Copper(II) Supramolecular Complex: Synthesis,Crystal Structure,and Electrochemical Property

A novel complex {Cu(Bobb)₂](pic)₂}₂ [pic = picrate anion, Bobb = 1,3‐bis(1‐benzylbenzimidazol‐2‐yl)‐2‐oxopropane] was synthesized and characterized by means of elemental analyses and electrical conductivity. The crystal structure of the copper complex has been determined by single‐crystal X‐ray diffraction. A study of the electrochemistry of the title compound was carried out by using cyclic voltammetry. It revealed that the copper complex exhibits a quasi‐reversible redox process. The X‐ray structure of the above complex shows that the unit cell consists of two centrosymmetric, crystallographically independent molecules, in which the copper(II) ions have the same coordination environment and should be described as distorted octahedron. The complex is formed of { ··· Cu(2) ··· Cu(1) ··· Cu(1) ··· }_∞ supramolecular configuration by π ··· π stacking interactions between the benzimidazole rings. The complex was also identified by IR and electronic spectroscopy.     

New Saccharinato/Ammonia Complexes of Nickel(II) and Zinc(II). A Structural and Spectroscopic Study

Two new saccharinate/NH₃ complexes of composition [Ni(sac)₂(NH₃)₄] and [Zn(sac)₂(NH₃)₂] were obtained and their crystal structures determined by single crystal X‐ray diffractometry. The elongated octahedral Ni^II complex crystallizes in the monoclinic P2₁/c space group with Z = 2 whereas the tetrahedral Zn^II complex is triclinic (space group and Z = 2). For [Ni(sac)₂(NH₃)₄] the magnetic moment and electron absorption spectrum were obtained and discussed. The infrared spectra of both complexes were also recorded and briefly commented.     

Synthesis,Crystal Structure,and Spectroscopic Characterization of Na5[NiO2][CO3], containing the Linear [NiO2]3– Group with Monovalent Nickel

For the first time ruby‐red single crystals and powder samples of Na₅[NiO₂][CO₃] were obtained via a redox reaction between nickel metal and CdO in the presence of Na₂O and Na₂CO₃ (molar ratios of CdO : Na₂O : Na₂CO₃ equal 1 : 3 : 2). The crystal structure has been refined from single crystal X‐ray diffraction data at 170 K (tetragonal, P4/mmm, a = 462.7(1) pm, c = 830.5(2) pm) and at 293 K (a = 462.35(7) pm, c = 830.9(1) pm). Na₅[NiO₂][CO₃] is the first example of an alkaline‐rich transition metal oxide with two different oxoanions, [NiO₂]^3– and [CO₃]^2–, coexisting in one compound. The electronic spectrum of Na₅[NiO₂][CO₃] has been measured between 4000 and 25000 cm^–1. Two d‐d‐transitions of the linear [NiO₂]^3– complex (d⁹) are observed at 5870 cm^–1 and 11850 cm^–1 and analysed using the angular overlap model. MIR and FIR spectra give evidence for the [CO₃]^2– anion present in the structure.     

Crystal Structure and Spectroscopic Properties of trans‐Dibromidobis(propane‐1, 3‐diamine)chromium(III) Perchlorate

The structure of trans‐[Cr(tn)₂Br₂]ClO₄ (tn = propane‐1, 3‐diamine) has been determined by a single‐crystal X‐ray diffraction study at 100 K. The complex crystallizes in the space group P$\bar{1}$ of the triclinic system with two mononuclear formula units in a cell of dimensions a = 6.8220(4), b = 8.86199(9), c = 12.6644(8) Å and α = 77.859(7)°, β = 81.765(6)°, and γ = 77.764(7)°. The chromium atom is in a slightly distorted octahedral environment coordinated by four nitrogen atoms of two tn ligands and two bromine atoms in trans positions. The two six‐membered chelate rings in the complex cations are oriented in an anti chair‐chair conformation with respect to each other. The mean Cr–N(tn) and Cr–Br bonds are 2.093(3) and 2.4681(4) Å, respectively. The crystal packing is stabilized by hydrogen bonds. The infrared and electronic absorption spectral properties are consistent with the result of X‐ray crystallography. It is confirmed that the nitrogen atoms of the tn ligand are strong σ‐donors, but the bromido ligands have weak σ‐ and π‐donor properties toward the chromium(III) ion.     

Synthesis,Crystal Structure,and Characterization of Two Novel One‐ and Two‐Dimensionally Polymeric Copper(II) Phosphonoacetates

Blue single crystals of Cu[μ₂‐OOC(CH₂)PO₃H] · 2H₂O ( 1 ) and Cu_1.5[μ₃‐OOC(CH₂)PO₃] · 5H₂O ( 2 ) were prepared in aqueous solution. In compound 1 [space group C2/c (no. 15) with a = 1623.3(2), b = 624.0(1), c = 1495.5(2) pm, β = 122.45(1)°], Cu is coordinated by three oxygen atoms stemming from the hydrogenphosphonoacetate dianion and three water molecules to form a distorted octahedron. The Cu–O bonds range from 190.4(3) to 278.5(3) pm. The connection between the Cu²⁺ cations and the hydrogenphosphonoacetate dianions leads to a two‐dimensional structure with layers parallel to (101). The layers are linked by hydrogen bonds. In compound 2 [space group P1 (no. 2) with a = 608.2(1), b = 800.1(1), c = 1083.6(1) pm, α = 94.98(1)°, β = 105.71(1)°, γ = 109.84(1)°], two crystallographically independent Cu²⁺ cations are coordinated in a square pyramidal and an octahedral fashion, respectively. The Cu–O bonds range from 192.9(2) to 237.2(2) pm. The coordination of the phosphonoacetate trianion to Cu(1) results in infinite polyanionic chains parallel to [100] with a composition of {Cu(H₂O)[OOC(CH₂)PO₃]}_n^n–. Hydrated Cu(2) cations are accommodated between the chains as counterions. 1 and 2 show structural features of cation exchangers. Magnetic measurements reveal a paramagnetic Curie‐Weiss behavior. Compound 2 shows antiferromagnetic coupling between Cu²⁺ ions due to a super‐superexchange coupling. The UV/Vis spectra of 1 suggest three d–d transition bands at 763 nm (²B₁ → ²E), 878 nm (²B₁ → ²B₂), and 1061 nm (²B₁ → ²A₁). Thermoanalytical investigations in air show that compound 1 is stable up to 165 °C, whereas decomposition of 2 begins at 63 °C.     

Crystal Structure,Spectroscopic and Thermal Behaviour of Bis(saccharinato)tetrakis(pyridine)nickel(II) Dipyridine

The crystal structure of [Ni(sac)₂py₄] · 2 py (sac = saccharinate anion; py = pyridine) has been solved by single crystal X-ray diffractometry. lt crystallises in the orthorhombic space group Pcan with Z = 4. Coordination of the saccharinate anion to the metal centre occurs, in a rather unusual way, through the carbonylic oxygen atom. The IR and Raman spectra of the complex have been analyzed in detail and assigned on the basis of the structural data. The thermal behaviour was investigated by means of TG and DTA methods.     

Synthesis,Crystal Structure and Spectroscopic Properties of Bis(1‐(E)‐2‐formylpyridine semicarbazone)nickel(II) Diperchlorate Monohydrate

Pale‐green crystals of the title complex were prepared by reaction of 2‐formylpyridine semicarbazone (HCSpy) and nickel(II) perchlorate in boiling ethanol. The crystals are triclinic with the nickel ion in an octahedral arrangement, coordinated by two nitrogen atoms and one oxygen donor atom from each ligand molecule. The effect of coordination on bond lengths and angles was explored by comparison with the single‐crystal structure data of the free ligand HSCpy, which was collected as well. The assumed coordination mode was supported by ¹H and ¹³C NMR spectroscopic data. A detailed analysis of the electronic properties, including semi‐empirical quantummechanical calculations is presented. Furthermore, the data obtained from magnetic susceptibility and EPR measurements are in accordance with a low‐spin d⁸ nickel(II) complex.     

A New Complex of Europium(II) with edta – Structure and Spectroscopy

A new complex of europium(II) with ethylenediaminetetraacetic acid was obtained by electrochemical reduction. The compound is composed of polymeric chains, guanidinium cations and water molecules. The Eu²⁺ cation is eight‐coordinate (two nitrogen atoms and six carboxylate oxygen atoms), and contrary to europium(III) complexes with edta, does not contain water molecules in the first coordination sphere. Relationships between the coordination mode and IR as well as UV–Vis spectra are discussed.     

Synthesis and spectroscopic and electrochemical studies of novel benzo- or 2,3-naphtho-fused tetraazachlorins, bacteriochlorins, and isobacteriochlorins

Benzene- or 2,3-naphthalene-ring-expanded tetraazachlorins (TACs), tetraazabacteriochlorins (TABCs), and tetraazaisobacteriochlorins (TAiBCs) have been synthesized by using tetramethylsuccinonitrile as a source of hydrogenated sites. The derived compounds were characterized by using NMR spectroscopy, X-ray crystallography, electronic and magnetic circular dichroism (MCD) spectroscopy, and electrochemical and spectroelectrochemical methods. X-ray analysis revealed that the benzene-fused TAiBC deviates slightly from planarity at the hydrogenated sites as a result of the presence of sp(3) carbons, which prefer a nonplanar tetrahedral conformation. The spectral data were analyzed by using a band deconvolution technique. In the electronic absorption spectra of TAC and TABC species, the Q band splits into two intense components and smaller splittings were observed for the 2,3-naphthalene-fused derivatives relative to the benzo-fused species. In contrast, in the case of TAiBCs, the Q band splitting was apparently not observed in absorption spectra, as expected from the C(2v) molecular symmetry. However, MCD signals of the Q band in TAiBCs showed Faraday B terms, implying that the accidental degeneracy of the LUMO and LUMO+1 was broken even for adjacently ring-fused species. Relative molecular orbital energies were estimated by using cyclic and differential pulse voltammetry. The first reduction potentials were close for TACs and TABCs, although those of TAiBCs shifted to more negative potentials. In contrast, although TABCs and TAiBCs exhibited similar first oxidation potentials, those of TACs appeared at more positive potentials. These properties were reproduced and rationalized by molecular orbital and configuration interaction calculations within the framework of the ZINDO/S Hamiltonian. DFT-level frequency calculations have succeeded in reproducing the IR spectra for low-symmetry tetraazaporphyrin (TAP) derivatives for the first time. The relationship between structures and spectral features is discussed.     

Synthesis,Crystal Structure and Spectroscopic Properties of [2,13‐Bis(1‐naphthalenylmethyl)‐5,16‐dimethyl‐2,6,13,17‐tetraazatricyclo(14,4,01.18,07.12)docosane]copper(II) Diperchlorate Acetonitrile Disolvate

The N‐functionalized macrocyclic ligand 2,13‐bis(1‐naphthalenylmethyl)‐5,16‐dimethyl‐2,6,13,17‐tetraazatricyclo(14,4,0^1.18,0^7.12)docosane (L³) and its copper(II) complex were prepared. The crystal structure of [Cu(L³)](ClO₄)₂·2CH₃CN was determined by single‐crystal X‐ray diffraction at 150 K. The copper atom, which lies on an inversion centre, has a square planar arrangement and the complex adopts a stable trans‐III configuration. The longer distance [2.081(2) Å] for Cu–N(tertiary) compared to 2.030(3) Å for Cu–N(secondary) may be due to the steric effect of the attached naphthalenylmethyl group on the tertiary nitrogen atom. Two perchlorate ions are weakly attached to copper in axial sites and are further connected to the ligand of the cation through NH ··· O hydrogen bonds [N ··· O 3.098 Å]. IR and UV/Vis spectroscopic properties are also described.     

Synthesis,Electrochemistry, and Spectroscopy of Blue Platinum(II) Polyynes and Diynes

The smallest band gap observed so far (1.77 eV) for an organometallic polymer is exhibited by the blue, rigid-rod polymer 2 , which is prepared by the reaction of trans-[PtCl₂(PnBu₃)₂] with one equivalent of 1 .     

Neue Cyclosilicate der Alkalimetalle: Cs5AgSi3O9 und Cs6Na6Si6O18

New Alkali Cyclosilicates: Cs₅AgSi₃O₉ and Cs₆Na₆Si₆O₁₈ The new cyclosilicates were obtained from reactions of the binary oxides at 450–500 °C under inert gas atmosphere. Cs₅AgSi₃O₉ crystallizes in the space group P2₁/m with the lattice constants a = 968,2(2) pm, b = 652,7(1) pm, c = 1162,6(3) pm, β = 93,84(2)° and Cs₆Na₆Si₆O₁₈ in R‐3m with a = 1208,0(1) pm, c = 1458,9(2) pm (IPDS data sets). The characteristic features are isolated rings, [Si₃O₉]^6– and [Si₆O₁₈]^12–, respectively. In Cs₅AgSi₃O₉ these are connected via Ag⁺ to chains. Layers of [NaO₄]‐tetrahedra separate the hexameric rings in Cs₆Na₆Si₆O₁₈. Coordination numbers of caesium are observed between C.N. 3 and C.N. 9 in these alkali rich cyclosilicates. MAPLE calculations of both cyclosilicates as well as the absorption and IR spectrum of Cs₅AgSi₃O₉ are presented. Preparative and thermoanalytical techniques have been used to investigate the reactivity of Cs₅AgSi₃O₉ in the presence of cobalt and nickel metal.     

Synthesis,Characterization, X‐ray Structures,and Solution Studies of Nickel(II) Complexes of an Aza‐Crown Macrocycle with a Hydroxyl Pendant‐Armed

The 18‐membered mixed‐donor macrocycle 6,7,8,9,10,11,12,13,20,21‐decahydro‐5H, 19H‐dibenzo[b,m][1,15,5,8,11]dioxatriazacyclooctadecin‐20‐ol ( L ), which contains N₃O₃ donor set, was synthesized. Also two nickel(II) complexes of L have been synthesized and characterized by X‐ray crystallography, FT‐IR, UV‐Vis absorption spectroscopy and elemental analysis. The structure of complexes shows an unexpected anion dependence. Reaction of Ni(ClO₄)₂·6H₂O with L afforded [Ni L ](ClO₄)₂·CH₂Cl₂ complex in which L uses all donor atoms and acts as a hexadentate ligand so forming a mononuclear nickel(II) complex in distorted octahedral geometry. Contrasting with this, when NiCl₂·6H₂0 is used, the product complex [{Ni L Cl}₂(μ‐Cl)₂] is dimeric and consists of two Ni L Cl units bridged by two chloride ions. The coordination geometry of each nickel atom is a distorted octahedral. In this complex L is exo‐coordinated via only three nitrogen atoms to a nickel ion, which is bound to two cis bridging chloride and one non‐bridging chloride too. Also complexing properties of L towards Ni(ClO₄)₂·6H₂O and NiCl₂·6H₂0 have been determined by UV‐Vis titration in methanol. The computer treatment of the data confirmed the 1:1 metal to ligand stoichiometry for two complexes in solution and gave reliable values for corresponding stability constants (logK = 3.00 ± 0.02 with Ni(ClO₄)₂·6H₂O and logK = 3.29 ± 0.06 with NiCl₂·6H₂0).     

Crystal Structure and IR Spectrum of Diaqua(o‐phenanthroline) bis(saccharinato)lead(II)

The crystal structure of [Pb(sac)₂ophen(H₂O)₂] (sac = saccharinate anion; ophen = 1,10‐phenanthroline) has been solved by single X‐ray diffractometry. It crystallizes in the monoclinic space group C2/c with Z = 4. The Pb^II atom presents the coordination number eight with unusual coordination of the ligand atoms between square‐antiprism and dodecahedron. The saccharinate anion acts as a bidentate ligand. The i. r. spectrum of the complex has been analyzed in detail and assigned on the basis of the structural peculiarities.     

Crystal Structure and Characterization of Two Layered Copper(II) Coordination Polymers with Anions of 3‐Phosphonopropionic Acid and (RS)‐2‐Phosphonobutyric Acid

Blue single crystals of Cu[μ₃‐O₃P(CH₂)₂COOH] · 2H₂O ( 1 ) and Cu[(RS)‐μ₃‐O₃PCH(C₂H₅)COOH] · 3H₂O ( 2 ) were prepared in aqueous solutions (pH = 2.5–3.5). 1 crystallizes in space group Pbca (no. 61) with a = 812.5(2), b = 919.00(9), and c = 2102.3(2) pm. Cu²⁺ is fivefold coordinated by three oxygen atoms stemming from [O₃P(CH₂)₂COOH]^2– anions and two water molecules. The Cu–O bond lengths range from 194.0(3) to 231.8(4) pm. The connection between the [O₃P(CH₂)₂COOH]^2– anions and the Cu²⁺ cations yields a polymeric structure with layers parallel to (001). The layers are linked by hydrogen bonds. 2 crystallizes in space group Pbca (no. 61) with a = 1007.17(14), b = 961.2(3), c = 2180.9(4) pm. The copper cations are surrounded by five oxygen atoms in a square pyramidal fashion with Cu–O bonds between 193.6(4) and 236.9(4) pm. The coordination between [O₃PCH(C₂H₅)COOH]^2– and Cu²⁺ results in infinite puckered layers parallel to (001). The layers are not connected by any hydrogen bonds. Each layer contains both R and S isomers of the [O₃PCH(C₂H₅)COOH]^2– dianion. Water molecules not bound to Cu²⁺ are intercalated between the layers. UV/Vis spectra suggest three d–d transition bands at 743, 892, 1016 nm for 1 and four bands at 741, 838, 957, and 1151 nm for 2 , respectively. Magnetic measurements suggest a weak antiferromagnetic coupling between Cu²⁺ due to a super‐superexchange interaction. Thermoanalytical investigations in air show that the compounds are stable up to 95 °C ( 1 ) and 65 °C ( 2 ), respectively.     

Synthesis, spectroscopy, and electrochemistry of tetra-tert-butylated tetraazaporphyrins, phthalocyanines, naphthalocyanines, and anthracocyanines, together with molecular orbital calculations

Tetraazaporphyrins (TAPs), phthalocyanines (Pcs), naphthalocyanines (Ncs), and anthracocyanines (Acs) with four tert-butyl groups attached at similar positions have been synthesized, and their electronic absorption, magnetic circular dichroism (MCD), IR, and voltammetric properties were studied and interpreted with the help of quantum-mechanical calculations. Through the preparation of a series of compounds with the same number of the same substituent, the effects of the increase in the size of the ring system were clearly derived. The main results may be summarized as follows. 1) The Q band shifts to longer wavelength and its intensity increases, but with decreasing degree of change with increasing molecular size. If the size of the effect of benzene directly fused to the TAP skeleton is set at unity, the effects of the second and third benzene units are roughly 0.8 and 0.5, respectively. 2) The splitting of the Q bands in metal-free compounds decreases with increasing molecular size, so that the Q bands of H2Nc and H2Ac appear as single bands. 3) The magnitude of the orbital angular momentum of the excited state of the ligand decreases with increasing molecular size. 4) Interestingly, the ring current, as judged from the positions of pyrrole proton signals in the 1H NMR spectrum, appears to decrease with increasing molecular size. 5) The first reduction potential becomes less negative, but only slightly, whereas the first oxidation potential shows a marked shift to less positive values with increasing molecular size, indicating that the HOMO destabilizes significantly as the molecule becomes larger. 6) In 5), the extent of the HOMO destabilization with molecular size differs depending on the central metal, so metals producing smaller destabilization effects can allow larger macrocycles. Of the metals studied, the most effective is cobalt, and the practical size limit is represented by the Acs. 7) The IR spectra become simpler the larger the molecule, and the main bands were assigned by DFT calculations. 8) The trend in experimentally determined redox potentials and electronic absorption and MCD spectra were reasonably reproduced by MO calculations using the ZINDO/S Hamiltonian. 9) EPR data for several metallocomplexes are also reported.     

Synthesis,Crystal Structure,and Reactivity of Na5[CuO2](OH)2

Na₅[CuO₂](OH)₂ has been obtained as orange single crystals from mixtures of NaOH, Na₂O and Cu₂O in sealed Ag containers. The crystal structure has been refined from X‐ray diffraction data (IPDS data, Pnma, Z = 4, a = 607.4(1) pm, b = 891.2(1) pm, c = 1201.0(2) pm, R₁ = 0.03). The characteristic unit is the bent [CuO₂]^3– complex (∠(O–Cu–O) = 170°). The reactivity of Na₅[CuO₂](OH)₂ has been studied by DSC and in situ X‐ray diffraction techniques. IR spectroscopy has been used for further characterization. The Madelung Part of the Lattice Energy (MAPLE) has been calculated as well.     

Syntheses,Structures, and Properties of Mono‐ and Tetranuclear Nickel(II) Complexes Derived from a Tridentate Schiff Base Ligand

Three new nickel(II) complexes constructed with N‐(2‐hydroxybenzyl)‐β‐alanine (H₂L), namely [NiL(phen)H₂O]·H₂O ( 1 ) (phen = 1.10‐phenanthroline), [Ni₄L₄(H₂O)₄]·5H₂O ( 2 ) and K[Ni₄L₄(NCS)(H₂O)₅]·5.42H₂O ( 3 ) have been synthesized and characterized by single‐crystal X‐ray diffraction analysis. Complex 1 exhibits a discrete structure, and the structures are bound together through hydrogen bonding to a one‐dimensional chain in ladder‐like fashion. Complexes 2 and 3 contain similar [Ni₄(μ₂‐O)₆] cores with “zig‐zig” arrangement. In complex 3 , the tetranuclear nickel units [Ni₄L₄(H₂O)₄] and [Ni₄L₄(NCS)(H₂O)] are alternately bridged by potassium atoms to a one‐dimensional chain. The neighboring chains are further linked up by {K₂O₂} units to a two‐dimensional layer structure. Moreover, the IR, XRD, TGA and the temperature‐dependent magnetic susceptibility for 2 and 3 have also been studied.     

Synthesis and Spectroscopic Characterization of New Lead(II) Thiosaccharinates. Molecular Structure of Bis(thiosaccharinato)tetrakis(pyridine)dilead(II) and Thiosaccharinato‐bis(1,10‐phenantroline)lead(II) Thiosaccharinate

Four new lead(II) thiosaccharinate complexes: [Pb(tsac)₂H₂O] (1) (tsac: thiosaccharinate anion), [Pb₂(tsac)₄(py)₄] (2) (py: pyridine), [Pb(tsac)(o‐phen)₂](tsac)·CH₃CN (3) (o‐phen: 1,10‐phenantroline), and [Pb(tsac)₂(bipy)] (4) (bipy: 2,2′‐bipyridine) were prepared. The infrared and electronic spectra as well as the thermal analysis of all the compounds were recorded and discussed. The thiosaccharinate anion acts in three different coordination forms, one of then reported for the first time. The crystal structures of complexes 2 and 3 have been determined by single crystal X‐ray diffractometry. In complex 2 , two monomeric moieties are joined together forming a symmetric bis‐μ‐sulphur bridged dimer by interaction of two lead(II) atoms through the exocyclic sulphur atoms of two thiosaccharinate ligands. The seven‐fold coordination sphere of each lead atom is completed by two pyridine nitrogen atoms and by another sulfur and two nitrogen atoms of the thiosaccharinate anions. In complex 3 , the lead(II) atom is coordinated by four nitrogen atoms of two 1,10‐phenantroline molecules and by the sulfur and nitrogen atoms of one thiosaccharinate ion. The second anion has an electrostatic interaction with the nucleus.