data of these species in conjunction with their molar conductance and molecular weight data have been used to authenticate the new species. In all complexes (1–20) the ligands L¹ and L² are coordinated through tellurium and in the complexes of formula [ML₂](ClO₄)₂ (M = Pd, Pt) the ligand is bidentate with the oxygen atom used in complexation. In solution, complexes PtCl₂L₂ exist as a mixture of cis and trans isomers whereas only the trans isomer was observed for the palladium analogues. The [(phen)PdL₂](ClO₄)₂(Q) quenches ¹O₂ readily. The plot of log [Q] vs time is linear. Mechanism compatible with the experimental observations is proposed.     

Preparation and X-ray characterization of two-coordinate Cu(I) complex of aliphatic thiolato ligand: Effect of steric bulk on coordination features

We have synthesized in a single-step procedure from available copper(I) precursor at RT two Cu(I) thiolato clusters of the formula [Cu₄(μ-SCH(CH₃)₂)₆]²⁻ and [Cu₅(μ-SC(CH₃)₃)₆]⁻ as revealed by X-ray crystallography, where increased steric bulk leads to a bigger cage with some two-coordinate metal centers. In addition, we identified a mononuclear two coordinate thiolato complex with the bulkier ligand, of the formula NEt₄[Cu(SC(CH₃)₃)₂]. This is only the second example of such a complex of an aliphatic ligand that is structurally characterized. The X-ray structure reveals an S–Cu–S angle of 176.7–179.5°, with Cu–S distances of 2.14 Å.     

Synthesis and magnetism of the first tetranuclear copper(II)–iron(III) complexes of macrocyclic oxamides

Four novel tetranuclear macrocyclic complexes of the formula [(CuLⁱ)₃Fe](ClO₄)₃·3H₂O (i=1–4, Lⁱ are the dianions of the [14]N₄ and [15]N₄ macrocyclic oxamides, namely 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene, 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene] have been prepared and characterized. These complexes are the first examples of oxamido-bridged Cu(II)–Fe(III) heterometallic species. Cryomagnetic studies on [(CuL¹)₃Fe](ClO₄)₃·3H₂O (1) and [(CuL³)₃Fe](ClO₄)₃·3H₂O (3) (77–300 K) revealed that the Cu(II) and Fe(III) ions interact antiferromagnetically through the oxamido bridge, with the exchange integral J=−30.8 cm⁻¹ for 1 and J=−28.7 cm⁻¹ for 3 based on . The interaction parameters have been compared with that of the related [Cu₃Mn] compound.     

Neutral pyridylmethylamide ligands and their mononuclear copper(II) complexes

Mononuclear copper(II) complexes of a family of pyridylmethylamide ligands HL, HL^Me, HL^Ph, HL^Me3 and HL^Ph3, [HL = N-(2-pyridylmethyl)acetamide; HL^Me = N-(2-pyridylmethyl)propionamide; HL^Ph = 2-phenyl-N-(2-pyridylmethyl)acetamide; HL^Me3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HL^Ph3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide], were synthesized and characterized. The reaction of copper(II) salts with the pyridylmethylamide ligands yields complexes [Cu(HL)₂(OTf)₂] (1), [Cu(HL^Me)₂](ClO₄)₂ (2), [Cu(HL)₂Cl]₂[CuCl₄] (3), [Cu(HL^Me3)₂(THF)](OTf)₂ (4), [Cu(HL^Me3)₂(H₂O)](ClO₄)₂ (5a and 5b), [Cu(HL^Ph3)₂(H₂O)](ClO₄)₂ (6), [Cu(HL)(2,2′-bipy)(H₂O)](ClO₄)₂ (7), and [Cu(HL^Ph)(2,2′-bipy)(H₂O)](ClO₄)₂ (8). All complexes were fully characterized, and the X-ray structures vary from four-coordinate square-planar, to five-coordinate square-pyramidal or trigonal-bipyramidal. The neutral ligands coordinate via the pyridyl N atom and carbonyl O atom in a bidentate fashion. The spectroscopic properties are typical of mononuclear copper(II) species with similar ligand sets, and are consistent their X-ray structures.     

Zn(II) complexes with pyridine derived N6 and N8 donor azamacrocyclic ligands

A novel N6 macrocyclic ligand, L¹ (2,8,14,20-tetramethyl-3,7,15,19,25,26-hexaaza-tricyclo[19.3.1.1^9,13]hexacosa-1(24),9,11,13(26),21(25),22-hexaene), was obtained by reduction of the 2 + 2 condensation product of 2,6-diacetylpyridine and propane-1,3-diamine. Zinc(II) complexes of L¹, of a related N8 macrocycle, L³ (3,6,9,17,20,23,29,30-octaaza-tricyclo[23.3.1.1[11,15]]triaconta-1(28),1,13,15(30),25(29),26-hexaene), similarly prepared by 2 + 2 condensation of 2,6-diformylpyridine and diethylenetriamine and of a tetra N-2-cyanoethyl derivative of a homologue of L¹ prepared from diformyl pyridine and ethane-1,2-diamine, L² (3-[6,14,17-tris-(2-cyano-ethyl)-3,6,14,17,23,24-hexaaza-tricyclo[17.3.1.1^8,12] tetracosa-1(23),8(24),9,11,19,21-hexaen-3-yl]-propionitrile), were prepared. Structures were determined for [ZnL¹](ClO₄)₂ · H₂O, [ZnL²](NO₃)₂ and [Zn₂L³(NO₃)₂](NO₃)₂ · H₂O. The [ZnL¹](ClO₄)₂ · H₂O and [ZnL²](NO₃)₂ complexes present a mononuclear endomacrocyclic structure with the metal in an octahedral distorted environment coordinated by the six donor nitrogen atoms from the macrocyclic backbone while the complex [Zn₂L³(NO₃)₂](NO₃)₂ · H₂O is dinuclear with both metal atoms into the macrocyclic cavity coordinated by four donor nitrogen atoms from the macrocyclic framework and one oxygen atom from one monodentate nitrate anion, in a distorted square pyramidal arrangement.     

Metal complexes of sterically hindered pyrzolylpyridines. The single crystal X-ray structure of [Cu(L)2]BF4 (L = 1-{pyrid-2-yl}-3-{2′,5′-dimethoxyphenyl}pyrazole)

Reaction of potassium 3{5}-(3′,4′-dimethoxyphenyl)pyrazolide with 2-bromopyridine in diglyme at 130°C for 3 days followed by an aqueous quench, affords 1-{pyrid-2-yl}-3-{3′,4′-dimethoxyphenyl}pyrazole (L²) in 69% yield after recrystallization from hot hexanes. Complexation of [Cu(NCMe)₄]BF₄ by 2 molar equivalents of 1-{pyrid-2-yl}-3-{2′,5′-dimethoxyphenyl}pyrazole (L¹) or L² in MeCN at room temperature, followed by concentration and crystallisation with Et₂O, gives [Cu(L)₂]BF₄ L = L¹, L²) in good yields. Treatment of AgBF₄ with L¹ or L² in MeNO₂ similarly gives [Ag(L)₂]BF₄ L = L¹, L²); reaction of AfBF₄ with L² in MeCN gives a product of stoichiometry [Ag(L²)(NCMe)]BF₄. The ¹H NMR spectra of the [M(L)₂]BF₄ complexes show peaks arising from a single coordinated environment. The single crystal X-ray structure of [Cu(L¹)₂]BF₄ shows a tetrahedral complex cation with Cu---N = 2.011(8), 2.036(8), 2.039(8), 2.110(8) Å. The Cu^I centre is close to tetrahedral, the dihedral angle between the least-squares planes formed by the Cu atom and the N donor atoms of the two ligands being 88.3(3)°. Complexation of hydrated Cu(BF₄)₂ by L² in MeCN at room temperature yields [Cu(L₂)₂](BF₄)₂. The cyclic voltammograms of the three Ag^I complexes in MeCN/0.1 M Bu₄ⁿ NPF₆ are suggestive of extensive ligand dissociation in this solvent.     

M(CO)4 (M = Mo or W) complexes of 2,6-bis(methylthiomethyl)pyridine (L) and 2,6-bis(p-tolylthiomethyl)pyridine (L): a dynamic NMR study

The hybrid S/N/S donor ligands 2,6-bis(methylthiomethyl)pyridine (L¹) and 2,6-bis(p-tolylthiomethyl)pyridine (L²) react with the [M(CO)₅(THF)] (M = Mo or W) compounds to form complexes of general formula [M(CO)₄L] (M = Mo, L = L²; M = W, L = L¹ or L²), where both L¹ and L² act in a S/N bidentate chelate fashion. In solution, these complexes undergo three fluxional processes, viz. inversion at the coordinated S atom, S¹–S² switching, and combined inversion and S¹–S² switching, leading to an interconversion of the four possible permutational isomers. Energy barriers for all three processes have been evaluated by standard one-dimensional band-shape analysis techniques. The mechanism of the S¹–S² switch is discussed.     

Electrospray ionization mass spectrometry of metal complexes. Gas phase formation of a binuclear copper(II)–5-Br-PADAP complex

The complexes formed from copper(II) and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP or HL) in aqueous methanol solution was studied by electrospray ionization mass spectrometry. The solution of a 1:1 complex of Cu(II) with 5-Br-PADAP showed five peaks assignable to a binuclear complex [Cu₂L₂(AcO)]⁺ and mononuclear complexes [CuL]⁺, [CuL(H₂O)]⁺, [CuL(AcOH)]⁺ and [CuL(HL)]⁺ (AcO=acetate). Collision activated dissociation revealed the relative order of bonding strengths; Cu–L>Cu–HL>CuL–AcOH>CuL–H₂O. The peak intensities of the binuclear complex showed second-order dependency on those of the mono complex. As for the solution of Ni(II)–5-Br-PADAP, no binuclear complex was observed in the mass spectra. Thus, it was suggested that [Cu₂L₂(AcO)]⁺ was formed by the fast gas phase reaction: 2[CuL]⁺+AcO⁻[Cu₂L₂(AcO)]⁺.     

Structural and spectral investigation on the Co complexes with 1,4-diazacycloheptane (DACH) functionalized by heterocyclic pendants

A series of penta-coordinated Co^II complexes of 1,4-diazacycloheptane (DACH) functionalized by additional imidazole or pyridine donor pendants, [CoL¹Cl](ClO₄)·H₂O (1), [CoL²Cl](ClO₄) (2) and [CoL³Cl](ClO₄)·CH₃OH (3), where L¹=1,4-bis(imidazole-4-ylmethyl)-DACH, L²=1,4-bis(N-1-methylimidazol-2-ylmethyl)-DACH and L³=1,4-bis(pyridyl-2-ylmethyl)-DACH have been synthesized and characterized by elemental analyses, IR and UV–Vis spectra. In all the mononuclear complexes, each Co^II center is penta-coordinated to four nitrogen donors of the ligand and one axial chloride anion. The crystal structure of complex 2 has been determined by X-ray diffraction analysis, which forms a one-dimensional linear structure through inter-molecular C–HCl and C–HO hydrogen-bonding.     

Syntheses, crystal structures and electronic properties of a series of copper(II) complexes with 3,5-halogen-substituted Schiff base ligands and their solutions

We have systematically investigated the structural features, electronic properties, thermally-induced structural phase transitions and absorption spectra depending on the solvent for ten Cu(II) complexes with 3,5-halogen-substituted Schiff base ligands. Structural characterization of two new complexes, bis(N-R-1-phenylethyl- and N-R,S-2-butyl-5-bromosalicydenaminato-κ²N,O)copper(II), reveals that they afford a compressed tetrahedral trans-[CuN₂O₂] coordination geometry with trans-N–Cu–N = 159.4(2)° and trans-O–Cu–O = 151.7(3)° for the 1-phenylethyl complex and trans-N–Cu–N = 157.9(3)° and trans-O–Cu–O = 151.0(3)° for the 2-butyl one. All the complexes exhibit a structural phase transition by heating in the solid state regardless of their structures at room temperature. The absorption spectra of a series of ten complexes exhibit a slight shift of the d–d band at 16 000–20 000 cm⁻¹ and remarkable shift of the π–π* band at 24 000–28 000 cm⁻¹, which suggests that the dipole moment of the solvents presumably affects the conformation of the π-conjugated moieties of the ligands rather than the coordination environment. We have also attempted ‘photochromic solute-induced solvatochromism’ by a system of bis(N-R-1-phenylethyl-3,5-dichlorosalicydenaminato-κ²N,O)copper(II) and photochromic 4-hydroxyazobenzene in chloroform solution. We successfully observed a change of the d–d and π–π* bands of the complex in the absorption spectra caused by cis–trans photoisomerization of 4-hydroxyazobenzene.     

Copper(I) and mercury(II) halide complexes of 1,2-bis(diphenylthioylphosphino)hydrazine

The reaction of 1,2-bis(diphenylthioylphosphino)hydrazine (L) with copper(I) and mercury(II) halides affords the complexes, [{CuLX}₂] (X = I, Br or Cl), [HgLX₂] (X = Cl or Br) and the tetrametallic complex, [{L(HgI₂)₂}₂]. Single crystal X-ray structures have been performed on the uncoordinated ligand, L, as well as the complexes [{CuLX}₂] (X = I, Br and Cl), [HgLBr₂] and [{L(HgI₂)₂}₂. The molecules of L exist as dimers as a result of pairs of N–HS hydrogen bonds. The copper(I) complexes are centrosymmetric dimetallic species, the two copper atoms being bridged by L and the X atoms. In all cases the coordination sphere around the Cu atoms is approximately trigonal pyramidal with an ‘S₂X₂’ donor set. The complex, [HgLBr₂], is a distorted tetrahedral monomer with an ‘S₂Br₂’ donor set and L acting as a bidentate thus forming a seven-membered chelate ring. The tetramercury iodo complex, [{L(HgI₂)₂}₂], contains two ‘L(HgI₂)₂’ units linked centrosymmetrically via an I atom from each moiety. The geometry around the Hg atoms is distorted tetrahedral. The influence of hydrogen bonding between the hydrazine backbone hydrogens of L and the coordinated halide ions in for the structures of the metal complexes is discussed.     

Synthesis, characterization and reactivity of palladium(II) compounds containing terdentate [Csp, N, S] or [Csp, N, S] ligands

The study of the reactivity of R---CH=N---(C₆H₄-2-SMe) with R=C₆H₅ or 2,4,6-Me₃-C₆H₂ with palladium(II) salts is reported. These studies have allowed us to prepare and characterize the coordination complexes: cis-[Pd{R---CH=N---(C₆H₄-2-SMe)}Cl₂] {R=C₆H₅ or 2,4,6-Me₃-C₆H₂} and the cyclopalladated compounds [Pd{C₆H₄---CH=N---(C₆H₄-2-SMe)}Cl] and [Pd{(2-CH₂-4,6-Me₂-C₆H₂)---CH=N---(C₆H₄-2-SMe)}Cl]. The X-ray crystal structures of the latter complexes reveal that the thioimines act as a [Csp², phenyl,N,S]⁻ and as a [Csp³, N,S]⁻ terdentate group, respectively. The study of the reactions of the cyclopalladated compounds with PPh₃ is also reported.     

N-Salicylideneaminoacidato copper(II) complexes as galactose oxidase model compounds

[CuL·B]^q model systems, where L²⁻ is the tridentate Schiff base ligand formed by the condensation of salicylaldehyde with alanine, B is imidazole, q=−1, 0 and +1, are optimized at B3LYP/6-31G* level of theory. Their electronic structure is described in terms of Mulliken population analysis and reactivity indices of Fukui. The total energy of [CuL·B]^q species increases with the electron removal. The reactivity indices suitable for the alcohol (sugar) adducts formation (CuO_sugar and O_phenoxylH_sugar interactions) are in the neutral molecule as well as in the singlet cation. Despite the similar trends in Cu–O_phenoxyl bonding and significant O_phenoxyl spin density in triplet cation, the catalytic mechanism of sugars oxidation proposed for the galactose oxidase cannot be used in our system because the [CuL·B]⁺ formation is energetically unfavorable. The imidazole nitrogen deprotonation is more probable than of the alanine ternary carbon atom.     

氮氧杂链型配体合成与Cu(Ⅱ)和Zn(Ⅱ)配位性质研究

合成了4种氮氧杂链型配体N,N'-二-(2-羟乙基)-乙二胺(L¹)、N-(2-羟基苄基)-丙醇胺(HL²)、N-(2-羟乙基)-N'-(2-羟基苄基)-乙二胺(HL³)和N-(2-羟乙基)-二乙三胺-(L⁴),通过元素分析、IR和¹H NMR等手段表征了其结构,用pH电位滴定法在25℃、I=0.10(KNO₃)条件下,测定了L¹和HL²与Cu(Ⅱ)离子以及HL³和L⁴与Zn(Ⅱ)离子配位平衡常数.结果表明:L¹和HL²与Cu(Ⅱ)离子配位时,均可生成四配位配合物,其中第三配位点醇羟基配位较强,其质子离解常数pK_a1分别为7.28和7.32;第四配位点是第2个醇羟基或1个水分子配位,其pK_a2分别为9.33和9.04;HL³和L⁴与Zn(Ⅱ)均可生成五配位配合物,第四配位点均为醇羟基,其离解常数pK_a1分别为7.76和7.96,第五配位点均为H₂O,其pK_a2分别为9.47和9.57.从上述热力学结果可见,配合物在中性pH值范围能生成亲核试剂Cu(Ⅱ)…^-OR或Zn(Ⅱ)…^-OR,而且均具备双重催化酯类底物水解的条件.     

“Wheel-and-axle” binuclear Cu(II) dioximates mediated by 1,2-bis(4-pyridyl)ethane: Synthesis, X-ray study and luminescent properties

The reaction of copper(II) acetate or fluoride with classic dioximes in the presence of 1,2-bis(4-pyridyl)ethane resulted in four novel compounds with the compositions [Cu₂(dmgH)₄bpe] (1), [Cu₂(NioxH)₄bpe] (2), [Cu₂(dpgH)₄bpe] (3), and [Cu₂(dpgH)₄bpe][Cu(dpgH)₂bpe]₂·2DMF (4) (where dmgH₂ = dimethylglyoxime, NioxH₂ = 1,2-cyclohexanedionedioxime, dpgH₂ = diphenylglyoxime, bpe = 1,2-bis(4-pyridyl)ethane, and DMF = N,N′-dimethylformamide), whose crystal structures were determined by single crystal X-ray diffraction. In the binuclear molecules 1-3, as well as in both binuclear and mononuclear molecules in 4 each Cu(II) atom has an identical N₅-environment formulated by four oximic nitrogen atoms of two monodeprotonated ligands in a slightly distorted square planar mode, and the nitrogen atom of the bpe molecule being in the apical position. The new compounds were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Luminescence investigations for 1, 2 and 4 were carried out to clarify whether the guest inclusion in the crystal lattice is accompanied by changes in the emission spectra.     

Experimental vapor pressures of 1,2-bis(dimethylamino)ethane, 1-methylmorpholine, 1,2-bis(2-aminoethoxy)ethane and N-benzylethanolamine between 273.18 and 364.97 K

In this work, the experimental vapor pressures of four amines 1,2-bis(dimethylamino)ethane, 1-methylmorpholine, 1,2-bis(2-aminoethoxy)ethane and N-benzylethanolamine using a static apparatus are reported. The temperature range is comprised between 273.18 and 364.97 K and the pressure range between 0.782 Pa and 333 kPa. The molar enthalpies of vaporization at 298.15 K were calculated from Clausius–Clapeyron equation fitted on the experimental results.     

2D Cu(I) and 3D mixed-valence Cu(I)/Cu(II) coordination polymers: Synthesis and structural characterization of [CuCl(pyz-H)2]·2H2O and [Cu2Cl2(pyz)(H2O)]·H2O (pyz-H = pyrazinic acid)

Two new coordination polymers of copper(I) chloride and pyrazinic acid (pyz-H), namely [CuCl(pyz-H)₂]·2H₂O (1) and [Cu₂Cl₂(pyz)(H₂O)]·H₂O (2) have been prepared and characterized by spectroscopic, magnetic and crystallographic methods. The overall physical measurements suggest that 1 is diamagnetic and contains monodentate N-pyrazinic acid, whereas 2 is paramagnetic and contains tridentate N,N′,O- chelating bridging pyrazinato anion. In the structure of 1 as elucidated by X-ray single crystal analysis, the asymmetric units [CuCl(pyz)₂] are linked together forming a zigzag chain with tetrahedral copper(I) environment. The two lattice water molecules form hydrogen bonds with the uncoordinated N atom and carboxylate group O atom of pyz-H molecules. The Cu–N bond lengths are 2.009(6) Å and Cu–Cl distances are 2.337(2) Å. Complex 2 has a three-dimensional structure with the chains [Cu(I)Cu(II)(C₅H₃N₂O₂)Cl₂(H₂O)] interconnected by [Cu(I)Cl₂N] tetrahedral unit and [Cu(II)NO₂Cl₂] polyhedra. The Cu(I)–Cl and Cu(I)–N distances are 2.327(2)–2.581(2) Å and 1.988(6) Å, respectively, whereas the Cu(II)–Cl and Cu(II)–N bond lengths are 2.258(2), 2.581(2) Å, and 2.017(6) Å, respectively. Hydrogen bonds of the type O–HO are formed between lattice and coordinated water, and carboxylate oxygens of pyrazinato ligand giving rise to a three-dimensional network. The Cl⁻ anions act as bridging ligands in both complexes. The magnetic data of complex 2 have been measured from 2 to 300 K and discussed.     

Cyano-bridged bimetallic complexes of copper(II) with tetracyanonickelate(II). Crystal structure of [Cu(dpt)Ni(CN)4]

Five new complexes of composition [Cu(dpt)Ni(CN)₄] (1) (dpt=dipropylenetriamine), [Cu(dien)Ni(CN)₄]·2H₂O (2) (dien=diethylenetriamine), [Cu(N,N′-dimeen)Ni(CN)₄]·H₂O (3) (N,N′-dimeen=N,N′-dimethylethylenediamine), [Cu(N,N-dimeen)Ni(CN)₄]·H₂O (4) (N,N-dimeen=N,N-dimethylethylenediamine) and [Cu(trimeen)Ni(CN)₄] (5) (trimeen=N,N,N′-trimethylethylenediamine) have been obtained by the reactions of the mixture of Cu(ClO₄)₂·6H₂O, appropriate amine and K₂[Ni(CN)₄] in water and have been characterized by IR and UV–Vis spectroscopies and magnetic measurements. The crystal structure of [Cu(dpt)Ni(CN)₄] (1) has been determined by single-crystal X-ray analysis. The structure of 1 consists of a one-dimensional polymeric chain ---Cu(dpt)---NC---Ni(CN)₂---CN---Cu(dpt)--- in which the Cu(II) and Ni(II) atoms are linked by CN groups. The nickel atom is four coordinate with four cyanide-carbon atoms (two cyano groups are terminal and two cyano groups (in cis fashion) are bridged) in a square-planar arrangement and the copper atom is five coordinate with two cyanide-nitrogen and three dpt-nitrogen atoms, in a distorted square-pyramidal arrangement. The temperature dependence of magnetic susceptibility (2–300 K) was measured for compound 1. The magnetic investigation showed the presence of a very weak antiferromagnetic interaction (J=−0.16 cm⁻¹) between the copper atoms within each chain through the diamagnetic Ni(CN)₄ ²⁻ ions.     

Supramolecular architecture of cadmium(II)–terephthalate complexes having a tridentate or tetradentate Schiff base as blocking coligand

Two new cadmium(II)–terephthalate complexes, _∞¹{[Cd₂(μ-terephthalate)₂(L¹)₂]·9H₂O} (1) and [{Cd(H₂O)(L²)}₂(μ-terephthalate)](terephthalate) · 10H₂O (2), where L¹ = (E)-N¹,N¹-diethyl-N²-(1-(pyridin-2-yl)ethylidene)ethane-1,2-diamine; L² = N,N′-bis-(1-pyridin-2-yl-ethylidene)-ethane-1,2-diamine; have been synthesized by a conventional solution method. Characterization by single crystal X-ray crystallography shows that compound 1 is composed of 1-D polymeric zig-zag chains with distorted pentagonal-bipyramidal cadmium centers. Compound 2 consists of centrosymmetric dinuclear complexes with a distorted pentagonal-bipyramidal cadmium center in which one terephthalate ligand bridges the metal centres and another terephthalate anion with water of crystallization forms a H-bonding network.