Synthesis,Structure, and Magnetic Characterization of a Series of Iron(II) Coordination Frameworks with 2, 6‐Bis(1, 2,4‐triazole‐4‐yl)pyridine

Based on the bis‐triazole ligand 2, 6‐bis(1, 2,4‐triazole‐4‐yl)pyridine (L), the triazole‐iron(II) complexes [Fe(L)₂(dca)₂(H₂O)₂] · 2H₂O ( 1 ) (Nadca = sodium dicyanamide), {[Fe(μ₂‐L)₂(H₂O)₂]Cl₂}_n ( 2 ), and {[Fe(μ₂‐L)₂(H₂O)₂](ClO₄)₂ · L · H₂O}_n ( 3 ) were isolated by solvent diffusion methods. When iron(II) salts and Nadca were used, compound 1 was isolated, which contains mononuclear Fe(L)₂(dca)₂(H₂O)₂ units. When FeCl₂ or FeClO₄ were used, one‐dimensional (1D) cation iron(II) chains ( 2 ) and two‐dimensional (2D) cation iron(II) networks ( 3 ) were isolated indicating anion directing structural diversity. Moreover, variable‐temperature magnetic susceptibility data of 1 – 3 were recorded in the temperature range 2–300 K. The magnetic curve of complex 2 was fitted by using the classical spin Heisenberg chain model indicating anti‐ferromagnetic interactions (J = –5.31 cm^–1). Obviously complexes 1 – 3 show no detectable thermal spin crossover behaviors, the lack of spin‐crossover behavior may be correlated with FeN₄O₂ coordination spheres in 1 – 3 .     

I-substituted imidazolemanganese(II) complexes

Summary A series of manganese(II) spin-free complexes of the type: MnL_n Cl₂ [L =N-Methylimidazole (MeIm), n = 1,2,3,6; L =_N-ethylimidazole (EtIm), n = 4], MnL_nBr₂ (L = MeIm, n = 2, 4, 6; L = EtIm, n = 4, 6), MnL_nI₂ (L = MeIm, n = 4, 6; L = EtIm, n = 6), MnL_n(NCS)₂ (L = MeIm, n = 3, 4; L = EtIm, n = 4), MnL₆X₂ (L = MeIm, EtIm; X = NO₃, ClO₄, BF₄); (Me₄N)(MnLCl₃)(L = MeIm, EtIm); (Et₄N)[Mn(MeIm)Br₃] and Mn(MeIm)₂(N₃)₂ · 5 H₂O were prepared and characterized. The complexes have either octahedral, distorted octahedral, polymeric octahedral or tetrahedral structures.     

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and its Complexes with Copper(II) Chloride and Copper(II) Perchlorate

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole (hnt), prepared by alkylation of 3‐nitro‐1, 2, 4‐triazole with 2‐chloroethanol, was found to react with copper(II) chloride and copper(II) perchlorate in acetonitrile/ethanol solutions giving complexes [Cu₂(hnt)₂Cl₄(H₂O)₂] and[Cu(hnt)₂(H₂O)₃](ClO₄)₂, respectively. They are the first examples of coordination compounds with a neutral N‐substituted 3‐nitro‐1, 2, 4‐triazole ligand. 1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and the obtained complexes were characterized by NMR and IR spectroscopy, X‐ray, and thermal analyses. [Cu₂(hnt)₂Cl₄(H₂O)₂] presents a dinuclear chlorido‐bridged complex in which hnt acts as a chelating bidentate ligand, coordinated to the metal by a nitrogen atom of the triazole ring and an oxygen atom of the nitro group, and the copper atoms are inconsiderably distorted octahedral coordination. [Cu(hnt)₂(H₂O)₃](ClO₄)₂comprises a mononuclear complex cation, in which two nitrogen atoms of two hnt ligands in trans configuration and three water oxygen atoms form a square pyramidal environment around the copper atom, which is completed to an distorted octahedron with a bifurcated vertex due to two additional elongated Cu–O bonds with two nitro groups. In both complexes, Cu–O bonds with the nitro groups may be considered as semi‐coordinated.     

Metallkomplexe mit N2O2S2‐Koordinationssphäre. Synthese und Charakterisierung der Cobalt(II)‐, Nickel(II)‐ und Kupfer(II)‐Komplexe eines 15‐ und eines 16‐gliedrigen N,N′‐bis(2‐hydroxyethyl)‐funktionalisierten makrocyclischen Liganden

Metal Complexes with N₂O₂S₂ Donor Set. Synthesis and Characterization of the Cobalt(II), Nickel(II), and Copper(II) Complexes of a 15‐ and a 16‐Membered Bis(2‐hydroxyethyl) Pendant Macrocyclic Ligand The macrocyclic ligands 6, 10‐bis(2‐hydroxyethyl)‐7, 8, 9, 11, 17, 18‐hexahydro‐dibenzo‐[e, n][1, 4, 8, 12]‐dithiadiaza‐cyclopentadecine ( 1 ) (L¹) and 5, 13‐bis(2‐hydroxyethyl)‐7, 8, 9, 10, 16, 17, 18, 19, 20‐nonahydro‐dibenzo‐[g, o][1, 9, 5, 13]‐dithiadiaza‐cyclohexadecine (L⁴) have been prepared. They form the stable complexes [CoL¹(‐H)CoL¹](ClO₄)₃ ( 2 ), [NiL¹](ClO₄)₂·MeOH ( 3 ), Λ‐[CuL¹](ClO₄)₂·MeOH ( 4a ) and rac‐[CuL¹](ClO₄)₂·MeOH ( 4b ), [NiL⁴](ClO₄)₂ ( 5 ), and [CuL⁴](ClO₄)₂ ( 6 ). The compounds 1 to 6 have been characterized by standard methods and single‐crystal X‐ray diffraction. In the complexes 2 to 6 the metal atoms are octahedrally coordinated by the N₂O₂S₂ donor set of the ligands. L¹ and L⁴ are folded herein along the N···M···S‐ and the N···M···N′‐axes, respectively. This results at the metal atom in a all‐cis‐configuration for the complexes of L¹ and a trans‐N₂‐cis‐O₂‐cis‐S₂‐configuration for the complexes of L⁴. The cobalt(II) complex 2 is a dimer, bridged by a rather short hydrogen bridge of 2.402(12)Å length. The copper(II) complexes of L¹ and L⁴ differ with respect to the Jahn‐Teller‐distortion.     

A novel series of M(II) complexes of 6‐methylpyridine‐2‐carboxylic acid with 4(5)methylimidazole: Synthesis,crystal structures, α‐glucosidase activity,density functional theory calculations and molecular docking

Novel complexes of 6‐methylpyridine‐2‐carboxylic acid and 4(5)methylimidazole, namely [Mn(6‐mpa)₂(4(5)MeI)₂] ( 1 ), [Zn(6‐mpa)₂(4(5)MeI)₂] ( 2 ), [Cd(6‐mpa)₂(4(5)MeI)₂] ( 3 ), [Co(6‐mpa)₂(4(5)MeI)₂] ( 4 ), [Ni(6‐mpa)₂(4(5)MeI)(OAc)] ( 5 ) and [Cu(6‐mpa)₂(4(5)MeI)] ( 6 ), were synthesized for the first time. The structures of complexes 1 – 4 and complexes 5 and 6 were determined using X‐ray diffraction and mass spectrometric techniques, respectively. The experimental spectral analyses for these complexes were performed using Fourier transform infrared and UV–visible techniques. The α‐glucosidase inhibition activity values (IC₅₀) of complexes 1 – 6 were identified in view of genistein reference compound. Moreover, the DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level was used to obtain optimal molecular geometry and vibrational wavenumbers for complexes 1 – 6 . Electronic spectral behaviours and major contributions to the electronic transitions were investigated using TD‐DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level with conductor‐like polarizable continuum model and SWizard program. Finally, in order to investigate interactions between the synthesized complexes ( 1 – 6 ) and target protein (template structure S. cerevisiae isomaltase), a molecular docking study was carried out.     

Desulfuration and Cyclization of (Z)‐2‐[Amino(pyridine‐2‐yl)methylene]‐ hydrazonecarbothioamide in the Presence of Manganese(II)

The reaction of (Z)‐2‐[amino(pyridine‐2‐yl)methylene]hydrazonecarbothioamide (HAm4DH) with Mn(ClO₄)₂·6H₂O afforded different mononuclear or polynuclear manganese(II) complexes, the nature of which apparently depended on the solvent used. For example, in ethanol a compound of formula [Mn(HAm4DH)₂](ClO₄)₂ ( 1 ) was obtained, where HAm4DH coordinates as a common tridentate NNS donor, but the [Mn(bpy)₂(NCS)₂] complex ( 2 ) (bpy = 2,2'‐bipyridine) has also been obtained – probably due to C–N bond cleavage of the thiosemicarbazone. Nevertheless, in a basic aqueous medium [Mn(bpy)₃](ClO₄)₂·0.5bpy ( 3 ) is formed and there is structural evidence for chemical transformations of the thiosemicarbazone promoted by Mn^II. Thus, the sulfate in {[Mn(py)₄Mn(py)₂(H₂O)₂(μ‐SO₄)₂]·4H₂O}_n ( 4 ) or sulfate and cyclooctasulfur in [Mn(pta)₂(pdo)]₄(SO₄)₂·4H₂O·S₈] ( 5 ), where pta is 3‐(pyridin‐2‐yl)‐1,2,4‐triazol‐5‐amine and pdo is (2R,4R/2S,4S)‐pentane‐2,4‐diolato, arise from the desulfuration and oxidation of the thiosemicarbazone ligand. The structures of complexes 2 to 5 were established by single‐crystal X‐ray diffraction. The formation of pta is the result of the oxidative cyclization of HAm4DH. In the polynuclear complex 4 , the sulfate acts as an (O,O') bridge between alternating Mn(py)₂(H₂O)₂ and Mn(py)₄ centers. In the tetranuclear complex 5 , pta acts as a bischelating ligand through the N‐pyridine and N‐triazole, and pdo act as a bridge between two manganese atoms. It is also noteworthy that in complexes 4 and 5 hydrogen bonds give rise to different self‐assembly behaviour that leads to complicated supramolecular structures.     

Synthesis,Crystal Structures and Properties of Tetrametallic Complexes: [M2(phen)4(FCA)2](ClO4)2·(H2O)2 (M=Zn or Co,phen=1,10‐phenanthroline,FCA=anion of 3‐ferrocenyl‐2‐crotonic acid)

Two new complexes [Zn₂(phen)₄(FCA)₂](ClO₄)₂·(H₂O)₂ ( 1 ) and [Co₂(phen)₄ (FCA)₂](ClO₄)₂·(H₂O)₂ (2) (FCA=anion of 3‐ferrocenyl‐2‐crotonic acid, phen=1,10‐phenanthroline) have been synthesized, and characterized by elemental analysis, IR, UV‐Vis spectra, thermal analyses, and single‐crystal X‐ray diffraction. Two M(II) (M=Zn or Co) ions are bridged by two FCA anions with syn‐anti bridging ligands, leading to dimeric cores, [M₂(phen)₄(FCA)₂]²⁺, and each M(II) ion is six‐coordinated in a distorted octahedral geometry by two chelate phen ligands and two μ₂‐carboxylate oxygen atoms from two FCA groups. The M(II)…M(II) intradimer distances are 0.4391 and 0.4462 nm in 1 and 2 , respectively. Electrochemical properties of the complexes have been discussed.     

Synthesis and Characterization of Tetrahedral Zinc(II) Complexes with 3, 6,7‐Triamino‐7H‐[1, 2,4]triazolo[4, 3‐b][1, 2,4]triazole as Nitrogen‐Rich Ligand

Triaminotriazolotriazole (TATOT) was used as a nitrogen‐rich ligand for the formation of the energetic Zn^II complexes [ZnCl₂(TATOT)₂] · H₂O ( 2 ), [Zn(H₂O)(TATOT)₃](NO₃)₂ · 2H₂O ( 3 ), and [Zn(TATOT)₄](ClO₄)₂ · 2H₂O ( 4 ). The zinc species were prepared in a straightforward and inexpensive synthesis. The complexes 2 – 4 were structurally characterized using X‐ray diffraction. Additionally, the compounds were characterized using elemental analysis and infrared (IR) spectroscopy. Finally, the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA) and BAM (Bundesanstalt für Materialforschung und ‐prüfung) methods.     

Synthesis,Crystal Structure and Photoluminescence Property of Zinc(II), Cadmium(II), and Lead(II) Complexes with Bidentate Ligand: 1‐(1‐Imidazolyl)‐4‐(imidazol‐1‐ylmethyl)benzene (IIMB)

Assembly of bidentate ligand 1‐(1‐imidazolyl)‐4‐(imidazol‐1‐ylmethyl)benzene (IIMB) with varied metal salts of Zn^II, Cd^II and Pb^II provide three new complexes, [Zn(IIMB)₂](ClO₄)₂·2H₂O ( 1 ), [Cd(IIMB)₂(SCN)₂] ( 2 ) and [Pb(IIMB)₂(SCN)](SCN) ( 3 ). Single crystal X‐ray diffraction studies revealed that complexes 1 and 2 display a similar one‐dimensional double stranded chain structure, while complex 3 is a slight distorted rhombohedral grid network with (4,4) topology. The results indicate that the coordination geometry of the metal ion and the counter anion have great impact on the structure of the complexes. In addition, the photoluminescence properties of ligand IIMB and complexes 1 – 3 were studied in the solid state at room temperature.     

Synthesis and Crystal Structures of Bis(1‐{(E)‐2‐pyridinylmethylidene}‐semicarbazone)iron(II) and ‐copper(II) Diperchlorate Monohydrates

The pyridine‐2‐carbaldehyde semicarbazone ligand (HL) reacts with iron(II) and copper(II) perchlorates in boiling ethanol to yield red‐violet [Fe^II(HL)₂](ClO₄)₂·H₂O ( 1 ) and light‐green crystals [Cu^II(HL)₂](ClO₄)₂·H₂O ( 2 ). The crystals are triclinic with the metal ions in an octahedral environment, coordinated to two nitrogen and one oxygen‐donor atom from HL. Electronic, magnetic and electrochemical properties are presented as well.     

(4,4′‐Bipyridine)mercury(II) Coordination Polymers,Syntheses, and Structures

Mercury(II) complexes with 4,4′‐bipyridine (4,4′‐bipy) ligand were synthesized and characterized by elemental analysis, and IR, ¹H‐ and ¹³C‐NMR spectroscopy. The structures of the complexes [Hg₃(4,4′‐bipy)₂(CH₃COO)₂(SCN)₄]_n ( 1 ), [Hg₅(4,4′‐bipy)₅(SCN)₁₀]_n ( 2 ), [Hg₂(4,4′‐bipy)₂(CH₃COO)₂]_n(ClO₄)_2n ( 3 ), and [Hg(4,4′‐bipy)I₂]_n ( 4 ) were determined by X‐ray crystallography. The single‐crystal X‐ray data show that 2 and 4 are one‐dimensional zigzag polymers with four‐coordinate Hg‐atoms, whereas 1 is a one‐dimensional helical chain with two four‐coordinate and one six‐coordinate Hg‐atom. Complex 3 is a two‐dimensional polymer with a five‐coordinate Hg‐atom. These results show the capacity of the Hg‐ion to act as a soft acid that is capable to form compounds with coordination numbers four, five, and six and consequently to produce different forms of coordination polymers, containing one‐ and two‐dimensional networks.     

Syntheses,Crystal Structures,and Properties of Three Copper(II) Complexes Constructed by 4‐(4,6‐Bis(1H‐pyrazol‐1‐yl)‐1,3,5‐triazin‐2‐yl)morpholine

Three copper(II) complexes of the polydentate N‐donor ligand [4‐(4,6‐bis(1H‐pyrazol‐1‐yl)‐1,3,5‐triazin‐2‐yl)morpholine] (L) with chlorides, nitrates, and perchlorates as anions, namely, [CuCl₂(L)] · 0.5(MeCN) ( 1 ), [Cu(NO₃)₂(H₂O)(L)] · (MeCN) ( 2 ), and [Cu(L)₂](ClO₄)₂ · (MeCN) ( 3 ) were synthesized and structurally characterized by IR, elemental analysis and X‐ray crystallographic analysis. In these complexes, the L ligand binds the copper(II) cation in the tridentate N₃ form. The coordination arrangement around the central copper(II) atom is distorted square‐pyramidal in 1 but it is distorted octahedral in 2 and 3 . The interesting noncovalent interactions such as hydrogen bonds, π–π stacking, and anion–π interactions present in the solid‐state structures are discussed. The crystal results reveal that the counteranions play important roles in determining the diverse structures of these complexes. Moreover, the PXRD, TG, DRS, and fluorescence properties of compounds 1 – 3 were investigated.     

Zweikernige Palladium(II)‐, Platin(II)‐ und Iridium(III)‐Komplexe von Bis[imidazol‐4‐yl]alkanen

Dinuclear Palladium(II), Platinum(II), and Iridium(III) Complexes of Bis[imidazol‐4‐yl]alkanes The reaction of bis(1,1′‐triphenylmethyl‐imidazol‐4‐yl) alkanes ((CH₂)_n bridged imidazoles L(CH₂)_nL, n = 3–6) with chloro bridged complexes [R₃P(Cl)M(μ‐Cl)M(Cl)PR₃] (M = Pd, Pt; R = Et, Pr, Bu) affords the dinuclear compounds [Cl₂(R₃P)M–L(CH₂)_nL–M(PR₃)Cl₂] 1 – 17 . The structures of [Cl₂(Et₃P)Pd–L(CH₂)₃L–Pd(PEt₃)Cl₂] ( 1 ), [Cl₂(Bu₃P)Pd–L(CH₂)₄L–Pd(PBu₃)Cl₂] ( 10 ), [Cl₂(Et₃P)Pd–L(CH₂)₅L–Pd(PEt₃)Cl₂] ( 3 ), [Cl₂(Et₃P)Pt–L(CH₂)₃L–Pt(PEt₃)Cl₂] ( 13 ) with trans Cl–M–Cl groups were determined by X‐ray diffraction. Similarly the complexes [Cl₂(Cp*)Ir–L(CH₂)_nL–Ir(Cp*)Cl₂] (n = 4–6) are obtained from [Cp*(Cl)Ir(μ‐Cl)₂Ir(Cl)Cp*] and the methylene bridged bis(imidazoles).     

Novel Platinum(II) Complexes with Dipyridyl Containing Chelating Ligands and their Products with the Model Nucleobases 1‐Methylthymine and 1‐Methyluracil

The reactions of [Pt(dpma)(H₂O)₂]²⁺ (dpma = 2,2′‐dipyridylmethylamine) and [Pt(dpk)(H₂O)₂]²⁺ (dpk = 2,2′‐dipyridylketone) with the model nucleobases 1‐methylthymine (1‐MeT) and 1‐methyluracil (1‐MeU) were studied. Reaction products were characterized by ¹⁹⁵Pt NMR spectroscopy and by X‐ray structure analysis. The symmetric dpma and dpk diaqua complexes form dinuclear complexes with 1‐methylthymine, acting as secondary bridging ligand via its N3 and O4 donor atoms. [Pt₂(dpma)₂(1‐MeT)₂](ClO₄)₂ · H₂O ( 5 ) and [Pt₂(dpk)(dpk · H₂O)(1‐MeT)₂](PF₆)₂ · 4 H₂O ( 6 ) both show a head‐to‐head arrangement. Biological tests show a significant in vitro antitumor activity of [Pt(dpk)Cl₂] against the human glioma cell line U 87.     

Synthesis,Spectroscopy, and Structures of Mono‐ and Dinuclear Copper(I) Halide Complexes with 1,3‐Imidazolidine‐2‐thiones

Copper(I) halides with triphenyl phosphine and imidaozlidine‐2‐thiones (L ‐NMe, L ‐NEt, and L ‐NPh) in acetonitrile/methanol (or dichloromethane) yielded copper(I) mixed‐ligand complexes: mononuclear, namely, [CuCl(κ¹‐S‐L ‐NMe)(PPh₃)₂] ( 1 ), [CuBr(κ¹‐S‐L ‐NMe)(PPh₃)₂] ( 2 ), [CuBr(κ¹‐S‐L ‐NEt)(PPh₃)₂] ( 5 ), [CuI(κ¹‐S‐L ‐NEt)(PPh₃)₂] ( 6 ), [CuCl(κ¹‐S‐L ‐NPh)(PPh₃)₂] ( 7 ), and [CuBr(κ¹‐S‐L ‐NPh)(PPh₃)₂] ( 8 ), and dinuclear, [Cu₂(κ¹‐I)₂(μ‐S‐L ‐NMe)₂(PPh₃)₂] ( 3 ) and [Cu₂(μ‐Cl)₂(κ¹‐S‐L ‐NEt)₂(PPh₃)₂] ( 4 ). All complexes were characterized with analytical data, IR and NMR spectroscopy, and X‐ray crystallography. Complexes 2 – 4 , 7 , and 8 each formed crystals in the triclinic system with P$\bar{1}$ space group, whereas complexes 1 , 5 , and 6 crystallized in the monoclinic crystal system with space groups P2₁/c, C2/c, and P2₁/n, respectively. Complex 2 has shown two independent molecules, [(CuBr(κ¹‐S‐L ‐NMe)(PPh₃)₂] and [CuBr(PPh₃)₂] in the unit cell. For X = Cl, the thio‐ligand bonded to metal as terminal in complex 4 , whereas for X = I it is sulfur‐bridged in complex 3 .     

Heterodinuclear Ruthenium(II) Complexes of the Bridging Ligand 1,6,7,12‐Tetraazaperylene with Iron(II), Cobalt(II), Nickel(II), as well as Palladium(II) and Platinum(II)

The first heterodinuclear ruthenium(II) complexes of the 1,6,7,12‐tetraazaperylene (tape) bridging ligand with iron(II), cobalt(II), and nickel(II) were synthesized and characterized. The metal coordination sphere in this complexes is filled by the tetradentate N,N′‐dimethyl‐2,11‐diaza[3.3](2,6)‐pyridinophane (L‐N₄Me₂) ligand, yielding complexes of the general formula [(L‐N₄Me₂)Ru(µ‐tape)M(L‐N₄Me₂)](ClO₄)₂(PF₆)₂ with M = Fe {[ 2 ](ClO₄)₂(PF₆)₂}, Co {[ 3 ](ClO₄)₂(PF₆)₂}, and Ni {[ 4 ](ClO₄)₂(PF₆)₂}. Furthermore, the heterodinuclear tape ruthenium(II) complexes with palladium(II)‐ and platinum(II)‐dichloride [(bpy)₂Ru(μ‐tape)PdCl₂](PF₆)₂ {[ 5 ](PF₆)₂} and [(dmbpy)₂Ru(μ‐tape)PtCl₂](PF₆)₂ {[ 6 ](PF₆)₂}, respectively were also prepared. The molecular structures of the complex cations [ 2 ]⁴⁺ and [ 4 ]⁴⁺ were discussed on the basis of the X‐ray structures of [ 2 ](ClO₄)₄ · MeCN and [ 4 ](ClO₄)₄ · MeCN. The electrochemical behavior and the UV/Vis absorption spectra of the heterodinuclear tape ruthenium(II) complexes were explored and compared with the data of the analogous mono‐ and homodinuclear ruthenium(II) complexes of the tape bridging ligand.     

Cyano‐Bridged ‘Oximato’ Complexes: Synthesis,Structure, and Catalase‐Like Activities

The reaction of the ‘oximato’‐ligand precursor A (Fig. 1) and metal salts with KCN gave two mononuclear complexes [ML(CN)(H₂O)_n](ClO₄) ( 1 and 2 ; L={N‐(hydroxy‐κO)‐α‐oxo‐N′‐[(pyridin‐2‐yl‐κN)methyl[1,1′‐biphenyl]‐4‐ethanimidamidato‐κN′}; M=Co^II ( 1 ), Cu^II ( 2 ); n=2 for Co^II, n=0 for Cu^II; Figs. 2 and 3). The new cyano‐bridged pentanuclear ‘oximato’ complexes [{ML(H₂O)_n(NC)}₄M¹(H₂O)_x](ClO₄)₂ ( 3 – 6 ) and trinuclear complexes [{ML(H₂O)_n(NC)}₂M¹L](ClO₄) ( 7 – 10 ) ([M¹=Mn^II, Cu^II; x=2 for Mn^II, x=0 for Cu^II] were synthesized from mononuclear complexes and characterized by elemental analyses, magnetic susceptibility, molar conductance, and IR and thermal analysis. The four [ML(CN)(H₂O)_n]⁺ moieties are connected by a metal(II) ion in the pentanuclear complexe 3 – 6 , each one involving four cyano bridging ligands (Fig. 4). The central metal ion displays a square‐planar or octahedral geometry, with the cyano bridging ligands forming the equatorial plane. The axial positions are occupied by two aqua ligands in the case of the central Mn‐atom. The two [ML(CN)(H₂O)_n]⁺ moieties and an ‘oximato’ ligand are connected by a metal(II) ion in the trinuclear complexes 7 – 10 , each one involving two cyano bridging ligands (Fig. 5). The central metal ions display a distorted square‐pyramidal geometry, with two cyano bridging ligands and the donor atoms of the tridentate ‘oximato’ ligand. Moreover catalytic activities of the complexes for the disproportionation of hydrogen peroxide (H₂O₂) were also investigated in the presence of 1H‐imidazole. The synthesized homopolynuclear Cu^II complexes 6 and 10 displayed eficiency in disproportion reactions of H₂O₂ producing H₂O and dioxygen thus showing catalase‐like activity.     

A copper(II)–pyrazole complex cation with imposed symmetry

The reaction of Cu(ClO₄)₂·6H₂O, NaAsF₆ and excess pyrazole yields hexakis­(pyrazole‐κN²)copper(II) bis­(hexa­fluoroarsenate), [Cu(C₃H₄N₂)₆](AsF₆)₂ or [Cu(pzH)₆](AsF₆)₂ (pzH is pyrazole), (I). The analogous hexakis­(pyrazole‐κN²)copper(II) hexafluorophosphate perchlorate complex, [Cu(C₃H₄N₂)₆](PF₆)_1.29(ClO₄)_0.71 or [Cu(pzH)₆](PF₆)_1.29(ClO₄)_0.71, (II), is obtained in a similar fashion, using KPF₆ in place of NaAsF₆. Both compounds contain the hitherto unknown [Cu(pzH)₆]²⁺ complex cation, in which the copper(II) ion lies at the center of a regular octahedron of coordinated N atoms. The cation has crystallographically imposed symmetry. The X‐ray data indicate that the lack of the expected distortion can be accounted for by the presence of either static Jahn–Teller disorder or dynamic Jahn–Teller distortion.     

Two 2,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazo­le–metal complexes (M = Cu and Ni)

The reaction of the diazine ligand 3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazole (pod, C₁₂H₈N₄O), with Cu(CF₃SO₃)₂ or Ni(ClO₄)₂ afforded the title complexes di­aqua­bis­[3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazole‐N²,N³]copper(II) bis­(tri­fluoro­methane­sul­fon­ate), [Cu(pod)₂(H₂O)₂](CF₃SO₃)₂, and di­aqua­bis­[3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazo­le‐N²,N³]­nickel(II) diperchlorate, [Ni(pod)₂(H₂O)₂](ClO₄)₂. Both complexes present a crystallographically centrosymmetric mononuclear cation structure which consists of a six‐coordinated Cu^II or Ni^II ion with two pod mol­ecules acting as bidentate ligands and two axially coordinated water mol­ecules.     

The development of phosphinoamine–Pd(II)–imidazole complexes: implications in room‐temperature Suzuki–Miyaura cross‐coupling reaction

The reaction of N‐methylimidazole (N‐MeIm) and N‐butylimidazole (N‐BuIm) with the complexes [PdCl₂(PPh₂py–P,N)] and [PdCl₂(PPh₂Etpy–P,N)] in the presence of NH₄PF₆ under N₂ at room temperature afforded four new cationic Pd(II) complexes [PdCl(PPh₂py–P,N)(N‐MeIm)](PF₆) ( 1 ), [PdCl(PPh₂py–P,N)(N‐BuIm)](PF₆) ( 2 ), [PdCl(PPh₂Etpy–P,N)(N‐MeIm)](PF₆) ( 4 ) and [PdCl(PPh₂Etpy‐P,N)(N‐BuIm)](PF₆) ( 5 ) in good yields, where PPh₂py is 2‐(diphenylphosphino)pyridine and PPh₂Etpy is 2‐{2‐(diphenylphosphino)ethyl}pyridine). The complexes were fully characterized. The catalytic activities of these complexes were investigated for Suzuki–Miyaura cross‐coupling reactions at room temperature. Complex 2 exhibited excellent activity compared to other analogs. Copyright © 2013 John Wiley & Sons, Ltd.