Tansition metal complexes with 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL): Synthesis and crystal structure of [Co(L)2(H2O)4] · 6H2O and [Cu(L)2(H2O)2] · 4H2O

Transition metal complexes of 2-(1-(carboxymethyl)-2-methyl-1H-benzimidazol-3-ium-3-yl)acetate (HL), namely [Co(L)₂(H₂O)₄] · 6H₂O (I) and [Cu(L)₂(H₂O)₂] · 4H₂O (II), have been synthesized by a hydrothermal procedure and characterized by X-ray crystallography, CIF files CCDC nos. 1007524 (I), 1007525 (II). Both I and II are mononuclear molecules. In I, the Co²⁺ ion is in octahedral coordiantion environment and surrounded by four O atoms from water molecules and two carboxylate O atoms of two deprotonated ligand (L^?) occupied six culmination. While in II, the Cu²⁺ ion is located in a square-planar geometry, bounded to two aqua O atoms and two carboxylate O atoms from L^?.     

Facile strategies for the synthesis and crystallization of linear trinuclear nickel(II)-Schiff base complexes with carboxylate bridges: Tuning of coordination geometry and magnetic properties

Three new linear trinuclear nickel(II) complexes, [Ni₃(salpen)₂(OAc)₂(H₂O)₂]·4H₂O (1) (OAc = acetate, CH₃COO⁻), [Ni₃(salpen)₂(OBz)₂] (2) (OBz = benzoate, PhCOO⁻) and [Ni₃(salpen)₂(OCn)₂(CH₃CN)₂] (4) (OCn = cinnamate, PhCHCHCOO⁻), H₂salpen = tetradentate ligand, N,N′-bis(salicylidene)-1,3-pentanediamine have been synthesized and characterized structurally and magnetically. The choice of solvent for growing single crystal was made by inspecting the morphology of the initially obtained solids with the help of SEM study. The magnetic properties of a closely related complex, [Ni₃(salpen)₂(OPh)₂(EtOH)] (3) (OPh = phenyl acetate, PhCH₂COO⁻) whose structure and solution properties have been reported recently, has also been studied here. The structural analyses reveal that both phenoxo and carboxylate bridging are present in all the complexes and the three Ni(II) atoms remain in linear disposition. Although the Schiff base ligand and the syn–syn bridging bidentate mode of the carboxylate group remain the same in complexes 1–4, the change of alkyl/aryl group of the carboxylates brings about systematic variations between six- and five-coordination in the geometry of the terminal Ni(II) centres of the trinuclear units. The steric demand as well as hydrophobic nature of the alkyl/aryl group of the carboxylate is found to play a crucial role in the tuning of the geometry. Variable-temperature (2–300 K) magnetic susceptibility measurements show that complexes 1–4 are antiferromagnetically coupled (J = −3.2(1), −4.6(1), −3.2(1) and −2.8(1) cm⁻¹ in 1–4, respectively). Calculations of the zero-field splitting parameter indicate that the values of D for complexes 1–4 are in the high range (D = +9.1(2), +14.2(2), +9.8(2) and +8.6(1) cm⁻¹ for 1–4, respectively). The highest D value of +14.2(2) and +9.8(2) cm⁻¹ for complexes 2 and 3, respectively, are consistent with the pentacoordinated geometry of the two terminal nickel(II) ions in 2 and one terminal nickel(II) ion in 3.     

Crystal structure and magnetic properties of dicarboxylate-bridged linear chain Mn(II) complexes

Two manganese(II) complexes, [Mn(mtm)(CH₃OH)₂(H₂O)]_n (1) and [Mn₂(mtm)₂(2,2′-bipy)₂]_n (2) (bipy=bipyridine, mtm=[bis(methylthio)methylene]malonate) were synthesized and characterized by X-ray crystallography. Structure of 1 consists of octahedral manganese(II) species which are extended by carboxylate bridges in syn–anti fashion along the c-axis. Chains of 1 are associated by hydrogen bonding among coordinating water and methanol molecules and carboxylate oxygen atoms, forming two-dimensional structures. The crystallographic asymmetric unit of 2 comprises two [Mn(2,2′-bipy)(mtm)] units in which Mn(II) atoms are bridged by μ₂-oxygens from carboxylate to form Mn₂O₂ rhombus. The dimeric units are linked doubly by second carboxylates in syn–anti fashion, resulting in a chain structure. The antiferromagnetic coupling of Mn(II) ions in 1 (−0.2 cm⁻¹) and 2 (−1.57 cm⁻¹) was determined from variable-temperature magnetic susceptibility data in the temperature range of 2–300 K.     

MCl4n− (AuCl4−, PtCl42−, or PdCl42−) anion extraction from NanMCl4 in water using a tetraimidazolium macrocyclic receptor

Highly effective exaction (up to 97%) of noble metal Au, Pt, or Pd as MCl₄^n? form (i.e., AuCl₄^?, PtCl₄^2?, or PdCl₄^2?) from Na_nMCl₄ aqueous solution have been achieved on the basis of the interactions between MCl₄^n? and cyclo[2](2,6-di(1H-imidazol-1-yl)pyridine)[2](2,6-bisbromomethyl)pyridine (1⁴⁺).     

Synthesis, crystal structure, hydrogen bonding and spectroscopy of transition-metal complexes with the ligand (N,N′-bis(2-pyridylmethyl)-1,3-propanediamine)

Six mononuclear complexes are reported with the tetradentate ligand N,N′-bis(2-pyridylmethyl)-1,3-propanediamine, (abbreviated as pypn) i.e. [Cu(pypn)(ClO₄)₂](H₂O)_1/2 (1), [Fe(pypn)Cl₂](NO₃) (2), [Zn(pypn)Cl](ClO₄) (3), [Co(pypn)(NCS)₂](ClO₄) (4), [Co(pypn)(N₃)₂](ClO₄) (5), [Zn(pypn)(NCS)₂] (6). The synthesis and X-ray crystal structures of all six compounds and their spectroscopic properties are presented.The geometry of the Cu²⁺, Co³⁺, Zn²⁺, Fe³⁺ ions is essentially octahedrally based, with the mm conformation (for Cu) and m_sf conformations for the other 3 metal ions; in compound 3 the geometry around the Zn²⁺ is distorted trigonal bipyramidal. The stabilisation of the crystal lattices is maintained by interesting, relative strong hydrogen bonds.     

Crystal and molecular structures of mixed-valence octanuclear cobalt(ii,iii) propionate and butyrate with an etagere-like core

The new mixed-valence octanuclear cobalt carboxylate complexes [Co^II ₄Co^III ₄(μ₄-O)₄-(μ₃-OMe)₄(μ-O₂CR)₆(O₂CR)₂(H₂O)₆]·4H₂O, where R = Et (3) or n-Pr (4), were investigated by X-ray diffraction analysis. Complexes 3 and 4 have a molecular octanuclear structure, and they are valence trapped, and contain four cobalt atoms Co³⁺ in the central cubane fragment with four cobalt atoms Co²⁺ at the periphery of the molecules. The molecules of the complexes are stabilized by four intramolecular hydrogen bonds and are linked, together with water solvent molecules, by intermolecular hydrogen bonds to form a three-dimensional supramolecular system.     

The Indigo Isomer Epindolidione as a Redox-Active Bridging Ligand for Diruthenium Complexes

Epindolidione (H₂L), a heteroatom-modified analogue of tetracene and a structural isomer of indigo, forms dinuclear complexes with [RuX₂]²⁺, X=bpy (2,2′-bipyridine, [ 1 ]²⁺) or pap (2-phenylazopyridine, [ 2 ]²⁺), in its doubly deprotonated bridging form μ-L²⁻. The dications in compounds meso-[ 1 ](ClO₄)₂ and meso-[ 2 ](ClO₄)₂, [X₂Ru(μ-L)RuX₂](ClO₄)₂, contain five-membered chelate rings N-C−C-O-Ru^II with π bridged metals at an intramolecular distance of 7.19 Å. Stepwise reversible oxidation and reduction is mainly ligand centered (oxidation: L²⁻; reduction: X), as deduced from EPR of one-electron oxidized and reduced intermediates and from UV/Vis/NIR spectroelectrochemistry, supported by TD-DFT calculation results. The results for [ 1 ](ClO₄)₂ and [ 2 ](ClO₄)₂ are qualitatively similar to the ones observed with the deprotonated indigo-bridged isomers with their six-membered chelate ring structures, confirming the suitability of both π systems for molecular electronics applications, low-energy absorptions, and multiple electron transfers.     

Synthesis, characterization and DNA-binding characteristics of Ru(II) molecular light switch complexes

A series of four polypyridyl Ru(II) complexes such as [Ru(L)₄(PIP)]²⁺ and [Ru(L)₄PPIP]²⁺ where L is 4-amino pyridine and Pyridine (PIP?=?2-phenylimidazo[4,5-f] [1, 10] phenanthroline), (PPIP?=?2-(4??-phenoxy-phenyl) imidazo[4,5-][1, 10]phenanthroline) have been synthesized and characterized by elemental analysis, physicochemical methods such as UV?Cvis, IR and NMR spectroscopic techniques. The DNA-binding behavior of these complexes was investigated by electronic absorption titrations, fluorescence spectroscopy, viscosity measurements and salt-dependent studies. The experimental results indicate that all these complexes can bind to DNA through an intercalation mode, the DNA-binding affinities of these complexes follow the order [Ru(4-APy)₄(PPIP)]²⁺(1)?>?[Ru(Py)₄PPIP]²⁺(2)?>?[Ru(4-APy)₄(PIP)]²⁺(3)?>?[Ru(Py)₄PIP]²⁺(4). Noticeably, these complexes have been found to be efficient photosensitisers for strand scissions in plasmid DNA. Further, all four complexes screened for their antimicrobial activity indicate that the complexes show appreciable activity against Escherichia coli and Neurospora Crassa. In addition, in the presence of Co²⁺, the emission of DNA-[Ru(L₄)PPIP/PIP]²⁺ can be quenched and recovered by the addition of EDTA, which exhibited the DNA ??light switch?? properties.     

A convenient MnIII starting material for the synthesis of homo- and heterometallic manganese carboxylate clusters: Mn9 and Mn10−xFex complexes

The use of a convenient source of Mn^III ions, namely the [Mn(OR)(O₂CR′)₂]_n (R = H, Me, and R′ = Me, Bu^t) family of 1-D coordination polymers, afforded two new enneanuclear and decanuclear molecular clusters, homometallic [Mn₉O₇(O₂CBu^t)₁₃(MeCN)₂] (3) and heterometallic [Mn_10?xFe_x(OMe)₂₀(O₂CMe)₁₀] (x < 10) (4), respectively. Compound 3 was synthesized by a solvent-induced structural transformation, whereas complex 4 resulted from the reaction of [Mn(OH)(O₂CMe)₂]_n with an Fe^III source. The core of 3 comprises two [Mn₄O₂]⁸⁺ butterfly units and a [Mn₃O]⁷⁺ triangular unit fused together by sharing one Mn atom. Magnetic susceptibility measurements of 3 revealed dominant antiferromagnetic interactions within the molecule, and a ground state of S = 1 with many low-lying excited states. Complex 4 is a mixed Fe^III/Mn^III single-strand molecular wheel, which forms 3D nanotubular stacks arranged in a zig–zag fashion. The described work suggests that the [Mn(OR)(O₂CR′)₂]_n compounds represent excellent starting materials for Mn^III carboxylate cluster chemistry.     

Structurally rigid bis(pyrazolyl)pyridine Zn(II) and Cu(II) complexes: Structures and kinetic studies in ring‐opening polymerization of ε‐caprolactone

Four bis(pyrazolyl)pyridine Zn(II) and Cu(II) carboxylate complexes have been structurally elucidated and used as initiators in the ring‐opening polymerization (ROP) of ε‐carprolactone (ε‐CL). Reactions of bis(3,5‐dimethyl‐pyrazol‐1‐yl)pyridine ( L1 ) with the appropriate Zn(II) and Cu(II) carboxylates afforded the corresponding complexes; [Zn(L1)(C₆H₅COO)₂] ( 1 ), [Zn(L1)(2‐Cl‐C₆H₄COO)₂] ( 2 ), [Zn(L1)(OAc)₂] ( 3 ) and [Cu(L1)(OAc)₂] ( 4 ) in moderate to good yields. Molecular structures of compounds 1 , 2 , 3 confirmed the presence of one tridentate bound ligand L1 in the metal coordination sphere and two carboxylate anions to give five coordination number around Zn(II) and Cu(II) atoms. Complexes 1 , 2 , 3 , 4 initiated the ROP of ε‐CL at 110 °C to give polymers of moderate molecular weights. Kinetic analyses of the ROP reactions indicate pseudo ‐first‐order dependency on ε‐CL monomer and initiator. ¹H NMR and mass spectral data established a coordination insertion mechanistic pathway and behaviour of 1 , 2 , 3 , 4 as initiators in the ROP of ε‐CL. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and structural properties of thiapyridinophane and its complex with Ni(II) and Ag(I)

The 2,11-dithia[3.3](3,5)pyrdinophane (L¹) has been synthesized by a new method and characterized by ¹H NMR, which is used to form coordination complexes C₁₄H₁₄N₄O₆S₂Ni (I) by addition of Ni²⁺ cation and C₁₄H₁₄N₃O₃S₂Ag (II) by addition of Ag⁺ cation. 2,11,20-Trithia[3.3.3](3,5)pyridinophane (L²) and 2,11,20,29-tetrathia[3.3.3.3](3,5)pyridinophane (L³) have also been synthesized as by-products. Single-crystal X-ray analysis reveals that the conformation of the L¹ is syn(boat-chair), complexes I and II also adopt syn(boat-chair) (CIF files CCDC nos. 1400332 (I) and 700724 (II)). While in I, Ni(II) is coordinated with L¹ with two nitrogen and four oxygen atoms, in II, Ag(^I) is coordinated with L¹ by two nitrogen and two sulfur atoms came from four ligands. In complexes I and II, the formation of three-dimensional structure depends on π???π stacking and hydrogen bonds.     

Reactions of [(Me3Si)3CAlMe2] with substituted benzoic acids. Isolation of a rare organoalumoxane carboxylate

The reactivity of bulky tris(trimethylsilyl)methyl group substituted aluminum trialkyl [(Me₃Si)₃CAlMe₂·THF] (1) with a series of substituted benzoic acid derivatives has been investigated. An equimolar reaction of 4-methyl benzoic acid or 4-tert-butyl benzoic acid with 1 in toluene at 50 °C leads to the formation of cyclic dimeric aluminum carboxylates [(Me₃Si)₃CAl(Me)(μ-O₂CC₆H₄R)]₂ (R = Me 2; ^tBu 3). Reaction of 3,5-di-iso-propylsalicylic acid (H₂dipsa) with 1 leads to the exclusive isolation of a trimeric organoaluminum carboxylate [(Me₃Si)₃CAl(μ-dipsa)]₃ (4), in which each aluminum is bound to two carboxylates, a phenoxide, and an alkyl group and produce a 12-membered macrocycle. Deliberate, but controlled, introduction of water in the form of 3,5-di-tert-butyl salicylic acid monohydrate (H₂dtbsa·H₂O) in the reaction with 1 in toluene leads to the isolation of carboxylate [(Me₃Si)₃CAl(μ-O)(μ-Hdtbsa)}₂] (5) with a bicyclic structure. Compound 5 represents a rare example of an organoalumoxane carboxylate that simultaneously possesses alkyl, oxo, and carboxylate moieties on aluminum.     

Syntheses, structures, spectroscopic, electrochemical properties and DFT calculation of Ru(II)–thioarylazoimidazole complexes

The reaction of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazoles (SRaaiNR) (2a/2b) with Ru(II) has synthesized [Ru(SRaaiNR)₂](ClO₄)₂ (3a/3b) in 2-methoxyethanol. The reaction in methanol, however, has synthesized [Ru(SRaaiNR)(SRaaiNR)Cl](ClO₄) (4a/4b). The solid phase reaction of SRaaiNR and RuCl₃ on silica gel surface upon microwave irradiation has synthesized [Ru(SRaaiNR)(SaaiNR)](PF₆) (5a/5b) [SRaaiNR represents tridentate N,N′,S-chelator; SRaaiNR is N,N′-bidentate chelator where S does not coordinate and SaaiNR refers N,N′,S-chelator where S refers to thiolato binding]. The structural characterization of [Ru(SEtaaiNEt)(SEtaaiNEt)Cl](ClO₄) (4b) and [Ru(SEtaaiNEt)(SaaiNEt)](PF₆) (5b) has been confirmed by single crystal X-ray diffraction study. The IR, UV–Vis, and ¹H NMR spectral data also support the stereochemistry of the complexes. The complexes show metal oxidation, Ru(III)/Ru(II), and ligand reductions (azo/azo⁻, azo⁻/azo). The molecular orbital diagram has been drawn by density functional theory (DFT) calculation. Normal mode of analysis has been performed to correlate calculated and experimental frequencies of representative complexes. The electronic movement and assignment of electronic spectra have been carried out by TDDFT calculation both in gas and acetonitrile phase.     

Influence of geometric and electronic features of pyridine derivatives and triethylamine on the formation of a metal carboxylate core in reactions producing cadmium(<Emphasis Type="SmallCaps">ii</Emphasis>) pivalate complexes

The reaction products of [Cd(piv)₂] (piv is–O₂CBu^t) with isoquinoline (iqn), 2,4-lutidine (lut), phenanthridine (phend), 2,3-cyclododecenopyridine (cpy), and triethylamine (Et₃N) were synthesized and their structures were determined. The steric factors were found to play a more important role in cadmium(ii) pivalate complexes compared to 3d metal carboxylates in the +2 oxidation state. The reaction of [Cd(piv)₂] with isoquinoline produces only the mononuclear complex [Cd(piv)₂(iqn)₃] (1). The reaction of [Cd(piv)₂] with pyridine derivatives bearing a bulky substituent at the α position is accompanied by the formation of symmetrical dinuclear complexes of the composition [Cd₂(piv)₄(L)₂]. In the complexes with L = lut (2) or phend (3), the cadmium(ii) atoms are linked by two chelating-bridging carboxylate groups; in the complex with L = cpy (4), by four bidentate-bridging groups. The reaction of [Cd(piv)₂] with Et₃N in a solution of MeCN gives the centrosymmetric linear trinuclear complex [Cd₃(piv)₆(Et₃N)₂] (6); in a mixture of benzene and hexane, the ionic compound (HEt₃N)[Cd₂(piv)₅(H₂O)] (7). The crystal structures of all synthesized compounds were determined by X-ray diffraction.     

Synthesis and characterization of some novel cadmium(II) complexes with 3-hydroxypicolinic acid (3-OHpicH): Crystal and molecular structures of [CdI(3-OHpic)(3-OHpicH)(H2O)]2, [Cd(3-OHpic)2(H2O)2] and [Cd(3-OHpic)2]n

Cadmium(II) complexes of 3-hydroxypicolinic acid, namely [CdI(3-OHpic)(3-OHpicH)(H₂O)]₂ (1), [Cd(3-OHpic)₂(H₂O)₂] (2) and [Cd(3-OHpic)₂]_n (3) were prepared and characterized by spectroscopic methods (IR, NMR) and their molecular and crystal structures were determined by X-ray crystal structure analysis. Complexes 1 and 2 were prepared in similar reaction conditions using different cadmium(II) salts: cadmium(II) iodide and cadmium(II) acetate dihydrate, respectively, while 3 was prepared by recrystallization of 2 from N,N-dimethylformamide solution. Various coordination modes of 3-OHpicH in 1–3 were established in the solid state: bidentate N,O-chelated mode in 1 and 2, monodentate mode through the carboxylate O atom from zwitterionic ligand in 1 and bidentate N,O-chelated and bridging mode in 3. In the DMF solution of all prepared complexes, only monodentate mode of 3-OHpicH binding to cadmium(II) through the carboxylate O atom was established by ¹H, ¹³C, ¹⁵N and ¹¹³Cd NMR spectroscopy.     

Self-assembly of extended Schiff base amino acetate skeletons, 2-{[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}phenylpropionate and 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}phenylpropionate skeletons incorporating organotin(IV) moieties: Synthesis,spectroscopic characterization,crystal structures,and in vitro cytotoxic activity

The organotin(IV) compounds, [Ph₃SnL¹H]_n · nCCl₄ (1), [Me₂SnL²(OH₂)] (2), [ⁿBu₂SnL²] (3), [Ph₂SnL²]_n (4), [Ph₃SnL²H]_n (5) and [Ph₃SnL³H]_n (7) (L¹ = 2-{[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}phenylpropionate and L²⁻³ = 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}phenylpropionate), were synthesized by treating the appropriate organotin(IV) chloride(s) with the potassium salt of the ligand in a suitable solvent, while [ⁿBu₂SnL³(OH₂)] (6) was obtained by reacting the acid form of L³ (generated in situ) with ⁿBu₂SnO. These complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS, IR and ^119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of 1 and 4–7 were determined. The crystal structures of complexes 1, 5 and 7 reveal that the complexes exist as polymeric chains in which the L-bridged Sn-atoms adopt a trans-R₃SnO₂ trigonal bipyramidal configuration with R groups in the equatorial positions and the axial locations occupied by a carboxylate oxygen from the carboxylate ligand and the alcoholic or phenolic oxygen of the next carboxylate ligand in the chain. The carboxylate ligands coordinate in the zwitterionic form with the alcoholic/phenolic proton moved to the nearby nitrogen atom. A polymeric zig-zag cis-bridged chain structure is observed for 4, without considering the weak Sn⋯O interaction, the Sn-atom having a slightly distorted trigonal bipyramidal coordination geometry with the two O atoms of the tridentate amino propionate ligand in axial positions. On the other hand, the structure of 6 reveals a monomeric molecule in which the Sn-atom has a distorted octahedral coordination geometry involving the tridentate carboxylate ligand, two n-butyl ligands occupying trans-positions and one water ligand. The in vitro cytotoxic activity of triphenyltin(IV) compounds, viz., 1, 5 and 7 against WIDR, M19 MEL, A498, IGROV, H226, MCF7 and EVSA-T human tumor cell lines are also reported.     

邻苯二甲酸单甲酯双核铜配合物的强反铁磁性和磁构关联研究

以邻苯二甲酸单甲酯(mMP)为配体合成了一个新的双核铜配位化合物[Cu₂(mMP)₂(H₂O)₂]₂·2H₂O (1), 并通过元素分析、红外光谱和X射线单晶衍射等方法对化合物晶体结构进行了表征. 化合物1通过四羧酸桥联的方式形成了桨轮状双金属笼结构. 每个Cu(II)离子采用四方单锥的五配位构型, 其中四个氧原子来自于四个不同的邻苯二甲酸单甲酯配体, 轴向位置上的氧原子则来自于水分子. 配位水分子和溶剂水分子与配体中未配位的氧原子形成了分子间氢键, 并进一步形成三维网络结构. 磁性数据显示双核铜内为强的反铁磁交换作用, 磁耦合作用常数2J=-324 cm^-1. 通过与相关双核铜化合物的对比, 详细分析了化合物的磁构关联并讨论了羧酸类双核铜中强反铁磁性作用的结构因素. 研究表明, 影响羧酸类双核铜强反铁磁性作用的主要结构因素是配体中桥联双核铜的O－C－O部分的电子结构.     

New aqua rhenium oxocomplex; synthesis,characterization, thermal studies,DFT calculations and catalytic oxidations

The aqua rhenium oxocomplex [ReO(OH)(H₂O)₄]^2? (1) has been prepared and characterized by spectroscopy, thermogravimetry, and elemental analysis and its reactivity towards triphenylphosphine has been evaluated. Complex (1) acts as a catalyst precursor in the presence of molecular oxygen for the oxidation of PPh₃ to OPPh₃. This proceeds through complex intermediates like [Re(PPh₃)_n]³⁺ (2), and [ReO(PPh₃)_n]³⁺ (3). The newly prepared complex (1) was also employed as catalyst for catalytic oxidation of cyclohexane. The geometry of [ReO(OH)(H₂O)₄]^2? has also been optimized in the singlet state by the DFT method with B3LYP level of theory.     

Synthesis, crystal structures, and properties of inorganic-organic hybrid complexes constructed from copper(II) macrocyclic fragment

Reaction of a macrocyclic copper(II) complex [Cu(L)](ClO₄)₂ · 3H₂O (I) (L = 1,3,10,12,16,19-hexaazatetracyclotetracosane) with a hexapod carboxylate ligand H₆TTHA (H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid) and a tripod carboxylate ligand H₃TATB (H₃TATB = 4,4′,4″-S-triazine-2,4,6-triyl-tribenzoic acid) yielded two mononuclear copper(II) complexes [Cu(L)][H₄TTHA] · 4H₂O (II) and [Cu(L)][HTATB] · 4H₂O (III). The complexes I–III have been structurally characterized. The crystal structures of complexes II and III show the copper(II) ion has a distorted pentacoordinate square-pyramidal geometry with two secondary and two tertiary amines from the macrocyclic complex [Cu(L)]²⁺ and one oxygen atom from the carboxylate ligand group at the axial position. The UV-Vis spectra are utilized to discuss the hydrolysis of the complex II.     

Syntheses,structures and properties of copper(II) complexes with thiophene-2,5-dicarboxylic acid (H2Tda) and nitrogen-containing ligands

Five copper(II) complexes with thiophene-2,5-dicarboxylic acid (H₂Tda): Cu(Tda)(H₂O)⋅(H₂O)₂ (1), Cu(Tda)(im)₂⋅(H₂O) (2), Cu(Tda)(im)₄ (3), [Cu(Tda)(py)₂]_n (4) and [Cu(Tda)(bipy)(H₂O)]_n⋅n[Cu(Tda)(bipy)(H₂O)₂]⋅2nH₂O (5) (im=imidazole, py=pyridine and bipy=2,2′-bipyridine) have been synthesised and their spectroscopic and thermal properties investigated. Three of them (3, 4 and 5) are structurally characterised and the Cu atom is in five coordinate, distorted square pyramidal environments. The thiophene-2,5-dicarboxylate molecule is monodentate in 3 in which the molecular structure is stabilised by intermolecular hydrogen bonding involving two of the four non-coordinated nitrogen atoms of the imidazole ligands and carboxylate groups from adjacent Tda²⁻. In 4 the thiophene-2,5-dicarboxylate ion is bridging tridentate and bonded to three copper atoms to form a chain polymer with alternating 16-membered ring bridged by two Tda²⁻ and an 8-membered ring bridged by two carboxylates. Complex 5 comprises discrete [Cu(Tda)(bipy)(H₂O)₂] (5a), one dimensional zig–zag chain of [Cu(Tda)(bipy)(H₂O)]_n (5b) and water molecules of crystallization. The thiophene-2,5-dicarboxylate molecule is monodentate in 5a and involved in intermolecular stacking interactions with 2,2'-bipyridine rings, and bidentate in 5b to bridge [Cu(bipy)(H₂O)] to form a one dimensional zig–zag chain.