Self-Assembly of d10 Metal Adduct Polymers Bridged by Bipyridyl-Based Ligands

Four d¹⁰ metal polymers, cluster [AgI₂(bpe)] _n (1), complexes [Zn(tmp)I₂] _n (2), [Cd(tmp)I₂] _n (3), and [Hg(tmp)Br₂] _n (4) (bpe=1,2-bis(4-pyridyl)ethane, tmp=4,4-trimethylene dipyridine) have been synthesized and structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. 1 is a cluster polymer, and exhibits a two-dimensional open structure consisting of the staircase clusters connected by regular bpe bridges. While complexes 2, 3, and 4 are one-dimensional wave-shaped coordination polymers. In contrast, 3 also displays a 2D structure with large supramolecular cavities. The diverse coordination properties of d¹⁰ metals make them good building blocks for the construction of coordination polymers with diverse architectures, which is dependent on both the rigidity and length of the bifunctional ligand and the coordination geometry of the metal ions.     

The d metal-sulfosalicylate complexes: Herring-bone, ladder and double-stranded chain frameworks with green luminescences

Assembly of 5-sulfosalicylic acid (H₃L) and d¹⁰ transition metal ions (Cd^II, Ag^I) with the neutral N-donor ligands produces five new complexes: [Cd₂(HL)₂(4,4′-bipy)₃]_n·2nH₂O (1), {[Cd₂(μ₂-HCO₂)₂(4,4′-bipy)₂(H₂O)₄][Cd(HL)₂(4,4′-bipy)(H₂O)₂]}_n (2), {[Cd(4,4′-bipy)(H₂O)₄][HL]·H₂O}_n (3), [Cd(HL)(dpp)₂(H₂O)]_n·4nH₂O (4), {[Ag(4,4′-bipy)][Hhbs]}_n (5) (4,4′-bipy=4,4′-bipyridine, dpp=1,3-di(pyridin-4-yl)propane, H₂hbs=4-hydroxybenzenesulfonic acid, the decarboxylation product of H₃L). Complex 1 adopts a 5-connected 3D bilayer topology. Complex 2 has the herring-bone and ladder chain, which are extended to a 3D network via hydrogen bonding. In 3–4 complexes, 3 is a 3D supermolecular structure formed by polymeric chains and 2D network of HL²⁻, while 4 gives the double-stranded chains. In 5, ladder arrays are stacked with the 2D networks of Hhbs⁻ anions in an –ABAB– sequence. Complexes 1–4 display green luminescences in solid state at room temperature, while emission spectra of 3 and 4 show obvious blue-shifts at low temperature.     

Syntheses,crystal structures and photophysical properties of d10 transition-metal (Ag+, Cu+, Cd2+ and Zn2+) coordination complexes based on a thiophene-containing heterocyclic thioamide

Four d¹⁰ transition-metal coordination complexes 1–4 (1: [Ag₂(TPT)₂(TPTH)₂]; 2: [Cu₆(TPT)₆]·2DMF; 3: [Cd(TPT)₂(TPTH)]·CH₃CH₂OH, 4: [Zn(TPT)₂]_n) have been constructed from a newly designed heterocyclic thioamide ligand, TPTH (TPTH = 4-(thiophen-2-yl)-pyrimidine-2-thiol). All complexes have been structurally elucidated by single crystal X-ray diffraction analyses. Except for 4, which shows a one-dimensional (1-D) chain structure, 1–3 are all discrete coordination complexes featuring dinuclear, hexanuclear and mononuclear entities, respectively. Their photophysical properties have been evaluated in the solid state at room temperature by UV–vis diffuse reflectance and luminescence spectra. Among them, 2 exhibits a strong red luminescence (λ_em = 699 nm) with a remarkable red-shift of the maximum emission compared to that of the TPTH ligand (λ_em = 536 nm). The red emission observed with 2 is ascribed to a LMCT (ligand-to-metal charge transfer) transition which agrees with the DFT calculations.     

A highly selective visual and fluorescent sensor for Pb2+ and Zn2+ and crystal structure of Cu2+ complex based-on a novel single-armed Salamo-type bisoxime

A novel single-armed Salamo-type bisoximes (H₄L) has been designed and synthesised. An obvious colour change from yellow (H₄L) to pale pink (HL-Pb²⁺) which can be visually observed by the naked eye in visible light. H₄L can act as a fluorescent sensor for ratiometric recognition of Zn²⁺ with high selectivity and sensitivity. Crystallographic data of the [Cu(HL)(μ-OAc)Cu] reveals that the two Cu²⁺ ions are both penta-coordinated with square pyramidal geometries, and forms a 2D supramolecular plane structure by hydrogen bonding interactions.     

Investigations of the local structures and spin Hamiltonian parameters for the trigonal Rh and Ir centers in rhombohedral BaTiO3

The local structures and spin Hamiltonian parameters (g factors and the hyperfine structure constants) of the Rh⁴⁺(4d⁵) and Ir⁴⁺(5d⁵) centers in rhombohedral BaTiO₃ are theoretically investigated from the formulas of these parameters for a nd⁵ (n = 4 and 5) ion with low spin (S = 1/2) in a trigonally distorted octahedron. From the calculations, the impurity ions are found not to occupy exactly the host Ti⁴⁺ site in BaTiO₃ but to suffer a slight inward shift (0.13 Å) towards the center of the oxygen octahedron along the C₃ axis, yielding much smaller trigonal distortion as compared with that of the host Ti⁴⁺ site. The theoretical spin Hamiltonian parameters based on the above impurity axial shifts are in good agreement with the observed values.     

Two new organic-inorganic hybrid compounds based on metal-pyrazine coordination polymers and Keggin polyoxometalates: effect of metal ions on thestructure

Through changing the metal ions, two Keggin polyoxometalates-based hybrid compounds, [Cu₅(pz)₆(Cl)(SiW₁₂O₄₀)] (1) and [Ag₄(pz)₃(H₂O)₂(SiW₁₂O₄₀)] (2) (pz=pyrazine), were hydrothermally synthesized and characterized by an elemental analysis, IR spectroscopy, thermogravimetric analyses, and single X-ray diffraction. In compound 1, the metal-organic motif exhibits a 6³ topological 2-D sheet, which is further fused by the [SiW₁₂O₄₀]⁴⁻ anions to construct a (6·7·8)(6³·7·8²)(6³)(6⁵·7)(6⁵·8) topological 3D structure. In compound 2, the bridging groups Ag₂(pz) connect the [SiW₁₂O₄₀]⁴⁻ anions to form a (5³)₂(5⁴·8²) topological 2-D layer, which is further linked by an [Ag(pz)]_nⁿ⁺ chains to construct a 3D structure with the (3⁴·4¹⁶·5²⁴·6¹²·7⁸·8²)(3⁴·4⁶·5⁴·6)₂(4·5²)₂ topology. It represents the highest connected network topology presently known for the polyoxometalates system. The structure differences of compounds 1 and 2 reveal that the coordination numbers and geometries of the metal ions have a great influence on the final structure and topology of the Keggin POMs-based hybrid compounds. In addition, the electrochemistry properties of the two compounds have been studied.     

Molecular and crystal structure of methyl-4-anti-hydroxyimino-1-dioxolano-13-isopropyl-10a,7-dimethylpentacyclo×[10b.8.5.04b,10b.06a,10a.01a,4a]icos-14-ene-7-carboxylate

Synthesis is performed and the molecular structure is analyzed of methyl-4-anti-hydroxyimino-1-dioxolano-13-isopropyl-10a,7-dimethylpentacyclo[10b.8.5.0^4b,10b.0^6a,10a.0^1a,4a]icos-14-ene-7-carboxylate IIa. Compound IIa C₂₇H₄₀O₄ crystallizes in monoclinic symmetry with cell parameters: a = 13.785(13) ?, b = 7.302(7) ?, c = 13.817(13) ?, β = 94.799(19)°, space group P2(1), Z = 2, d = 1.164 g/cm³. Original Russian Text Copyright ? 2009 by I. E. Smirnova, E. V. Tret’yakova, O. B. Kazakova, and Z. A. Starikova __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 393–395, March–April, 2009.     

Molecular and crystal structure of a new compound methyl-18R-13-isopropyl-10a,7-dimethyl-4-oxo-1-oxahexacyclo×[12.4.0.05a,4a.013,1201,1a.010a,6a]heneicosane-7-carboxylate

Synthesis is performed and the molecular structure is analyzed of methyl-18R-13-isopropyl-10a,7-dimethyl-4-oxo-1-oxahexacyclo[12.4.0.0^5a,4a.0^13,12.0^1,1a.0^10a,6a]heneicosane-7-carboxylate II. Compound II C₂₇H₄₀O₄ crystallizes in orthorhombic symmetry with cell parameters: a = 11.9915(15) ?, b = 12.1674(16) ?, c = 15.8094(17) ?, P2₁2₁2₁, Z = 4, d = 1.234 g/cm³. Original Russian Text Copyright ? 2009 by I. E. Smirnova, E. V. Tret’yakova, O. B. Kazakova, Z. A. Starikova, and I. V. Fedyanin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 391–392, March–April, 2009.     

Synthesis,molecular structure,and magnetic properties of bis(3,6-di-tert-butyl-o-benzosemiquinone)nickel(II) and -copper(II)

The title complexes of Ni and Cu with symmetrical 3,6-di-tert-butyl-o-benzosemiquinone are synthesized. Their EPR spectra and magnetic properties are investigated. The x-ray structure studies [Siemens R3/PC diffractometer, MoK, /20-scanning in the rang 2 2 54°, 2084 reflections withF > 4(F),R = 0.034,R _w = 0.039, monoclinic crystals,a = 9.982(2),b = 11.548(2),c = 12.145(2) Å, = 95.05(3)°,Z = 2,d _calc = 1.19 g/cm^–3, space groupP2 _l/c) demonstrated that the complex is monomeric with square-planar coordination for the Ni with theo-semiquinone ligands. The Cu complex is isostructural with the Ni (a = 9.88,b = 11.60,c = 12.15 Å, = 95°]. The dependence of the magnetic moment of the Cu complex on temperature is consistent with the presence in it of two pathways for exchange interaction. These are antiferromagnetic ligand-ligandJ ₁₂ = –179 cm^–1 and ferromagnetic metal-ligandJ ₁₃ = 100 cm^–1 (mean-square deviation 2%). The Ni complex is diamagnetic over the whole studied temperature range despite the fact that it contains free-radicalo-semiquinone ligands. Such an effect involving electrons belonging to the free-radical ligands is observed for the first time in the magnetochemistry ofd ⁸- andd ⁹-transition-metal complexes. It is explained by incorporation of vacantp _z- and/or occupiedd _xz- andd _yz-orbitals of Ni in molecular orbitals containing the -MO of the semiquinone ligands.Institute of Organometallic Chemistry, Russian Academy of Sciences, 603600 Nizhnii Novgorod, Russia. N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 117907 Moscow, Russia. A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow, Russia. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2315–2323, October, 1992.     

Studies on two cadmium(II) and two zinc(II) complexes of 4′-chloro-2,2′ : 6′,2″-terpyridine with 1 : 1 or 1 : 2 ratio of metal and ligand

The reaction between 4′-chloro-2,2′ : 6′,2″-terpyridine (tpyCl) with d¹⁰ transition-metal ions produced two cadmium(II) and two zinc(II) metal complexes, formulated as [Cd(tpyCl-κ ³ N,N′,N″)(NO₃-κ ² O,O′)(NO₃-κO)(H₂O-κO)] (1), [Cd(tpyCl-κ ³ N,N′,N″)₂](ClO₄)₂ (2), [Zn(tpyCl-κ ³ N,N′,N″)₂](ClO₄)₂ (3), and [Zn(tpyCl-κ ³ N,N′,N″)₂](BF₄)₂ (4). Supramolecular interactions include coordinative bonding, O–H ··· O, O–H ··· Cl, C–H ··· F, and C–H ··· Cl hydrogen bonding and π–π stacking, all of which play essential roles in forming different frameworks of 1–4.     

Syntheses,crystal structures,and fluorescent properties of two d10 metal complexes based on 2-(benzoimidazol-yl)methyl)-1H-1,2,4-triazole and 1,3,5-benzenetricarboxylate

Two d¹⁰ metal complexes, {[Zn(Hbtc)(bmt)]·DMF·5H₂O} _n (1) and {[Cd(Hbtc)(bmt)]·0.5DMF·0.5H₂O} _n (2) (H₃btc?=?1,3,5-benzenetricarboxylic acid, bmt?=?2-((benzoimidazol-yl)methyl)-1H-1,2,4-triazole), have been synthesized under solvothermal conditions by employing bmt and H₃btc. Single-crystal X-ray diffraction shows that Zn(II) ions are connected by bmt with bidentate-bridging coordination and by 1,3,5-benzenetricarboxylate with bis-monodentate coordination leading to the 2D structure of 1. Complex 2 exhibits a 2D layer structure, in which bmt coordinate tridentate-bridging to Cd(II) and 1,3,5-benzenetricarboxylates coordinate to Cd(II) unidentate/chelating. Photoluminescence and thermogravimetric analyses of the two complexes are investigated.     

Electronic state of Fe used as Mössbauer probe in the perovskites LaMO3 (M=Ni and Cu)

For the first time a comparative study of rhombohedral LaNiO₃ and LaCuO₃ oxides, using ⁵⁷Fe Mössbauer probe spectroscopy (1% atomic rate), has been carried out. In spite of the fact that both oxides are characterized by similar crystal structure and metallic properties, the behavior of ⁵⁷Fe probe atoms in such lattices appears essentially different. In the case of LaNi_0.99Fe_0.01O₃, the observed isomer shift (δ) value corresponds to Fe³⁺ (3d⁵) cations in high-spin state located in an oxygen octahedral surrounding. In contrast, for the LaCu_0.99Fe_0.01O₃, the obtained δ value is comparable to that characterizing the formally tetravalent high-spin Fe⁴⁺(3d⁴) cations in octahedral coordination within Fe(IV) perovskite-like ferrates. To explain such a difference, an approach based on the qualitative energy diagrams analysis and the calculations within the cluster configuration interaction method have been developed. It was shown that in the case of LaNi_0.99Fe_0.01O₃, electronic state of nickel is dominated by the d⁷ configuration corresponding to the formal ionic “Ni³⁺-O²⁻” state. On the other hand, in the case of LaCu_0.99Fe_0.01O₃ a large amount of charge is transferred via Cu-O bonds from the O:2p bands to the Cu:3d orbitals and the ground state is dominated by the d⁹L configuration (“Cu²⁺−O” state). The dominant d⁹L ground state for the (CuO₆) sublattice induces in the environment of the ⁵⁷Fe probe cations a charge transfer Fe³⁺+O⁻(L)→Fe⁴⁺+O²⁻, which transforms “Fe³⁺” into “Fe⁴⁺” state. The analysis of the isomer shift value for the formally “Fe⁴⁺” ions in perovskite-like oxides clearly proved a drastic influence of the 4s iron orbitals population on the Fe−O bonds character.     

Isomerization ofn-butane on the SO4/ZrO2 catalyst promoted by IV Period metals

The catalytic activity of superacidic systems based on SO₄/ZrO₂ and modified by IV Period metals in isomerization ofn-butane was studied. At low temperatures of the reaction, the introduction of Fe³⁺, Sc³⁺, Co²⁺, or Zn²⁺ ions (1%) increases the yield of isobutane by 1.5 times due to the activation ofn-butane on the sites created by the promoting ions. The addition of Cr³⁺, V⁴⁺, or Mn²⁺ (1%) decreases the catalytic activity because of a decrease in the catalyst acidity, most likely, due to the reduction of surface sulfur species. The influence of the nature of the support and surface additives of SiO₂, TiO₂, and ZrO₂ on the activity and selectivity of the catalytic system inn-butane isomerization was studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7 pp. 1276–1280, July, 1999     

Melamine-mediated self-assembly of a Cu(II)–methylmalonate complex assisted by π+–π+ and anti-electrostatic H-bonding interactions

A Cu(II)-methylmalonate complex, (C₃H₇N₆)₄[Cu(II)(C₄H₄O₄)₂](H₂O)₄Cl₂ (1) (where C₃H₇N₆ = protonated melamine, C₄H₄O₄ = methylmalonic acid), has been synthesized from aqueous media and its crystal structure was determined by single-crystal X-ray diffraction. The anionic Cu(II)-methylmalonate complex mediated formation of interesting supramolecular assemblies in the solid state by means of ionic interactions with protonated melamine. Moreover, other forces such as antielectrostatic H-bonding and π⁺–π⁺ interactions also play a crucial role in defining the final 3-D architecture of 1. An interesting stacking among protonated melamine molecules is studied by DFT calculations. Lattice water molecules and chlorides form various hydrogen bonds to take part in the self-assembly processes.     

Cation ordering in the fluorite-like transparent conductors In4+xSn3−2xSbxO12 and In6TeO12

The cation ordering in the fluorite-like transparent conductors In_4+xSn_3−2xSb_xO₁₂ and In₆TeO₁₂, was investigated by Time of Flight Neutron Powder Diffraction and X-ray Powder Diffraction (tellurate). The structural results including atomic positions, cation distributions, metal-oxygen distances and metal-oxygen-metal angles point to a progressive cation ordering on both sites of the Tb₇O₁₂-type structure with a strong preference of the smaller 4d¹⁰ cations (Sn⁴⁺, Sb⁵⁺, Te⁶⁺) for the octahedral sites. The corresponding increase of the overall structure-bonding anisotropy is analyzed in terms of the crystal chemical properties of the OM₄ tetrahedral network of the antistructure. The relationships between the M₇O₁₂ and the M₂O₃ bixbyite-type structures are explored. Within the whole series of compositions In_4+xM_3−xO₁₂ (M=Sn, Sb, Te) there exists an increase of the symmetry gap between the more symmetrical bixbyite structure and the M₇O₁₂ type. This is tentatively correlated with the progressive weakening of thermal stability of these compositions from Sn to Te via Sb.     

Molecular and crystal structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.017,18.013,14.08,9.05,10]tetracos-3-yl acetate

The molecular structure of 23,24,25,26,27,29,30-heptamethyl-19,28-oxahexacyclo[15.13.18.0^17,18.0^13,14.0^8,9.0^5,10]tetracos-3-yl acetate III. Compound III C₃₂H₅₂O₃ crystallizes in the monoclinic crystal system with the unit cell parameters a = 13.265(15) ?, b = 6.481(7) ?, c = 32.274(4) ?, β = 99.333(2)°, space group C2, Z = 4, d = 1.176 g/cm³. Original Russian Text Copyright ? 2009 by N. I. Medvedeva, O. B. Flechter, and A. A. Korlyukov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 399–401, March–April, 2009.     

Theory of spin triplet ground states ind 6 transition metal compounds and the effect of high-energy states on the nature of the ground state

The formation of spin triplet, quintet, and singlet ground states within the 3d ⁶ electron configuration is investigated inD _4h , andD _3d symmetries employing irreducible tensor operator methods. Significant differences in the possible ground states are encountered between a complete CI and spin-orbit interaction treatment and an approximate calculation within the cubic⁵ T ₂,¹A₁,³ T ₁, and³ T ₂ parents.     

Theoretical calculations of95Mo-NMR chemical shifts for compounds [MoO4−n S n ]2−

Summary Theoretical calculation of⁹⁵Mo-NMR chemical shifts for [MoO_4–n S _n ]^2– (n=0–4) compounds is reported here for the first time on the basis of Fenske-Hall method and Sum-Over-State (SOS) perturbation theory. A systematic decrease in shielding of⁹⁵Mo nuclei with increase of number of sulfur in [MoO_4–n S _n ]^2–, which is observed experimentally, can be reasonably explained by our calculation. A good linear relationship between chemical shifts of calculation and experiment is obtained. The electronic structure and bonding in these compounds are also discussed.Supported by Nature Science Foundation of China     

ESR study of reversible complex formation between bis(η5-cyclopentadienyl)vanadium and fullerene C60 in solution

Using the ESR method, equilibrium complex formation of fullerene C₆₀ with bis-(⁵-cyclopentadienyl)vanadium in solutions in aromatic solvents was found to occur. Based on an analysis of isotropic (g _i = 2.0008;A _i ,(V⁵¹)=–45.7 mT) and anisotropic (g _i =1.9808;g ₂ = 2.0135; <g ₃> = 2.0060;A ₁(⁵¹V)=–7.85 mT;A ₂(⁵¹V) = –6.50 mT; <A ₃(⁵¹V)> = 0.61 mT) ESR spectra parameters, it was established that the complex formed, Cp₂V(²-C₆₀), corresponds to vanadocene d¹-complexes with ²-bonded ligands.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1945–1947, November, 1994.     

First homo- and hetero-nuclear complexes of a chemical messenger-histamine: Cu(II) complex being a supramolecular assembly based on hydrogen bond, Ni(II)?π and C-H?π non-covalent interactions

In this study, the first homo- and hetero-nuclear cyanocomplexes of histamine (His), namely, [Cu(His)₂][Ni(CN)₄], [Ni(His)₂Ni(CN)₄]_n and [Cd(His)Ni(CN)₄]_n are investigated by X-ray diffraction (XRD) technique, electron paramagnetic resonance (EPR) and infrared (IR) spectroscopy. Besides being the first hetero-nuclear complex of histamine, [Cu(His)₂][Ni(CN)₄] complex has an interesting property as being a supramolecular structure constructed by three different non-covalent interactions as hydrogen bond, Ni(II)?π and C-H?π interactions. In [Cu(His)₂][Ni(CN)₄] complex histamine exists in gauche conformation and N^τ-H tautomeric form, and plays an important role in supramolecular structure formation by participating in non-covalent interactions through its aminoethyl side chain and imidazole group. The shifts and splittings in the stretching vibrations of cyano groups show that [Ni(His)₂Ni(CN)₄]_n and [Cd(His)Ni(CN)₄]_n complexes are one-dimensional and three-dimensional coordination polymers, respectively. In [Ni(His)₂Ni(CN)₄]_n complex, histamine acts as a chelating ligand by adopting gauche conformation. In [Cd(His)Ni(CN)₄]_n complex, Cd(II) ions and [Ni(CN)₄]²⁻ anions form two-dimensional layered structure and histamine has a novel bonding mode as a bridging ligand between these layered structures. It is concluded that histamine may have trans conformation and Nπ-H tautomer as a bridging ligand in [Cd(His)Ni(CN)₄]_n complex, which has not been reported so far for the solid structures of bidentate histamine. EPR studies on [Cu(His)₂][Ni(CN)₄] and Cu²⁺-doped [Cd(His)Ni(CN)₄]_n complexes show that the ground state of the unpaired electron in both complexes is dominantly d_x²-y².