Metallkomplexe naphthyl‐substituierter Thioharnstoffderivate

Metal Complexes of Naphthyl‐substituted Thiourea Derivatives The thiourea derivative N, N‐diethyl‐N′‐2‐naphthoylthiourea ( 1 ) and three N‐(dialkylaminothiocarbonyl)‐N′‐(1‐naphthyl)‐arylamidines ( 2 ‐ 4 ) have been synthesized and Cu^II‐, Ni^II‐ and Pd^II‐complexes of them have been prepared. According to the X‐ray structure analyses 1 with Cu^II and Ni^II under deprotonation forms neutral bis‐chelates of nearly square‐planar coordination with a cis arrangement of the O and S ligator atoms. Using their N and S atoms in 1, 3 position as ligators, 2 ‐ 4 in deprotonated form coordinate to Cu^II and Pd^II as neutral bis‐chelates, in the case of Cu^II with a distorted tetrahedral coordination. Pd^II is coordinated square planar and has, probably due to the spatial influence of the 1‐naphthyl groups, a trans arrangement of the N and S ligator atoms.     

Synthese,Strukturen, NMR‐ und EPR‐Untersuchungen der binuklearen Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(selenoureato))‐Komplexe des NiII und CuII

Synthesis, Structures, NMR and EPR Investigations of Binuclear Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(selenoureato)) Complexes of Ni^II and Cu^II The synthesis of binuclear Cu^II and Ni^II complexes of the quadridentate ligand N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(selenourea) and their crystal structures are reported. The complexes crystallize monoclinic, P2₁/c (Z = 2). In the EPR spectra of the binuclear Cu^II complex exchange‐coupled Cu^II‐Cu^II pairs were observed. In addition the signals of a mononuclear Cu^II species are observed what will be explained with the assumption of an equilibrium between the binuclear Cu^II‐complex (Cu^II‐Cu^II pairs) and oligomeric complexes with “isolated” Cu^II ions. Detailed ¹³C and ⁷⁷Se NMR investigations on the ligand and the Ni^II complex allow an exact assignment of all signals of the heteroatoms.     

Poly[[aqua‐μ3‐2,2‐dimethylmalonato‐copper(II)] monohydrate] and poly[aqua‐μ3‐2,2‐dimethylmalonato‐copper(II)]

The coordination mode of the dimethylmalonate ligand in the two title Cu^II complexes, {[Cu(C₅H₃O₄)(H₂O)]·H₂O}_n, (I), and [Cu(C₅H₃O₄)(H₂O)]_n, (II), is the same, with chelated six‐membered, bis‐monodentate and bridging bonding modes. However, the coordination environment of the Cu^II atoms, the connectivity of their metal–organic frameworks and their hydrogen‐bonding interactions are different. Complex (I) has a perfect square‐pyramidal Cu^II environment with the aqua ligand in the apical position, and only one type of square grid consisting of Cu^II atoms linked via carboxylate bridges to three dimethylmalonate ligands, with weak hydrogen‐bond interactions within and between its two‐dimensional layers. Complex (II) has a coordination geometry that is closer to square pyramidal than trigonal bipyramidal for its Cu^II atoms with the aqua ligand now in the basal plane. Its two‐dimensional layer structure comprises two alternating grids, which involve two and four different dimethylmalonate anions, respectively. There are strong hydrogen bonds only within its layers.     

A one‐dimensional coordination polymer of 5‐[(imidazol‐1‐yl)methyl]benzene‐1,3‐dicarboxylic acid with CuII cations

5‐[(Imidazol‐1‐yl)methyl]benzene‐1,3‐dicarboxylic acid (H₂L) was synthesized and the dimethylformamide‐ and dimethylacetamide‐solvated structures of its adducts with Cu^II, namely catena‐poly[[copper(II)‐bis[μ‐3‐carboxy‐5‐[(imidazol‐1‐yl)methyl]benzoato]] dimethylformamide disolvate], {[Cu(C₁₂H₉N₂O₄)₂]·2C₃H₇NO}_n, (I), and catena‐poly[[copper(II)‐bis[μ‐3‐carboxy‐5‐[(imidazol‐1‐yl)methyl]benzoato]] dimethylacetamide disolvate], {[Cu(C₁₂H₉N₂O₄)₂]·2C₄H₉NO}_n, (II), the formation of which are associated with mono‐deprotonation of H₂L. The two structures are isomorphous and isometric. They consist of one‐dimensional coordination polymers of the organic ligand with Cu^II in a 2:1 ratio, [Cu(μ‐HL)₂]_n, crystallizing as the dimethylformamide (DMF) or dimethylacetamide (DMA) disolvates. The Cu^II cations are characterized by a coordination number of six, being located on centres of crystallographic inversion. In the polymeric chains, each Cu^II cation is linked to four neighbouring HL⁻ ligands, and the organic ligand is coordinated via Cu—O and Cu—N bonds to two Cu^II cations. In the corresponding crystal structures of (I) and (II), the coordination chains, aligned parallel to the c axis, are further interlinked by strong hydrogen bonds between the noncoordinated carboxy groups in one array and the coordinated carboxylate groups of neighbouring chains. Molecules of DMF and DMA (disordered) are accommodated at the interface between adjacent polymeric assemblies. This report provides the first structural evidence for the formation of coordination polymers with H₂Lvia multiple metal–ligand bonds through both carboxylate and imidazole groups.     

Bis{1‐n‐hex­yl‐3‐meth­yl‐4‐[1‐(phenyl­imino)prop­yl]‐1H‐pyrazol‐5‐olato}­copper(II): a new copper(II) complex with a chelating alkyl­pyrazolone‐based enamine

The title compound, [Cu(C₁₉H₂₆N₃O)₂], is the first reported complex of the alkyl­pyrazolone‐derived ligand 1‐n‐hexyl‐3‐methyl‐4‐[1‐(phenylimino)propyl]‐1H‐pyrazol‐5(4H)‐one. The most notable feature is the imine–enol character presented by the ligand due to coordination, in spite of its enamine–ketone structure in the free state. The ligand chelates through N and O atoms, resulting in a square‐planar coordination around the Cu^II atom, which lies on an inversion centre.     

The Coordination Chemistry of the Versatile Ligand Bis(2‐pyridylthio)methane

Bis(2‐pyridylthio)methane [bpytm, (pyS)₂CH₂] and complexes of this ligand with Zn^II, Hg^II, Cu^I, and Ag^I have been prepared and characterised by elemental analysis, by IR, Raman and ¹H and ¹³C NMR spectroscopy, and by X‐ray diffractometry. The ligand is N, N′‐didentate in the Zn^II complexes; N‐monodentate in one Hg^II complex and N, N′‐bis(monodentate) in the other; N‐mono‐N′, S‐didentate in the Cu^I complex; and N, S′‐bis(mono)‐N′, S‐didentate in the Ag^I complex. The structural parameters of the ligand in each coordination mode are compared with those of the free ligand and those of the triiodide salt of the protonated ligand.     

Synthesis,Characterization, DNA‐binding Properties,and ­Antioxidant Activity of a Copper(II) Complex with 1, 3‐Bis­(1‐allaylbenzimidazol‐2‐yl)‐2‐oxopropane

A new complex of copper(II) picrate (pic) with 1, 3‐bis(1‐allaylbenzimidazol‐2‐yl)‐2‐oxopropane (aobb), with the composition [Cu(aobb)₂](pic)₂, was synthesized and characterized. The crystal structure of the copper(II) complex revealed that the coordination environment around the central copper(II) atom is a distorted octahedral arrangement. Electronic absorption spectroscopy, ethidium bromide displacement experiments and viscosity measurements indicate that the ligand and the Cu^II complex can strongly bind to calf thymus DNA, presumably by an intercalation mechanism. Furthermore, the antioxidant activity of the Cu^II complex was determined by superoxide and hydroxyl radical scavenging method in vitro, which indicate that the Cu^II complex has the activity to suppress OH ^· and O₂ ^{· –}.     

Disentangling steric and electronic factors in monomeric bis(2‐bromo‐4‐chloro‐6‐{[(2‐hydroxyethyl)imino]methyl}phenolato‐κ2N,O)copper(II)

The title compound, [Cu(C₉H₈BrClNO₂)₂], is a square‐planar complex. The potentially tridentate dibasic 2‐bromo‐4‐chloro‐6‐{[(2‐hydroxyethyl)imino]methyl}phenolate ligand coordinates in a trans‐bis fashion to the Cu^II centre via the imine N and phenolate O atoms. The Cu^II atom lies on the centre of inversion of the molecule. The potentially coordinating hydroxyethyl group remains protonated and uncoordinated, taking part in intermolecular hydrogen bonds with vicinal groups, leading to the formation of a two‐dimensional hydrogen‐bond network with sheets parallel to the (10) plane. Substituent effects on the crystal packing and coordination modes of the ligand are discussed.     

Synthese,Struktur und EPR‐Untersuchungen von binuklearen Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))‐Komplexen des CuII,NiII, ZnII,CdII und PdII

Synthesis, Structure and EPR Investigations of binuclear Bis(N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato)) Complexes of Cu^II, Ni^II, Zn^II, Cd^II and Pd^II The synthesis of binuclear Cu^II‐, Ni^II‐, Zn^II‐, Cd^II‐ and Pd^II‐complexes of the quadridentate ligand N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and the crystal structures of the Cu^II‐ and Ni^II‐complexes are reported. The Cu^II‐complex crystallizes in two polymorphic modifications: triclinic, (Z = 1) and monoclinic, P2₁/c (Z = 2). The Ni^II‐complex was found to be isostructural with the triclinic modification of the copper complex. The also prepared Pd^II‐, Zn^II‐ and Cd^II‐complexes could not be characterized by X‐ray analysis. However, EPR studies of diamagnetically diluted Cu^II/Pd^II‐ and Cu^II/Zn^II‐powders show axially‐symmetric g and A ^Cu tensors suggesting a nearly planar co‐ordination within the binuclear host complexes. Diamagnetically diluted Cu^II/Cd^II powder samples could not be prepared. In the EPR spectra of the pure binuclear Cu^II‐complex exchange‐coupled Cu^II‐Cu^II pairs were observed. According to the large Cu^II‐Cu^II distance of about 7,50Å a small fine structure parameter D = 26·10^?4 cm^?1 is observed; T‐dependent EPR measurements down to 5 K reveal small antiferromagnetic interactions for the Cu^II‐Cu^II dimer. Besides of the dimer in the EPR spectra the signals of a mononuclear Cu^II species are observed whose concentration is T‐dependent. This observation can be explained assuming an equilibrium between the binuclear Cu^II‐complex (Cu^II‐Cu^II pairs) and oligomeric complexes with “isolated” Cu^II ions.     

Synthesis,Crystal Structures,and Properties of Copper(II), Zinc(II), and Cadmium(II) Coordination Polymers Based on 5‐Nitro‐isophthalate and 1,2‐(2‐Pyridyl)‐1,2,4‐triazole

Three coordination polymers, namely {[Cu(5‐nipa)(L²²)](H₂O)₂}_n ( 1 ), [Zn(5‐nipa)(L²²)(H₂O)]_n ( 2 ), and {[Cd₂(5‐nipa)₂(L²²)(H₂O)₃](H₂O)_3.6}_n ( 3 ), were prepared under similar synthetic method based on 1,2‐(2‐pyridyl)‐1,2,4‐triazole (L²²) and ancillary ligand 5‐nitro‐isophthalic acid (5‐H₂nipa) with Cu^II, Zn^II, and Cd^II perchlorate, respectively. All the complexes were characterized by IR spectroscopy, elemental analysis, and powder X‐ray diffraction (PXRD) patterns. Single‐crystal X‐ray diffraction indicates that complexes 1 and 2 show similar 1D chain structures, whereas complex 3 exhibits the 2D coordination network with hcb topology. The central metal atoms show distinct coordination arrangements ranging from distorted square‐pyramid for Cu^II in 1 , octahedron for Zn^II in 2 , to pentagonal‐bipyramid for Cd^II in 3 . The L²² ligand adopts the same (η³,μ₂) coordination fashion in complexes 1 – 3 , while the carboxyl groups of co‐ligand 5‐nipa^2– adopt monodentate fashion in 1 and 2 and bidentate chelating mode in 3 . These results indicate that the choice of metal ions exerts a significant influence on governing the target complexes. Furthermore, thermal stabilities of complexes 1 – 3 and photoluminescent properties of 2 and 3 were also studied in the solid state.     

[N,N′‐Bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminato]­nickel(II) and [N,N′‐bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminato]copper(II)

In the title compounds, {2,2′‐[2,2‐di­methyl‐1,3‐propane­diyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴N,N′,O,O′}nickel(II), [Ni(C₁₉H₂₀N₂O₂)], and {2,2′‐[2,2‐di­methyl‐1,3‐propane­diyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴N,N′,O,O′}copper(II), [Cu(C₁₉H₂₀N₂O₂)], the Ni^II and Cu^II atoms are coordinated by two iminic N and two phenolic O atoms of the N,N′‐bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminate (SALPD^2?, C₁₇H₁₆N₂O₂^2?) ligand. The geometry of the coordination sphere is planar in the case of the Ni^II complex and distorted towards tetrahedral for the Cu^II complex. Both complexes have a cis configuration imposed by the chelate ligand. The dihedral angles between the N/Ni/O and N/Cu/O coordination planes are 17.20 (6) and 35.13 (7)°, respectively.     

Di‐μ‐chlorido‐bis({2‐[1‐(2‐pyridylethylimino)ethyl]pyrrolato‐κ3N,N′,N′′}copper(II))

The title compound, [Cu₂(C₁₃H₁₄N₃)₂Cl₂], is a neutral dimeric copper(II) complex. The two Cu^II atoms are asymmetrically bridged by two chloride ions. Each Cu^II atom is also bound to the three N atoms of a deprotonated tridentate Schiff base ligand, giving a distorted square‐pyramidal N₃Cl₂ coordination environment overall. The dinuclear complex lies across an inversion centre in the space group P. This work demonstrates the effect of ligand flexibility and steric constraints on the structures of copper(II) complexes.     

catena‐Poly[hexaaquamagnesium(II) [bis(μ3‐5‐nitro‐2‐oxidoisophthalato)dicopper(II)] dihydrate]

In the centrosymmetric dinuclear anions of the title bimetallic complex, {[Mg(H₂O)₆][Cu₂(C₈H₂NO₇)₂]·2H₂O}_n, each Cu^II ion is strongly coordinated by four O atoms in a distorted square‐planar geometry. Two of these O atoms belong to phenolate groups and the other two to carboxylate groups from 5‐nitro‐2‐oxidoisophthalate (L1) trianions, derived from 5‐nitrobenzene‐1,2,3‐tricarboxylic acid (O₂N–H₃L). The phenolate O atoms bridge the two Cu^II ions in the anion. In addition, each Cu^II cation interacts weakly with a symmetry‐related carboxylate O atom of an adjacent L1 ligand, giving a square‐pyramidal coordination geometry. The copper residue forms a ladder‐like linear coordination polymer via L1 ligands. The [Mg(H₂O)₆]²⁺ cations sit on centres of inversion. The polymeric anions, cations and free water molecules are self‐assembled into a three‐dimensional supramolecular network via O—H...O hydrogen bonds.     

Copper(II) and Sodium(I) Complexes based on 3,7‐Diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide: Synthesis,Characterization, and Catalytic Activity

The reaction of 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane (DAPTA) with metal salts of Cu^II or Na^I/Ni^II under mild conditions led to the oxidized phosphane derivative 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide (DAPTA=O) and to the first examples of metal complexes based on the DAPTA=O ligand, that is, [Cu^II(μ‐CH₃COO)₂(κO‐DAPTA=O)]₂ ( 1 ) and [Na(1κOO′;2κO‐DAPTA=O)(MeOH)]₂(BPh₄)₂ ( 2 ). The catalytic activity of 1 was tested in the Henry reaction and for the aerobic 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO)‐mediated oxidation of benzyl alcohol. Compound 1 was also evaluated as a model system for the catechol oxidase enzyme by using 3,5‐di‐tert‐butylcatechol as the substrate. The kinetic data fitted the Michaelis–Menten equation and enabled the obtainment of a rate constant for the catalytic reaction; this rate constant is among the highest obtained for this substrate with the use of dinuclear Cu^II complexes. DFT calculations discarded a bridging mode binding type of the substrate and suggested a mixed‐valence Cu^II/Cu^I complex intermediate, in which the spin electron density is mostly concentrated at one of the Cu atoms and at the organic ligand.     

A two‐dimensional mixed‐valence CuII/CuI coordination polymer constructed from 2‐(pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylate

Coordination polymers are a thriving class of functional solid‐state materials and there have been noticeable efforts and progress toward designing periodic functional structures with desired geometrical attributes and chemical properties for targeted applications. Self‐assembly of metal ions and organic ligands is one of the most efficient and widely utilized methods for the construction of CPs under hydro(solvo)thermal conditions. 2‐(Pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylate (HPIDC²⁻) has been proven to be an excellent multidentate ligand due to its multiple deprotonation and coordination modes. Crystals of poly[aquabis[μ₃‐5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylato‐κ⁵N¹,O⁵:N³,O⁴:N²]copper(II)dicopper(I)], [Cu^IICu^I₂(C₁₀H₅N₃O₄)₂(H₂O)]_n, (I), were obtained from 2‐(pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PIDC) and copper(II) chloride under hydrothermal conditions. The asymmetric unit consists of one independent Cu^II ion, two Cu^I ions, two HPIDC²⁻ ligands and one coordinated water molecule. The Cu^II centre displays a square‐pyramidal geometry (CuN₂O₃), with two N,O‐chelating HPIDC²⁻ ligands occupying the basal plane in a trans geometry and one O atom from a coordinated water molecule in the axial position. The Cu^I atoms adopt three‐coordinated Y‐shaped coordinations. In each [CuN₂O] unit, deprotonated HPIDC²⁻ acts as an N,O‐chelating ligand, and a symmetry‐equivalent HPIDC²⁻ ligand acts as an N‐atom donor via the pyridine group. The HPIDC²⁻ ligands in the polymer serve as T‐shaped 3‐connectors and adopt a μ₃‐κ²N,O:κ²N′,O′:κN′′‐coordination mode, linking one Cu^II and two Cu^I cations. The Cu cations are arranged in one‐dimensional –Cu1–Cu2–Cu3– chains along the [001] direction. Further crosslinking of these chains by HPIDC²⁻ ligands along the b axis in a –Cu2–HPIDC²⁻–Cu3–HPIDC²⁻–Cu1– sequence results in a two‐dimensional polymer in the (100) plane. The resulting (2,3)‐connected net has a (12³)₂(12)₃ topology. Powder X‐ray diffraction confirmed the phase purity for (I), and susceptibilty measurements indicated a very weak ferromagnetic behaviour. A thermogravimetric analysis shows the loss of the apical aqua ligand before decomposition of the title compound.     

Synthese,Strukturen und X‐/Q‐Band‐EPR‐Untersuchungen von N,N‐Diethyl‐N′‐3,5‐di(trifluormethyl)benzoylthioureato‐Komplexen des CuII,NiII und PdII sowie EPR‐spektroskopische Charakterisierung eines CuII‐CuII‐Dimers

The synthesis and the structures of (i) the ligand N,N‐Diethyl‐N′‐3,5‐di(trifluoromethyl)benzoylthiourea HEt₂dtfmbtu and (ii) the Ni^II and Pd^II complexes of HEt₂dtfmbtu are reported. The ligand coordinates bidendate forming bis chelates. The Ni^II and the Pd^II complexes are isostructural. The also prepared Cu^II complex could not be characterized by X‐ray analysis. However, the preparation of diamagnetically diluted powders Cu/Ni(Et₂dtfmbtu)₂ and Cu/Pd(Et₂dtfmbtu)₂ suitable for EPR studies was successful. The EPR spectra of the Cu/Ni and Cu/Pd systems show noticeable differences for the symmetry of the CuS₂O₂ unit in both complexes: the Cu/Pd system is characterized by axially‐symmetric g< and A ^cu tensors; for the Cu/Ni system g and A ^Cu have rhombic symmetry. EPR studies on frozen solutions of the Cu^II complex show the presence of a Cu^II‐Cu^II dimer which is the first observed for Cu^II acylthioureato complexes up to now. The parameters of the fine structure tensor were used for the estimation of the Cu^II‐Cu^II distance.     

A square‐pyramidal copper(II) complex with strong intramolecular hydrogen bonds: diaqua(N,N′‐dimethylformamide‐κO)bis[2‐(diphenylphosphoryl)benzoato‐κO]copper(II)

In the title Cu^II complex, [Cu(C₁₉H₁₄O₃P)₂(C₃H₇NO)(H₂O)₂], the molecule is bisected by a twofold axis relating the two 2‐(diphenylphosphoryl)benzoate (ODPPB) ligands. The asymmetric unit consists of a Cu^II metal centre on the symmetry axis, an ODPPB ligand, one water ligand and one dimethylformamide (DMF) ligand (disordered around the twofold axis). The Cu^II ion has fivefold coordination provided by two carboxylate O atoms from two ODPPB ligands, two O atoms from two coordinated water molecules and another O atom from a (disordered) DMF molecule, giving a CuO₅ square‐pyramidal coordination geometry. The ODPPB ligand adopts a terminal monocoordinated mode with two free O atoms forming two strong intramolecular hydrogen bonds with the coordinated water molecules, which may play a key role in the stability of the molecular structure, as shown by the higher release temperature for the coordinated water molecules than for the coordinated DMF molecule. The optical absorption properties of powder samples of the title compound have also been studied.     

Synthesis,Crystal Structure,DNA‐binding Properties and Antioxidant Activity of a Copper(II) Complex with Naphthalimide Schiff Base

The Schiff N‐allylamine‐4‐(ethylenediamine‐5‐methylsalicylidene)‐1,8‐naphthalimide (H₂L) and its copper(II) complex, [Cu(HL)₂] · 0.5DMF, were synthesized and characterized. The crystal structure of the Cu^II complex reveals a slightly distorted square‐planar arrangement provided by two N and O donors from two deprotonated ligands. In addition, the DNA‐binding properties of the ligand and Cu^II complex were investigated by fluorescence spectra, electronic absorption, and viscosity measurements. The experimental studies of the DNA‐binding properties indicated that the ligand and Cu^II complex reacted with DNA via intercalation binding mode, and binding affinity for DNA takes the order: ligand > Cu^II complex. The antioxidant assay in vitro suggested that both exhibited potential intensely antioxidant properties, and the ligand is more effective than its Cu^II complex.     

Homo‐ and Heteronuclear Compounds with a Symmetrical Bis‐hydrazone Ligand: Synthesis,Structural Studies,and Luminescent Properties

Nine new coordination compounds have been synthesized by the reaction of salts of bivalent metal ions (a=Zn^II, b=Cu^II, c=Ni^II, d=Co^II) with the bis(benzoylhydrazone) derivative of 4,6‐diacetylresorcinol (H₄L). Three kinds of complexes have been obtained: homodinuclear compounds [M₂(H₂L)₂]?nH₂O ( 1 a , 1 b , 1 c , and 1 d ), homotetranuclear compounds [M₄(L)₂]?n(solv) ( 2 a and 2 c ), and heterotetranuclear compounds [Zn₂M₂(L)₂]?n(solv) ( 2 ab , 2 ac , and 2 ad ). The structures of the free ligand H₄L?2 DMSO and its complexes [Zn₂(H₂L)₂(DMSO)₂] ( 1 a* ), [Zn₄(L)₂(DMSO)₆] ( 2 a* ), and [Zn_0.45Cu_3.55(L)₂(DMSO)₆]?2 DMSO ( 2 ab* ) were elucidated by single‐crystal X‐ray diffraction. The ligand shows luminescence properties and its fluorimetric behavior towards M^II metals (M=Zn, Cu, Ni and Co) has been studied. Furthermore, the solid‐state luminescence properties of the ligand and compounds have been determined at room temperature. ¹H NMR spectroscopic monitoring of the reaction of H₄L with Zn^II showed the deprotonation sequence of the OH/NH groups upon metal coordination. Heteronuclear reactions have also been monitored by using ESI‐MS and spectrofluorimetric techniques.     

Copper(II) Halide Complexes with 1‐tert‐Butyl‐1H‐1,2,4‐triazole and 1‐tert‐Butyl‐1H‐tetrazole

1‐tert‐Butyl‐1H‐1,2,4‐triazole (tbtr) was found to react with copper(II) chloride or bromide to give the complexes [Cu(tbtr)₂X₂]_n and [Cu(tbtr)₄X₂] (X = Cl, Br). 1‐tert‐Butyl‐1H‐tetrazole (tbtt) reacts with copper(II) bromide resulting in the formation of the complex [Cu₃(tbtt)₆Br₆]. The obtained crystalline complexes as well as free ligand tbtr were characterized by elemental analysis, IR spectroscopy, thermal and X‐ray analyses. For free ligand tbtr, ¹H NMR and ¹³C NMR spectra were also recorded. In all the complexes, tbtr and tbtt act as monodentate ligands coordinated by Cu^II cations via the heteroring N⁴ atoms. The triazole complexes [Cu(tbtr)₂Cl₂]_n and [Cu(tbtr)₂Br₂]_n are isotypic, being 1D coordination polymers, formed at the expense of single halide bridges between neighboring copper(II) cations. The isotypic complexes [Cu(tbtr)₄Cl₂] and [Cu(tbtr)₄Br₂] reveal mononuclear centrosymmetric structure, with octahedral coordination of Cu^II cations. The tetrazole compound [Cu₃(tbtt)₆Br₆] is a linear trinuclear complex, in which neighboring copper(II) cations are linked by single bromide bridges.