Renium(V) complexation with <Emphasis Type="Italic">N</Emphasis>-ethylthiourea

The stepwise complexation of rhenium(V) with N-ethylthiourea has been studied by the potentiometric method in 6 mol/L HCI at 298 K. It has been found that rhenium(V) forms five complex species with this ligand of the following compositions: [ReOLCl₄]^?, [ReOL₂Cl₃], [ReOL₃Cl₂]⁺, [ReOL₄Cl]²⁺, and [ReOL₅]³⁺. The calculated logarithms of stepwise formation constants of the complexes are the following: logK₁ = 4.10 ± 0.05, logK₂ = 3.16 ± 0.02, logK₃ = 2.61 ± 0.02, logK₄ = 2.26 ± 0.02, and logK₅ = 1.80 ± 0.02. It has been shown that the introduction of the ethyl radical into the thiourea molecule leads to an increase in the stability of rhenium(V) complexes.     

Crystal structures of <Emphasis Type="Italic">trans</Emphasis>-dichlorobis(ethylendiamine) rhodium(III) with univalent anions

The crystal structures of the compounds trans-[Rh(en)₂Cl₂]Cl₂ · H₅O₂ (I), trans-[Rh(en)₂Cl₂]ClO₄ (II), and trans-[Rh(en)₂Cl₂]ReO₄ (III) are determined. The crystal data are: I, a = 10.860(3) Å, b = 7.795(2) Å, c = 9.023(3) Å; β = 111.56(10)°, P2₁/c space group, Z = 4, d _x = 1.875 g/cm³; II, a = 6.593(2) Å, b = 8.309(3) Å, c = 11.922(4) Å, α = 83.55(10)°, β = 79.80(10)°, γ = 75.38(10)°, P \(\bar 1\) space group, Z = 2, d _x = 2.106 g/cm³; III, a = 6.533(2) Å, b = 16.391(4) Å, c = 12.411(3) Å; β = 98.30(10)°, P2₁/c space group, Z = 4, d _x = 2.749 g/cm³. The compounds are examined by IR spectroscopy and powder XRD. The solubility of the isolated crystalline phases in water decreases in the following order: trans-[Rh(en)₂Cl₂]Cl₂·H₅O₂ > trans-[Rh(en)₂Cl₂]ClO₄ > trans-[Rh(en)₂Cl₂]ReO₄.     

Effective reduction of <Emphasis Type="Italic">p</Emphasis>-nitrophenol catalyzed by nickel(II) adamantane complexes

Two Ni(II) adamantane complexes, [Ni(bqad)Cl₂] (1) and [Ni(bpad)(dmbp)(H₂O)](ClO₄)₂·CH₃OH H₂O (2) (bqad = N,N′-bis(2-quinolinylmethyl) amantadine, bpad = N,N′-bis(2-pyridylmethyl)amantadine, dmbp = 5,5′-dimethyl-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, infrared spectroscopy and single crystal X-ray diffraction. The nickel centers in complex 1 have a distorted tetragonal pyramidal geometry, while the coordination polyhedron of 2 can be described as a distorted octahedron. The reaction kinetics for reduction of p-nitrophenol to p-aminophenol catalyzed by these complexes has been investigated by UV–visible spectrophotometry. Complex 1 exhibits a higher turnover frequency of 1.4 min^?1 for the reduction of p-nitrophenol.     

Binuclear copper(II) complexes with acyldihydrazones of <Emphasis Type="Italic">N</Emphasis>-benzenesulfonyl-<Emphasis Type="Italic">L</Emphasis>-aspartic acid

The structure and the EPR spectra of copper(II) coordination compounds with acyldihydrazones of N-benzenesulfonyl-L-aspartic acid and salicylaldehyde (2-hydroxyacetophenone) were described. The compounds were studied by chemical and thermal analyses, IR spectroscopy, and EPR. The molecular and crystal structures of copper(II) complexes with N-benzenesulfonyl-L-aspartic acid bis(salicylidene)hydrazone (H₄L¹) [Cu₂L¹ · 2Py] · 1.5 H₂O was determined by X-ray diffraction. The crystals are triclinic: a = 10.4714(4) Å, b = 12.9702(5) Å, c = 14.6187(9) Å, α = 104.763(2)°, β = 93.082(2)°, γ = 111.4240(10)°, space group P \(\bar 1\), Z = 2. The binuclear complexes containing copper cations whose coordination polyhedra are connected by an aliphatic spacer (Cu...Cu, 8.669 Å) are additionally linked by phenoxy bridges (Cu...Cu, 3.398 Å). The EPR spectra of these compounds in solutions exhibit an isotropic signal of seven HFS lines due to two equivalent copper ions with the spin Hamiltonian parameters g = 2.115?2.120, a _Cu = (35.5?38.0) × 10^?4 cm^?1, which is indicative of weak exchange interactions between the paramagnetic sites.     

Synthesis and structure of bis(1,2-diaminoethane) copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-hydroxybenzoate) monohydrate and <Emphasis Type="Italic">trans</Emphasis>-diaquabis(1,2-diaminoethane)copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-aminobenzoate)

X-ray structural analysis has been performed for two complex compounds: Cu(en)₂(o-HB)₂H₂O (I) (a = 16.873(4) Å, b = 8.713(2) Å, c = 14.803(3) Å, β = 91.15(2)°, V = 2175.8(8) ų, C2/c, Z = 4, R(F) = 0.0263, 1516 reflections with I > 3σ (I)) and [Cu(en)₂(OH₂)₂]²⁺(o-AB^?)₂ (II) (a = 7.488(5) Å, b = 22.122(8) Å, c = 7.856(5) Å, β = 118.77(2)°, V = 1140.7(11) ų, P2₁/n, Z = 2, R(F) = 0.0432, 1684 reflections with I > 3σ(I)) synthesized under identical conditions (en is ethylenediamine, o-HB is o-hydroxybenzoate, and o-AB is o-aminobenzoate). Although the compounds were assumed to have similar structures and the Cu-Lig bond lengths and the cis and trans angles are acceptable for an octahedral structure, the geometric parameters of o-HB suggest that the copper atom has a plane square environment.     

The role of substituents in a bidentate <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-chelating ligand on the substitution of aqua ligands from mononuclear Pt(II) complexes

The rate of substitution of aqua ligands from three mononuclear platinum(II) complexes, namely [Pt{2-(pyrazol-1-ylmethyl)pyridine}(H₂O)₂](ClO₄)₂, [Pt(H ₂ Py)]; [Pt{2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine}(H₂O)₂](ClO₄)₂, [Pt(dCH ₃ Py)] and [Pt{2-[(3,5-bis(trifluoromethyl)pyrazoly-1-ylmethyl]pyridine}(H₂O)₂](ClO₄)₂, [Pt(dCF ₃ Py)] by thiourea, N,N-dimethylthiourea and N,N,N′,N′-tetramethylthiourea, was studied in aqueous perchloric acid medium of constant ionic strength. The substitution reactions were investigated under pseudo-first-order conditions as a function of nucleophile concentration and temperature using UV/Visible and stopped-flow spectrophotometries. The observed pseudo-first-order rate constants, \( k_{{{\text{obs }}\left( {1/2} \right)}} \), for the stepwise substitution of the first and second aqua ligands obeyed the rate law: \( k_{{{\text{obs}}\left( {1/2} \right)}} = k_{{2 \left( { 1 {\text{st/2nd}}} \right)}} \left[ {\text{Nu}} \right] \). The first substitution reaction takes place trans to the pyrazole ligand, while the second entering nucleophile is stabilised at the reaction site trans to the pyridine ligand. The rate of substitution of the first aqua ligand from the complexes followed the order: Pt(dCF ₃ Py) > Pt(H ₂ Py) > Pt(dCH ₃ Py), while that of the second was Pt(H ₂ Py) ≈ Pt(dCF ₃ Py) > Pt(dCH ₃ Py). Lower pK _a values were found for the deprotonation of the aqua ligand cis to the pyrazole ring. Density functional theory calculations were performed to support the interpretation of the experimental results.     

Synthesis,crystal structure,and thermodynamics of a high-nitrogen copper complex with <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-bis-(1(2)H-tetrazol-5-yl) amine

A new high-nitrogen complex [Cu(Hbta)₂]·4H₂O (H₂bta = N,N-bis-(1(2)H-tetrazol-5-yl) amine) was synthesized and characterized by elemental analysis, single crystal X-ray diffraction and thermogravimetric analyses. X-ray structural analyses revealed that the crystal was monoclinic, space group P2(1)/c with lattice parameters a = 14.695(3) Å, b = 6.975(2) Å, c = 18.807(3) Å, β = 126.603(1)°, Z = 4, D _c = 1.888 g cm^?3, and F(000) = 892. The complex exhibits a 3D supermolecular structure which is built up from 1D zigzag chains. The enthalpy change of the reaction of formation for the complex was determined by an RD496–III microcalorimeter at 25 °C with the value of ?47.905 ± 0.021 kJ mol^?1. In addition, the thermodynamics of the reaction of formation of the complex was investigated and the fundamental parameters k, E, n, \( \Updelta S_{ \ne }^{{{\uptheta}}} \), \( \Updelta H_{ \ne }^{{{\uptheta}}} \), and \( \Updelta G_{ \ne }^{{{\uptheta}}} \) were obtained. The effects of the complex on the thermal decomposition behaviors of the main component of solid propellant (HMX and RDX) indicated that the complex possessed good performance for HMX and RDX.     

Solution Thermodynamics of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis><Superscript>/</Superscript>-Ethylenebis-(salicylideneiminato)-diaquochromium(III) Chloride in Aqueous Dimethylsulphoxide

The densities, viscosities and refractive indices of N,N ^/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, [Cr(salen)(H₂O)₂]Cl, in aqueous dimethylsulfoxide (DMSO) with different mass fractions (w ₂ = 0.20, 0.40, 0.60, 0.80 and 1.00) of DMSO were determined at 298.15, 308.15 and 318.15 K under atmospheric pressure. From measured densities, viscosities and refractive indices the apparent molar volumes (V _φ ), standard partial molar volume (V _φ ⁰ ), the slope (S _V ^* ), standard isobaric partial molar expansibility (φ _E ⁰ ) and its temperature dependence (?φ _E ⁰ /?T) _p , the viscosity B-coefficient, its temperature dependence (?B/?T), solvation number (S _n ) and apparent molar refractivity (R _D ^φ ), etc., were calculated and discussed on the basis of ion–ion and ion–solvent interactions. These results revealed that the solutions are characterized by ion–solvent interactions rather than by ion–ion interactions and the complex behaves as a long range structure maker. Thermodynamics of viscous flow was discussed in terms of transition state theory.     

Mononuclear cobalt (III) complexes with <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-bromobenzylamine and <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-chlorobenzylamine

Cobalt (III) complexes with N-salicylidene-2-hydroxy-5-bromobenzylamine (H₂sbba) and N-salicylidene-2-hydroxy-5-chlorobenzylamine (H₂scba), [n-(C₄H₉)₄N][Co(sbba)₂] (I) and [n-(C₄H₉)₄N][Co(scba)₂] (II), were synthesized. The crystal structure of II was determined by the single-crystal X-ray diffraction method at 90 K confirming its crystallization in the monoclinic space group P2₁/n with a = 11.729(2) Å, b = 16.901(3) Å, c = 21.483(4) Å, β = 98.840(4)°, V = 4208.2(14) ų, D_x = 1.295 g cm^?3, and Z = 4. The R1 [I > 2σ(I)] and wR2 (all data) values of 0.0664 and 0.1920, respectively, for all 9521 independent reflections. The compound is composed of a tetra(n-butyl)ammonium cation and an octahedral cobalt(III) complex anion with two scba^2? ligands in a meridional fashion. The electronic spectral features of I and II are consistent with the octahedral cobalt(III) ion with an N₂O₄ donor set.     

Synthesis and structure of Pt(II) acetamidate complexes containing <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-substituted ethylenediamine and trimethylenediamine

Reactions of acetamide with platinum(II) diamines [Pt(N,N-DimeEn)Cl₂], [Pt(Tm)Cl₂], and [Pt(N,N-DimeTm)Cl₂] (N,N-DimeEn = (CH₃)₂N(CH₂)₂NH₂, Tm = NH₂(CH₂)₃NH₂, N,N-DimeTm = (CH₃)₂N(CH₂)₃NH₂) with preliminary precipitation of chlorine ions by silver salts gave binuclear Pt(II) acetamidates [Pt₂(CH₃)₂N(CH₂)₂NH₂)₂(μ-NHCOCH₃)₂](NO₃)₂ · H₂O (I), [Pt₂(NH₂(CH₂)₃NH₂)₂)(μ-NHCOCH₃)₂](NO₃)₂ · H₂O (II), and [Pt₂(CH₃)₂N(CH₂)₃NH₂)₂(μ-NHCOCH₃)₂](HSO₄)₂ (III), whose crystal structures were determined. Crystals of I are monoclinic: a = 14.459(2) Å, b = 17.197(3) Å, c = 9.822(2) Å, β = 105.923(10)°, V = 3348.6(8) ų, space group P2(1)/c, Z = 4, R _hkl = 0.0419 for 6663 reflections. Complex I is a binuclear acetamidate with bridging (NHCOCH₃)^? ligands, one of which is bound to two Pt atoms through the N and O atoms, and the other ligand is bound only through the N atom. The Pt-Pt distance is 2.987(1) Å. Crystals of II are monoclinic: a = 10.213(7) Å, b = 13.373(9) Å, c = 16.533(11) Å, β = 97.971(9)°, V = 2236(3) ų, space group P2(1)/n, Z = 4, R _hkl = 0.557 for 6462 reflections. The Pt-Pt distance is 3.057(1) Å. Crystals of III are monoclinic: a = 10.557(12) Å, b = 18.531(2) Å, c = 14.4744(17) Å, β = 108.705(2)°, V = 2682(5) ų, space group P2(1)/n, Z = 4, R _hkl = 0.569 for 8506 reflections. The Pt-Pt distance is 3.202(1) Å. Complexes II and III are binuclear acetamidates, in which two chelating Pt(Tm) or Pt(N,N-DimeTm) moieties are coordinated through the N and O atoms of (NHCOCH₃)^? cis-bridges.     

Unusual Polymers Containing Alternating <Emphasis Type="Italic">s</Emphasis> and <Emphasis Type="Italic">d</Emphasis> Elements Connected by Bridging Pivalate

From tetrahydrofurane solutions containing Cu(II) or Co(II) and potassium pivalate (KPiv) (molar ratios Cu/K=1/10, Co/K=1/5) one can isolate polynuclear [K₃Co₂Piv₇(THF)₃] (1) and [K₆Cu₂Piv₁₀(HPiv)(THF)(H₂O)₂]\(\cdot\)2THF (2), respectively. In the solid state the structures of the compounds consist of alternating, oppositely winding helices with a step of 46.085 Å for 1 and 25.260 Å for 2. In 2, the bridging pivalates link the infinite helices into layers. For both compounds, an important peculiarity of the structure is wide separation of transition metal ions (at least 5.327 Å for 1 and 6.791 Å for 2). Due to the presence of excess KPiv in the reaction system, the Cu(II) and Co(II) ions do not “coalesce” into polynuclear complexes typically observed in transition metal pivalates; instead they form unusual polymer systems containing alternating atoms of s and d elements. For transition metal pivalates, this type of structure was found for the first time.     

Synthesis and X-ray study of 6<Emphasis Type="Italic">H</Emphasis>-chromeno[3,4-<Emphasis Type="Italic">e</Emphasis>][1,3,4]triazolo[2,3-<Emphasis Type="Italic">a</Emphasis>]pyrimidine

2-Dimethylamino methylenechromanone 1 reacted with 4H-1,2,4-triazol-3-amine in acetic acid to give only one isolated product which was identified by X-ray study as 6H-chromeno[3,4-e][1,3,4]triazolo[2,3-a]-pyrimidine. The molecular structure of 3, C₁₂H₈N₄O, was determined to be monoclinic, P2₁/c, a = 16.3875(5), b = 8.8378(3), c = 13.8392(5) Å, β = 101.190(1)°, V = 1966.22(11) ų, Z = 8.     

Crystal structure and antitumor activities of a dinuclear cobalt(II) complex based on <Emphasis Type="Italic">meso</Emphasis>-1,2,3,4-tetra(1H-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazol-2-yl)butane

The [Co₂(tbb)Cl₄]?4DMF complex, where tbb is meso-1,2,3,4-tetra(1H-benzo[d]imidazol-2-yl)butane, is synthesized and characterized by single crystal X-ray diffraction. For the complex: C₄₄H₅₄Co₂C_l4N₁₂O₄, M_r = 1074.65, monoclinic crystal system, space group P21/n, a = 9.2350(13) Å, b = 11.3566(15) Å, c = 23.879(3) Å, β = 90.547(2)°, V = 2504.3(6) ų, Z = 2, D_c = 1.425 g/cm³, λ = 0.71073 Å, μ(MoK_α) = = 0.929 mm^–1, F(000) = 1112, S = 1.047, R = 0.0765, and wR = 0.2110 for 13668 observed reflections with I > 2σ(I). It is a neutral dinuclear complex. One meso-1,2,3,4-tetra(1H-benzo[d]imidazol-2-yl)butane coordinates two cobalt(II) ions. Each cobalt(II) ion is formed by two tbb nitrogen atoms and two chloride ions. The antiproliferative activities of the complex are screened by MTT assay against Eca109 cancer cells. The complex exhibits inhibition on the growth of Eca109 cancer cells with IC₅₀ of 22.1±6.7 μM after 48 h treatment. The cobalt complex has potential application in treatment of Eca109 cancer. CCDC 1015791.     

Crystal structure of oxonium <Emphasis Type="Italic">trans</Emphasis>(O)-<Emphasis Type="Italic">cis</Emphasis>-(C)-dicyanobis(2-picolinato)cobaltate(III) hydrate: Two types of proton site

The trans(O)-cis(C)-bis(pyridine-2-carboxylato)dicyanocobaltate(III) ions, [Co(Pic)₂(CN)₂]^?, crystallize from acid medium with three water molecules per two crystallographically nonequivalent complexes whose charge is compensated by protons. One of the water molecules forms an oxonium ion (H₃O⁺) with a proton. The other two water molecules bound to each other through a short hydrogen bond O-H…O (2.403(2) Å) and thus forming (H₅O₂)⁺ cations is another proton site. The (H₃O)(H₅O₂)[Co(Pic)₂(CN)₂]₂ crystals are monoclinic: a = 10.7027(7) Å, b = 25.786(1) Å, c = 11.4865(8) Å, β = 91.411(9)°, Z = 4, space group P2₁/n.     

Crystallographic and conformational analysis of (<Emphasis Type="Italic">E</Emphasis>)-2-isopropyl-4-(<Emphasis Type="Italic">p</Emphasis>-tolyldiazenyl)phenol

The molecular and crystal structures of the title compound, C₁₆H₁₈N₂O, were characterized and determined by single crystal X-ray diffraction method in addition to spectroscopic means such as IR, UV–VIS and ¹H NMR. The compound crystallizes in orthorhombic space group P bca, with a = 9.3350(5) Å, b = 23.4878(13) Å, c = 26.5871(12) Å, Z = 16, D _calc. = 1.1591(1) g/cm³, μ (MoK_α) = 0.073 mm^?1. Monomers of the compound in the crystal structure are linked into C(7) and C(8) chains generated by translation along the [1 0 0] direction with the aid of O–H···N type H-bonds which serve to the stabilization of periodic organization of the molecules beside major and minor component in the disordered azo fragment. In order to describe conformational flexibility and the crystal packing effects on the molecular conformation, potential barriers regarding the rotation along both Ar–N bonds were calculated by varying the related torsional degrees of freedom in every 10° ranging from ?180° to +180° via quantum chemical calculations at DFT/B3LYP level.     

Structural studies of nickel(II) complexes with 1-<Emphasis Type="Italic">tert</Emphasis>-butylimidazole-2-thione and 3-phenyl-5-methyl-pyrazole ligands

The nickel(II) complexes dichlorobis(1-tert-butylimidazole-2-thione)nickel(II) [Ni(tm ^t-Bu)₂Cl₂] (1), dinitratobis(1-tert-butylimidazole-2-thione)nickel(II) [Ni(tm ^t-Bu)₂(NO₃)₂] (2), dichloro-bis(3-phenyl-5-methyl-pyrazole)(1-tert-butylimidazole-2-thione)nickel(II) [Ni(pz^Ph,MeH)₂(tm ^t-Bu)Cl₂] (3) and dinitratobis(3-phenyl-5-methyl-pyrazole)(1-tert-butylimidazole-2-thione)nickel(II) [Ni(pz^Ph,MeH)₂(tm ^t-Bu)(NO₃)₂] (4) have been synthesized and studied. The single crystal X-ray diffraction analysis was carried out for 1 and 4 {Bruker Kappa Apex-II CCD diffractometer, MoK _α radiation}. Crystal data for 1: monoclinic C2/c, a = 16.949(2) Å, b = 8.6647(10) Å, c = 15.461(3) Å, β = 117.662(4)°, V = 2011.1(5) ų, Z = 4, D _calc = 1.460 g/cm³. Crystal data for 4: triclinic P-1, a = 9.9775(7) Å, b = 11.2254(8) Å, c = 14.8068(10) Å, α = 75.401(4)°, β = 87.422(4)°, γ = 74.874(4)°, V = 1548.86(19) ų, Z = 2, D _calc = 1.405 g/cm³. Coordination core of complex 1 adopts distorted tetrahedral geometry whereas core 4 has distorted octahedral geometry. The bonded nitrates are of two types coordinating as monodentate and bidentate ligands.     

Crystal Structure of <Emphasis Type="Italic">DL</Emphasis>-Valinium Tetrafluoroantimonate(III) Monohydrate

The crystal structure of an antimony(III) fluoride complex of the composition (C₅H₁₂NO₂)SbF₄·H₂O (I) involving a cation of α-amino isovaleric acid (DL-valine, Val) is determined. Crystals are monoclinic: a = 12.2024(2) Å, b = 6.1636(1) Å, c = 15.5167(3) Å, Z = 4, space group P2₁/c. The structure is formed of DL-valinium (C₅H₁₂NO₂)⁺ cations, complex [SbF₄]_n^n? anions having a polymeric chain structure, and crystallization water molecules. The [SbF₄]_n^n? complex anions consist of trigonal SbF4E bipyramids joined together by asymmetric bridging Sb–F(3)···Sb bonds. The structural units are organized into a threedimensional framework via N–H···F, N–H···O, and O–H···F hydrogen bonds.     

Cobalt(II) and nickel(II) cloride complexes with 4,5-(<Emphasis Type="Italic">n</Emphasis>-pyridylethylene)-dithio-1,3-dithiol-2-thiones (<Emphasis Type="Italic">n</Emphasis> = 2, 4)

The NiCl₂ and CoCl₂ complexes with 4,5-(2-pyridylethylene)-dithio-1,3-dithiol-2-thione (L¹) and 4,5-(4-pyridylethylene)-dithio-1,3-dithiol-2-thione (L²) were described. The L¹ ligand shows bidentate coordination through the pyridyl N atoms and the thiol S atoms in a tetrahedral [CoCl₂(L¹)] complex (I) and in an octahedral [NiCl₂(L¹)₂](MeCN)₂ complex (II). The L² ligand exhibits monodentate coordination through the pyridyl N atom in tetrahedral complexes [CoCl₂(L²)₂ (III) and [NiCl₂(L²)₂] (IV). Complexes I, III, IV in crystal state are octahedral due to extra coordination of the thione S atoms or the chloride bridges responsible for the polymeric structure. The structure of the complex II · CH₂Cl₂ was determined by X-ray diffraction analysis. The crystals are monoclinic, space group P2₁/c, a = 11.895(2) Å, b = 13.374(3) Å, c = 21.873(4) Å, β = 95.30(3)°, Z = 2. The Ni atom has quasi-tetrahedral surrounding due to two chloride ions and two L¹ ligands coordinated through the pyridyl N atoms and the thiol S atoms.     

Structure of A Coordination Polymer [Cu(En)<Subscript>2</Subscript>CrO<Subscript>4</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

The crystal structure of [Cu(En)₂CrO₄]_n (En is ethylenediamine) is determined: a = 14.7359(4) Å, b = 9.8083(3) Å, c = 14.2664(4) Å, V = 2061.98(10) ų, space group Cmce, Z = 8, d_x = 1.931 g/cm³. It is demonstrated that the studied phase is isostructural with [Сu(Еn)₂SO₄]_n. A pseudotetragonal copper atom coordination (Cu–N 2.0204 Å and 2.0244 Å, ∠N–Cu–N 84.73°) is completed to distorted octahedral by two oxygen atoms of chromate anions (Cu–O 2.433 Å and 2.380 Å).     

Structures and enhanced third-order nonlinear optical performance of four complexes investigated by thin film <Emphasis Type="Italic">Z-</Emphasis>scan technique

Four transition metal complexes have been synthesized via hydrothermal reactions, namely, [Zn(1,3-BIB)(CH₃COO)₂]₂ 1, [Cu₂(1,4-BIB)₃(CO₃)₂](1,4-BIB)·10H₂O 2, {[Mn(H₂O)₂(1,2-BIB)₂]Cl₂}_n 3, and {[Mn(1,2-BIB)(1,4-NDC)]₂}_n 4, where 1,n-BIB = 1,n-bis(imidazol-l-yl-methyl)benzene, n = 2, 3, 4 and 1,4-NDC = naphthalene-1,4-dicarboxylic acid. Complex 1 presents a discrete ring-like structure. Complex 2 shows a ladder-like chain structure, while complex 3 has a joint-like chain structure. Complex 4 features a layer structure constructed from [Mn₂(N₄O₈)] clusters. The third-order nonlinear optical (NLO) properties of these complexes in thin films have been investigated by employing the Z-scan technique. Complexes 1–3 exhibit strong third-order NLO reverse-saturable absorption, while 4 shows third-order NLO saturable absorption and a strong self-defocusing effect. The third-order NLO susceptibilities χ ⁽³⁾ of the four complexes were calculated as 2.74 × 10^?9, 12.24 × 10^?9, 42.78 × 10^?9 and 189.32 × 10^?9 esu, respectively. The electronic structures of the complexes were investigated by density functional theory, and the origins of their NLO properties are discussed.