Novel Conductive Radical Cation Salts Based on Methylenediselenotetraselenafulvalene (MDSe-TSF): A Sign of Superconductivity in κ-(MDSe-TSF)2Br Below 4 K

Seven conductive radical cation salts based on MDSe-TSF (methylenediselenotetraselenafulvalene) have been synthesized by electrocrystallization in the presence of Cl⁻, Br⁻, I₃⁻, I₂Br⁻, PF₆⁻, ClO₄⁻, and Cu(NCS)₂⁻ counter anions. The crystal appearances of these salts fairly depend on the anions employed. X-ray crystallographic analyses have revealed that the PF₆ and ClO₄ salts in the shape of brown thin plates adopt the θ-type structures characterized by the herringbone arrangement of donor stacks, whereas the Cl and Br salts in the shape of black thick plates favor the κ-type structures with the orthogonal arrangement of donor dimers. Regardless of different crystal appearances or crystal packing patterns, all these salts show high conductivity (>10² S cm⁻¹) at room temperature and retain metallic properties down to 4.2 K. Of them, the Br salt shows a weak but distinct diamagnetic shielding signal below 4 K in the dc magnetization measurement under zero-field-cooled (ZFC) condition, suggesting a sign of superconductivity. The band calculations of both PF₆ and Br salts demonstrate closed Fermi surfaces indicative of two-dimensional molecular conductors.     

The first BETS radical cation salts with dicyanamide anion: Crystal growth, structure and conductivity study

Electrochemical oxidation of bis(ethylenedithio)tetraselenafulvalene (BETS) has been investigated. Simple and complex dicyanamides of transition metals (Mn²⁺, Ni²⁺ and Fe²⁺) were used as electrolytes. The correlation between composition of prepared radical cation salts and metal nature in electrolytes was established. Manganese dicyanamides provide the formation of BETS salts with the {Mn[N(CN)₂]₃}- and [N(CN)₂]-XH₂O anions. When Ni- or Fe-containing electrolytes were used only metalless BETS salts, α″-BETS₂[N(CN)₂]·2H₂O (I) and θ-BETS₂[N(CN)₂]·3.6H₂O (II), formed. Structures and conducting properties of these salts were analyzed. Both salts exhibit layered structure. Conducting radical cation layers have α″ (I)- or θ-type (II). Anion sheets appear as two-dimensional polymer networks of different types. These networks are formed by [N(CN)]₂⁻ anions and water molecules interlinked by hydrogen bonds. Salt I is a semiconductor and II demonstrates resistance drop down to150 K at normal pressure and down to 72 K at ∼0.4 kbar pressure.     

Synthesis of a new donor, BEDT-HBDST and crystal structures, electrical and magnetic properties of (BEDT-HBDST)2MX4 (M=Fe, Ga, X=Cl, Br), where BEDT-HBDST=2,5-bis(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-2,3,4,5-tetrahydrothiophene

A novel conjugation-elongated bis(ethylenedithio)tetraselenafulvalene (BETS) type donor, 2,5-bis(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-2,3,4,5-tetrahydrothiophene (BEDT-HBDST) and its magnetic and non-magnetic anion salts, (BEDT-HBDST)₂MX₄ (MX₄⁻=FeCl₄⁻, GaCl₄⁻, FeBr₄⁻ and GaBr₄⁻), were prepared. These four salts are isostructural and belong to the space group of P2/c. They showed semiconducting behavior with small activation energies (59-64 meV). The band structures of these salts are quasi one-dimensional and there is a midgap between the upper band and the lower band, since the degree of dimerization is significant in the stacking direction. The MX₄⁻ ions are located between the donor columns and near to the ethylenedithio moieties of the donor molecules. The magnetic susceptibilities of the FeCl₄⁻ and FeBr₄⁻ salts follow the Curie-Weiss law with Curie constants of 4.6 and 4.8 emu K mol⁻¹ (sum of the spins of S=5/2 and S=1/2) and negative Weiss temperatures of θ=−1.2 and −4.9 K, respectively, revealing a weak antiferromagnetic interaction of 3d spins of the FeCl₄⁻ and FeBr₄⁻ anions. The Fe?Fe (6.66-7.60 Å), Cl?Cl (4.81-4.82 Å) and Br?Br (4.74-4.77 Å) distances in the crystal structures of these salts are significantly long. Therefore, the direct magnetic interaction between the 3d spins of the nearest neighboring Fe³⁺ ions appears to be not readily accessible.     

Telluranes: potential synthons for charge-transfer complexes (involving hypervalent Te-I bonds) and serendipitous synthesis of the first triphenyl methyl phosphonium salts containing [C4H8TeI4] and [TeI6]anions

Hypervalent Te-I bonds of telluranes (C₄H₈TeI₂, C₅H₁₀TeI₂ and α-Me₂TeI₂) have been utilised to form the charge transfer (CT) complexes (1-3). The reaction of cyclic tellurane (1,1-diiodotetrahydro tellurophene, C₄H₈TeI₂) with I₂/ICl yields C₈H₁₆Te₂I₆ [IC₄H₈TeI-I-I-ITeC₄H₈I] (1); an unusual dinuclear species while the reaction of another cyclic tellurane (1,1-diiodo telluracyclohexane, C₅H₁₀TeI₂) with I₂ yields C₅H₁₀TeI₄ (2) possessing different structural motif than 1. In 2 the iodine molecules are on both sides bonded to iodine atom of hypervalent Te-I bond of C₅H₁₀TeI₂ which is analogous to the structural type present in Me₂TeI₄ (3) obtained by the reaction of α-Me₂TeI₂ with ICl. The reaction of C₄H₈TeI₂ with PPh₃, serendipitously, yields the first triphenyl methyl phosphonium salts [PPh₃Me]₂ ²⁺[C₄H₈TeI₄]²⁻ (4) and [PPh₃Me]₂ ²⁺[TeI₆]²⁻ (5), indicating the oxidation of PPh₃ whereas C₄H₈TeI₂ itself, is converted into [C₄H₈TeI₄]²⁻ and [TeI₆]²⁻ anions. All the complexes 1-5 have been characterised through single crystal X-ray diffraction studies.     

Electronic band structures and physical properties of ALnTe4 and ALn3Te8 compounds (A=alkali metal; Ln=lanthanoid)

We report about the LMTO-ASA band structure, ELF and COHP calculations for a number of alkali metal rare earth tellurides of the formulas ALnTe₄ (A=K, Rb, Cs and Ln=Pr, Nd, Gd) and KLn₃Te₈ (Ln=Pr, Nd) to point out structure-properties relations. The ALnTe₄ compounds crystallize in the KCeSe₄ structure type with Te ions arranged in the form of 4.3².4.3 nets, in which interatomic homonuclear distances indicate an arrangement of isolated dumbbells. This could be verified by the COHP and ELF calculations, both of which revealed isolated [Te₂] units. But in contrast to the ionic formulation as A⁺Ln³⁺ ([Te₂]²⁻)₂, which can be deduced from this observation, the band structure calculations for KPrTe₄, KNdTe₄, RbNdTe₄ and CsNdTe₄ reveal metallic conductivity. This behavior was verified for KNdTe₄ by resistivity measurements performed by a standard four-probe technique. We explain these results by an incomplete carryover of electrons from the rare earth cation onto tellurium due to covalent bonding leaving parts of the Te-Te ppπ^* antibonding states unoccupied. On the other hand the calculations suggest insulating behavior for KGdTe₄ resulting from a complete filling of the Te-Te ppπ^* antibonding states due to the increased stability of the half filled 4f shell. The ALn₃Te₈ compounds crystallize in the KNd₃Te₈ structure type, a distorted addition-defect variant of the NdTe₃ type with 4⁴ Te nets. As polyanionic fragments L-shaped [Te₃]²⁻ and infinite zig-zag chains _∞¹[Te₄]⁴⁻ are observed (with interatomic homonuclear distances in the range 2.82-3.00 Å), which are separated from each other by distances in the range 3.27-3.49 Å. Again COHP calculations made evident that these latter interactions are secondary. Within the infinite zig-zag chains _∞¹[Te₄]⁴⁻ the Te ions at the corners of the chain have a higher negative charge than the linear coordinated ones in the middle. KPr₃Te₈ and KNd₃Te₈ are semiconductors, verified for the latter by resistivity measurements.     

BETS-Based Molecular Conductors with Tetrahedral Anions TlCl4 –, MnBr4 2–, CoCl4 2– (BETS = Bis(ethylenedithio)tetraselenafulvalene)

Molecular conductors on the basis of bis(ethylenedithio)tetraselenafulvalene (BETS) with tetrahedral anions TlCl₄ ^–, MnBr₄ ^2–, and CoCl₄ ^2– were synthesized and studied by X-ray diffraction analysis. The salts under study exhibit various conducting properties: -(BETS)₂TlCl₄ (I) is a superconductor with T _c = 2.5 K, -(BETS)₄MnBr₄ · 2C₂H₅OH (II) is a metal up to 30 K, while (BETS)₂CoCl₄ (III) is a dielectric. Salt I has -packing of the donor molecules, salt II has -packing, whereas salt III has no conducting layers. These structural differences are mainly the reasons for different conducting properties of compounds I–III.     

Tetrachloroferrate (III) Salts of BDH-TTP [2,5-Bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] and BDA-TTP [2,5-Bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene]: Crystal Structures and Physical Properties

Three FeCl₄ salts based on non-tetrathiafulvalene (TTF) donors, 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP) and 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP), have been prepared and characterized as κ-(BDH-TTP)₂FeCl₄, β-(BDA-TTP)₂FeCl₄, and (BDA-TTP)₃FeCl₄ · PhCl. The κ-(BDH-TTP)₂FeCl₄ salt, with a room-temperature conductivity (σ_rt) of 39 S cm⁻¹, is metallic down to 1.5 K, and its magnetic susceptibility obeys the Curie-Weiss law with a Curie constant (C) of 4.25 emu K mol⁻¹ and a Weiss constant (θ) of 0.041 K. β-(BDA-TTP)₂FeCl₄ exhibits metallic behavior (σ_rt=9.4 S cm⁻¹) with a sharp metal-to-insulator (MI) transition (T_MI=113 K) and antiferromagnetic ordering with the Néel temperature of near 8.5 K, whereas the solvated (BDA-TTP)₃FeCl₄ · PhCl salt is a semiconductor with a thermal activation energy of 0.11 eV (σ_rt=2.0× 10⁻² S cm⁻¹) and exhibits Curie-Weiss behavior (C=4.42 emu K mol⁻¹, θ=−0.35 K).     

The supramolecular chemistry of metal complexes with heavily substituted imidazoles as ligands: Cobalt(II) and zinc(II) complexes of 1-methyl-4,5-diphenylimidazole

An investigation of the M^II/X⁻/L [M^II = Co, Ni, Cu, Zn; X⁻ = Cl⁻, Br⁻, I⁻, NCS⁻, NO₃⁻, N₃⁻, CH₃COO⁻; L = 1-methyl-4,5-diphenylimidazole] general reaction system towards the detailed study of the intermolecular interactions utilized for controlling the supramolecular organization and the structural consequences on the structures produced has been initiated. Three representative complexes with the formulae [Co(NO₃)₂(L)₂] (1), [Zn(NO₃)₂(L)₂] (2) and [Co(NCS)₂(L)₂]·EtOH (3·EtOH) have been synthesized and characterized by spectroscopic methods and single-crystal X-ray analysis. Compounds 1 and 2 are isomorphous (tetragonal, I4₁cd) with their metal ions in a severely distorted octahedral Co/ZnN₂O₄ environment, while 3·EtOH crystallizes in P2₁/c with a tetrahedral CoN₄ coordination. The structural analysis of 1, 2 and 3·EtOH reveals a common mode of packing among neighbouring ligands (expressed through intramolecular π–π interactions between the 4,5-diphenylimidazole moieties), enhancing thus the rigidity and stability of the complexes. The bent coordination of the two isothiocyanates in 3 [Co–NCS angles of 173.8(2) and 160.8(2)°] seems to be caused by intermolecular hydrogen bonding and crystal packing effects.     

Syntheses, crystal and electronic structures of three new potassium cadmium(II)/zinc(II) tellurides: K2Cd2Te3, K6CdTe4 and K2ZnTe2

Three new ternary potassium(I) zinc(II) or cadmium(II) tellurides, namely, K₂Cd₂Te₃, K₆CdTe₄ and K₂ZnTe₂, were synthesized by solid-state reactions of the mixture of pure elements of K, Cd (or Zn) and Te in Nb tubes at high temperature. K₂Cd₂Te₃ belongs to a new structure type and its structure contains a novel two-dimensional [Cd₂Te₃]²⁻ layers perpendicular to the b-axis. K(5) cation is located at the center of five member rings of the 2D [Cd₂Te₃]²⁻ layer, whereas other K⁺ cations occupy the interlayer space. K₆CdTe₄ with a K₆HgS₄ type structure features a “zero-dimensional” structure composed of isolated CdTe₄ tetrahedra separated by the K⁺ ions. K₂ZnTe₂ in the K₂ZnO₂ structural type displays 1D [ZnTe₂]²⁻ anionic chains of edge sharing [ZnTe₄] tetrahedra separated by the potassium(I) ions. K₂Cd₂Te₃, K₆CdTe₄ and K₂ZnTe₂ revealed a band gap of 1.93, 2.51 and 3.0 eV, respectively.     

Thermodynamic Studies on NdFeO3(s)

The enthalpy increments and the standard molar Gibbs energy of formation of NdFeO₃(s) have been measured using a high-temperature Calvet microcalorimeter and a solid oxide galvanic cell, respectively. A λ-type transition, related to magnetic order-disorder transformation (antiferromagnetic to paramagnetic), is apparent from the heat capacity data at ∼687 K. Enthalpy increments, except in the vicinity of transition, can be represented by a polynomial expression: {H°_m(T)−H°_m(298.15 K)}/J·mol⁻¹ (±0.7%)=−53625.6+146.0(T/K) +1.150×10⁻⁴(T/K)² +3.007×10⁶(T/K)⁻¹; (298.15≤T/K ≤1000). The heat capacity, the first differential of {H°_m(T)−H°_m(298.15 K)} with respect to temperature, is given by C^o_{p, m}/J·K⁻¹·mol⁻¹=146.0+2.30×10⁻⁴(T/K)−3.007×10⁶(T/K)⁻². The reversible emf's of the cell, (−) Pt/{NdFeO₃(s) +Nd₂O₃(s)+Fe(s)}//YDT/CSZ//{Fe(s)‘FeO’(s)}/Pt(+), were measured in the temperature range from 1004 to 1208 K. It can be represented within experimental error by a linear equation: E/V:(0.1418±0.0003)−(3.890±0.023)×10⁻⁵(T/K). The Gibbs energy of formation of solid NdFeO₃ calculated by the least-squares regression analysis of the data obtained in the present study, and data for Fe_0.95O and Nd₂O₃ from the literature, is given by Δ_fG°_m(NdFeO₃, s)/kJ·mol⁻¹(±2.0)=−1345.9+0.2542(T/K); (1000≤T/K ≤1650). The error in Δ_fG°_m(NdFeO₃, s, T) includes the standard deviation in emf and the uncertainty in the data taken from the literature. Values of Δ_fH°_m(NdFeO₃, s, 298.15 K) and S°_m(NdFeO₃, s, 298.15 K) calculated by the second law method are −1362.5 (±6) kJ·mol⁻¹ and 123.9 (±2.5) J·K⁻¹·mol⁻¹, respectively. Based on the thermodynamic information, an oxygen potential diagram for the system Nd-Fe-O was developed at 1350 K.     

Solvatochromism, hyperpolarizability, molecular and crystal structure of betaine dye 4-(2,4,6-triphenylpyridinium-1-yl)-phenolate

Solvatochromic effect of 4-(2,4,6-triphenylpyridinium-1-yl)-phenolate hydrate, 1, was determined. CT absorption band, which gave the shift from 23,880 (in water solution) to 14,440 cm⁻¹ (in anisole solution) allowed the molecular second order polarizability β_CT to be estimated as 59.5×10⁻³⁰ cm⁵ esu⁻¹. The crystal structure of 1 was determined: C₂₉H₂₁NO·5.78H₂O; orthorhombic, C222₁, a=15.005(9), b=24.356(4), c=7.5097(9) Å; V=2744.5(17) Å³, Z=4, D_X=1.224 g cm⁻¹; λ=0.71073 Å (Mo Kα); μ=0.087 mm⁻¹; final R₁=0.0551 for 2882 reflections [I>2σ(I)]. The molecules of 1, in an anti-parallel arrangement, form columns along the c-axis through stacking between the pyridinium ring and a phenyl ring in para position of the neighbouring molecule. Water molecules filling channels between the columns are disordered. Two of water molecules are connected by hydrogen bonds with negatively charged oxygen atom of 1. Powdered samples of 1 revealed only weak SHG response as measured using HRS method in relation to urea standard.     

Quasi-two-dimensional organic metals with differently oriented conducting layers

New layered organic conductors based on selenium- and sulfur-containing donor molecules of bis(ethylenedithio)tetraselenafulvalene (BETS) and deuterated bis(ethylenedithio)-tetrathiafulvalene (ET) with tetrahedral anions of divalent metals of the general formula (BETS)₄HgBr₄(1,2-C₆H₄Cl₂), (ET-d₈)₄HgBr₄(C₆H₄Cl₂) and (ET-d₈)₄HgBr₄(C₆H₅X) (where X = Cl, Br) were synthesized using halobenzenes as solvents. The crystal structure of (BETS)₄HgBr₄(C₆H₄Cl₂) was studied at room temperature. A distinctive feature of the crystal structures of the compounds is the alternation of the conducting layers, which differ in direction of the radical cation stacks. The conductivity along the layers is of metallic character with the temperature decrease down to 4.3 K for (BETS)₄HgBr₄(C₆H₄Cl₂) and down to 40—105 K for ET-d₈-based compounds, while in the direction perpendicular to the conducting layers the conductivity is semiconducting. A comparative analysis of the temperature dependence of the resistivity for the compounds (ET)₄HgBr₄(Solvent) (Solvent is 1,2-C₆H₄Cl₂, C₆H₅X), which are based on ET and its deuterated analog, allows one to suggest that the metal—metal phase transitions observed in the 220—285 K range are of different origin: in the compounds containing 1,2-C₆H₄Cl₂ they are due to the ordering of solvent molecules, whereas in the compounds containing C₆H₅X the transitions are associated with rearrangements of the terminal ethylene groups.     

New open-framework in the uranyl vanadates A3(UO2)7(VO4)5O (A=Li, Ag) with intergrowth structure between A(UO2)4(VO4)3 and A2(UO2)3(VO4)2O

New uranyl vanadates A₃(UO₂)₇(VO₄)₅O (M=Li (1), Na (2), Ag (3)) have been synthesized by solid-state reaction and their structures determined from single-crystal X-ray diffraction data for 1 and 3. The tetragonal structure results of an alternation of two types of sheets denoted S for _∞²[UO₂(VO₄)₂]⁴⁻ and D for _∞²[(UO₂)₂(VO₄)₃]⁵⁻ built from UO₆ square bipyramids and connected through VO₄ tetrahedra to _∞¹[U(3)O₅-U(4)O₅]⁸⁻ infinite chains of edge-shared U(3)O₇ and U(4)O₇ pentagonal bipyramids alternatively parallel to a- and b-axis to construct a three-dimensional uranyl vanadate arrangement. It is noticeable that similar _∞[UO₅]⁴⁻ chains are connected only by S-type sheets in A₂(UO₂)₃(VO₄)₂O and by D-type sheets in A(UO₂)₄(VO₄)₃, thus A₃(UO₂)₇(VO₄)₅O appears as an intergrowth structure between the two previously reported series. The mobility of the monovalent ion in the mutually perpendicular channels created in the three-dimensional arrangement is correlated to the occupation rate of the sites and by the geometry of the different sites occupied by either Na, Ag or Li. Crystallographic data: 293 K, Bruker X8-APEX2 X-ray diffractometer equipped with a 4 K CCD detector, MoKα, λ=0.71073 Å, tetragonal symmetry, space group P4¯m2, Z=1, full-matrix least-squares refinement on the basis of F²; 1,a=7.2794(9) Å, c=14.514(4) Å, R1=0.021 and wR2=0.048 for 62 parameters with 782 independent reflections with I?2σ(I); 3, a=7.2373(3) Å, c=14.7973(15) Å, R1=0.041 and wR2=0.085 for 60 parameters with 1066 independent reflections with I?2σ(I).     

1D coordination polymers of silver(I) and copper(II) based on bis(N-heterocyclic carbene) ligands: Synthesis and structural studies

The alkyl chain-linked diimidazolium (or dibenzimidazolium) salts, 1,1′-diethyl-4,4′-tetramethylene-diimidazolium-diiodide (L¹H₂·I₂) and 1,1′-diethyl-3,3′-trimethylene-dibenzimidazolium-diiodide (L²H₂·I₂), and their silver(I) and copper(II) coordination polymers, [L¹AgI]_n (1) and [L²Cu₂I₄]_n (2), have been prepared and characterized. Complex 1 is a 1D helical polymer generated by bidentated carbene ligands (L¹) and Ag(I) atoms. The 1D polymer of 2 is formed by bidentated carbene ligands (L²) and coplanar quadrilateral Cu₂I₂ units. 3D supramolecular frameworks in the crystal packings of 1 and 2 are formed via intermolecular weak interactions, including C–H···π contacts, π–π interactions and C–H···I hydrogen bonds.     

Crystal and molecular structure of organic semiconductor (ET)8[Hg4Cl12] · 2C6H6

A new organic semiconductor, (ET)₈[Hg₄C1₁₂] · 2C6H6, obtained in the ET⁺-HgCl ₃ ^– -PhF system has been studied by X-ray structural analysis. Radical cations of bis(ethylenedithio)tctrathiafulvalene (ET) in the organic layer of the structure are packed in stacks ofa-type. The average angle between the planes of ET cations from adjacent stacks is 50.1°. The anionic layer is formed by four-charge centrosymmetric [Hg₄Cl₁₂]^4– complexes and benzene solvate molecules. A comparative crystal-chemical study of the salts obtained by the reaction in the ET⁺-HgX ₃ ^– -PhY system (where X = Cl, Br, and I; Y = F, Cl, and Br) made it possible to reveal a substantial effect of the sizes of the X and Y atoms on the composition of the salts and on the structural characteristics of the layers, which are responsible for the various conductivities of these salts.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 386–391, February, 1996     

Solid chemistry of the Zn/1,2,4-triazolate/anion system: Separation of 2D isoreticular layers tuned by the terminal counteranions X (X=Cl, Br, I, SCN)

An array of 2D isoreticular layers, viz. [Zn(atrz)X]_∞ (1·X; X=Cl⁻, Br⁻, I⁻; atrz=3-amino-1,2,4-triazole anion), [Zn₄(atrz)₄(SCN)₄·H₂O]_∞ (1·SCN·H₂O) and [Zn(trz)X]_∞ (2·X; X=Cl⁻, Br⁻, I⁻; trz=1,2,4-triazole anion), have been hydrothermally synthesized and structurally characterized. Compounds 1·X and 1·SCN·H₂O are constructed from binuclear planar Zn₂(atrz)₂ subunits and exhibit (4,4) topological network when the subunits are simplified as four-connected nodes. Based on changing the terminal counteranions X (X=Cl⁻, Br⁻, I⁻, SCN⁻), the average interlayer separations of 1·X and 1·SCN·H₂O are enlarged, which equal to 5.851, 6.153, 6.651 and 8.292 Å, respectively. As a result, H₂O molecules reside in the spaces between two adjacent layers of 1·SCN·H₂O. 2 and 1 are the isomorphous structures. In common with 1, the interlayer separations of 2·X are widened with increasing the ion radius. Solid-state luminescence properties and thermogravimetric analyses of 1 and 2 were investigated, respectively.     

Synthesis, crystal and electronic structure, and physical properties of the new lanthanum copper telluride La3Cu5Te7

The new lanthanum copper telluride La₃Cu_5−xTe₇ has been obtained by annealing the elements at 1073 K. Single-crystal X-ray diffraction studies revealed that the title compound crystallizes in a new structure type, space group Pnma (no. 62) with lattice dimensions of a=8.2326(3) Å, b=25.9466(9) Å, c=7.3402(3) Å, V=1567.9(1) Å³, Z=4 for La₃Cu_4.86(4)Te₇. The structure of La₃Cu_5−xTe₇ is remarkably complex. The Cu and Te atoms build up a three-dimensional covalent network. The coordination polyhedra include trigonal LaTe₆ prisms, capped trigonal LaTe₇ prisms, CuTe₄ tetrahedra, and CuTe₃ pyramids. All Cu sites exhibit deficiencies of various extents. Electrical property measurements on a sintered pellet of La₃Cu_4.86Te₇ indicate that it is a p-type semiconductor in accordance with the electronic structure calculations.     

The structures of (phenylato)(N-2-thiophenecarboxamido-meso-tetraphenylporphyrinato)mercury(II) and bisphenylmercury(II) complex of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-tetraphenylporphyrin

The reaction of PhHgOAc with N-NHCO-2-C₄H₃S-Htpp (5) and N-p-HNSO2C6H4^tBu-Htpp (4) gave a mercury (II) complex of (phenylato) (N-2-thiophenecarboxamido-meso-tetra phenylporphyrinato)mercury(II) 1.5 methylene chloride solvate [HgPh(N-NHCO-2-C₄H₃S-tpp) · CH₂Cl₂ · 0.5C₆H₁₄;  6 · CH₂Cl₂ · 0.5C₆H₁₄] and a bismercury complex of bisphenylmercury(II) complex of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-tetraphenylporphyrin, [(HgPh)2(N-p-NSO₂C₆H₄^tBu-tpp); 7], respectively. The crystal structures of 6 · CH₂Cl₂ · 0.5C₆H₁₄ and 7 were determined. The coordination sphere around Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and Hg(2) in 7 is a sitting-atop derivative with a seesaw geometry, whereas for the Hg(1) in 7, it is a linear coordination geometry. Both Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and Hg(2) in 7 acquire 4-coordination with four strong bonds [Hg(1)–N(1) = 2.586(3) Å, Hg(1)–N(2) = 2.118(3) Å, Hg(1)–N(3) = 2.625(3) Å, and Hg(1)–C(50) = 2.049(4) Å for 6 · CH₂Cl₂ · 0.5C₆H₁₄; Hg(2)–N(1) = 2.566(6) Å, Hg(2)–N(2) = 2.155(6) Å, Hg(2)–N() = 2.583(6) Å, and Hg(2)–C(61) = 2.064(7) Å for 7]. The plane of the three pyrrole nitrogen atoms [i.e., N(1)–N(3)] strongly bonded to Hg(1) in 6 · CH₂Cl₂ · 0.5C₆H₁₄ and to Hg(2) in 7 is adopted as a reference plane 3N. For the Hg²⁺ complex in 6 · CH₂Cl₂ · 0.5C₆H₁₄, the pyrrole nitrogen bonded to the 2-thiophenecarboxamido ligand lies in a plane with a dihedral angle of 33.4° with respect to the 3N plane, but for the bismercury(II) complex in 7, the corresponding dihedral angle for the pyrrole nitrogen bonded to the NSO₂C₆H₄^tBu group is found to be 42.9°. In the former complex, Hg(1)²⁺ and N(5) are located on different sides at 1.47 and −1.29 Å from its 3N plane, and in the latter one, Hg(2)²⁺ and N(5) are also located on different sides at −1.49 and 1.36 Å form its 3N plane. The Hg(1)?Hg(2) distance in 7 is 3.622(6) Å. Hence, no metallophilic Hg(II)?Hg(II) interaction may be anticipated. NOE difference spectroscopy, HMQC and HMBC were employed to unambiguous assignment for the ¹H and ¹³C NMR resonances of 6 · CH₂Cl₂ ·  0.5C₆H₁₄ in CD₂Cl₂ and 7 in CDCl₃ at 20 °C. The ¹⁹⁹Hg chemical shift δ for a 0.05 M solution of 7 in CDCl₃ solution is observed at −1074 ppm for Hg(2) nucleus with a coordination number of four and at −1191 ppm for Hg(1) nucleus with a coordination number of two. The former resonance is consistent with that chemical shift for a 0.01 M solution of 6 in CD₂Cl₂ having observed at −1108 ppm for Hg(1) nucleus with a coordination number of four.     

Crystal structure, spectroscopy and magnetism of trinuclear nickel(II), cobalt(II) complexes and their solid solution

Four new complexes [Ni₃(μ-L)₆(H₂O)₆](NO₃)₆·6H₂O (1), [Co₃(μ-L)₆(H₂O)₆](NO₃)₆·6H₂O (2), [Ni₃(μ-L)₆(H₂O)₄(CH₃OH)₂](NO₃)₆·4H₂O (3), [Co₃(μ-L)₆(H₂O)₄(CH₃OH)₂](NO₃)₆·4H₂O (4) (L = 4-amino-3,5-dimethanyl-1,2,4-triazole) were synthesized and structurally characterized by X-ray single-crystal diffraction. The structural analyses show that complex 1 and 2 are isomorphous; complex 3 and 4 are isomorphous. Four complexes all consist of the linear trinuclear cations ([M₃(μ-L)₆(H₂O)₆]⁶⁺ (M = Ni,Co) for 1 and 2; [M₃(μ-L)₆(H₂O)₄(CH₃OH)₂]⁶⁺ (M = Ni,Co) for 3 and 4), NO₃⁻ anions and crystallized water molecules. In the trinuclear cations, the central M(II) ions and two terminal M(II) ions are bridged by three triazole ligands. Other eleven solid solution compounds which are isomorphous with complex 3 and 4 were obtained by using different ratio of Ni(II) and Co(II) ions as reactants and ICP result indicates that ligand L has higher selectivity of Ni(II) ions than that of Co(II) ions. The magnetic analysis was carried out by using the isotropic spin Hamiltonian ? = −2J(?₁?₂ + ?₂?₃) (for complexes 1 and 3) and simultaneously considering the temperature dependent g factor (for complexes 2 and 4). Both the UV-Vis spectra and the magnetic properties of the solid solutions can be altered systematically by adjusting the Co(II)/Ni(II) ratio.