Trigonal Pyramidal Coordination Research Articles

Markwelchite, TlPbSbS3, a new Tl–Pb sulfosalt from the hydrothermal deposit of Jas Roux, Hautes-Alpes, France

AbstractMarkwelchite, ideally TlPbSbS3, is a new mineral from the hydrothermal deposit of Jas Roux, Hautes-Alpes, France. It occurs as a black anhedral crystal associated closely with protochabournéite. Microhardness measurements (VHN15) gave a mean value of 197 kg/mm2 corresponding to a Mohs hardness of ~3–4. In plane-polarised incident light, markwelchite is grey in colour. Under crossed polars, it is distinctly anisotropic with greyish white to bluish rotation tints, with bright red internal reflections. Reflectance percentages (Rmin and Rmax) are: 28.5, 31.5 (471.1 nm); 28.3, 30.7 (548.3 nm); 27.9, 30.3 (586.6 nm); and 27.6, 29.8 (652.3 nm). The mean of 5 electron microprobe spot analyses gave Tl 34.67(45), Pb 31.86(25), Sb 15.06(15), As 2.37(5), S 15.35(20), total 99.31 wt.%, corresponding, on the basis of a total of 6 atoms per formula unit and structural results, to Tl1.063Pb0.964(Sb0.775As0.198)Σ0.973S3.000. Single-crystal X-ray diffraction studies revealed that markwelchite is isotypic with richardsollyite, TlPbAsS3. It is monoclinic, space group P21/c, with the following unit-cell parameters: a = 8.9144(3), b = 8.4513(3), c = 8.6511(3) Å, β = 108.723(4)°, V = 617.27(4) Å3 and Z = 4. The five strongest observed powder-diffraction lines [d in Å (Irel)(hkl)] are: 3.88 (100)($\bar{2}$11); 3.78 (90)(210); 3.29 (90)(102); 2.73 (85)($\bar{1}$13); and 2.93 (75)(022). The crystal structure can be described as formed by (100) [Me2(SbS3)]– layers sandwiching the Me1+ cations. The Me1 site has a seven-fold coordination, whereas the Me2 site has an 6+2 coordination corresponding to a distorted, bicapped trigonal prismatic coordination, and the Sb site displays a trigonal pyramidal coordination with three S atoms and Sb at the apex.The name markwelchite honours Dr Mark D. Welch of the Natural History Museum, London, UK.The new mineral has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2024–001). A discussion on the relationships between markwelchite and synthetic TlPbSbS3 is also provided.

Coordination of Pnictogenylboranes Towards Tl(I) Salts and a Tl- Mediated P-P Coupling.

The coordination chemistry of only Lewis-base (LB)-stabilized pnictogenylboranes EH2 BH2 ⋅NMe3 (E=P, As) towards Tl(I) salts has been studied. The reaction of Tl[BArCl ] (BArCl =[B(3,5-C6 H3 Cl2 )4 ]- ) with the corresponding pnictogenylborane results in the formation of [Tl(EH2 BH2 ⋅NMe3 )][BArCl ] (1 a: E=P; 1 b: E=As). Whereas the Tl ion in 1 a/b is monocoordinated, the exchange of the weakly coordinating anion (WCA) in the Tl(I) salt leads to the formation of a trigonal pyramidal coordination mode at the Tl atom by coordination of three equivalents of EH2 BH2 ⋅ NMe3 in [Tl(EH2 BH2 ⋅ NMe3 )3 ][WCA] (2 a: E=P, WCA=TEFCl ; 2 b: E=As, WCA=TEF) (TEF=[Al{OC(CF3 )3 }4 ]- , TEFCl =[Al{(OC(CF3 )2 (CCl3 )}4 ]- ). Furthermore, by using two equivalents of PH2 BH2 ⋅NMe3 , a Tl(I)-mediated P-P coupling takes place in CH2 Cl2 as solvent resulting in [Me3 N⋅BH2 PH2 PHBH2 ⋅NMe3 ][WCA] (WCA=TEF, 3 a; BArCl , 3 b; TEFCl , 3 c). In contrast, for the arsenic derivatives 1 b and 2 b, no coupling reaction is observed. The underlying chemical processes are elucidated by quantum chemical computations.

Construction and identification of highly active single-atom Fe1-NC catalytic site for electrocatalytic nitrate reduction

Atomically dispersed metal-N-C sites are highly active and selective for nitrate reduction reaction (NO3RR), while identifying their coordination and geometry structures remains significantly challenging. In this study, thermal-modulated single-atom Fe-based catalysts were fabricated and applied in NO3RR. The coordination and geometry structures of metal active-site in the Fe1/NC-X (X is the pyrolysis temperature) catalysts were elaborately dissected. The results disclose that Fe1/NC-900 with trigonal pyramidal Fe-N3 coordination exhibits the highest NO3RR performance with an ammonia yield rate (YR) of 18.8 mgNH3 h−1 mgcat−1 at − 0.9 V, and a Faradaic efficiency (FE) of 86% at − 0.7 V vs RHE. Electrochemical operando attenuated total reflection surface-enhanced infrared absorptive spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculation demonstrate that the Fe-N3 coordination in Fe1/NC-900 are responsible for the much higher catalytic activity in NO3RR due to their lone pair electrons, stronger charge transfer, and lower energy barrier of the rate-determining step.

Synthesis of bis(2-pyrazinyl)selenide and its coordination polymer with silver(I) via both solution and solventless mechanochemical grinding route

Synthesis and characterization of an organo-selenium compound, bis(pyrazinyl)selenide is presented which was further employed as a linker for silver(I) coordination polymer. Accordingly, it was reacted with AgBF4 to obtain its coordination polymer of composition, [Ag(pyz2Se)](BF4)·H2O. Crystallographic structure elucidation reveals that the resulting compound is a two-dimensional coordination polymer. Each silver(I) centre possesses coordination number of 5, defined by two selenium and three nitrogen donors, and it constitutes in a distorted trigonal pyramidal coordination sphere. One pyrazinyl ring bridges two Ag(I) by both of its N-atoms, while for other pyrazinyl ring, only N-atom participate in coordination. The BF4− anion present in the lattice balances the charge. In addition, there is a water molecule present in the crystal lattice. The idle N-atom, which does not take part in coordination, forms hydrogen bonding interaction with the water molecule. More interestingly, this coordination polymer can be obtained just by grinding the ingredients on a mortar, which offer a solventless green synthesis.

1-(2,6-dimethylphenyl)-5-allylsulfanyl-1H-tetrazole and its copper(I) tetrafluoroborate n,σ-complex: synthesis, structure and quantum-chemical calculations

1-(2,6-Dimethylphenyl)-5-allylsulfanyl-1 H -tetrazole ( o-dmphast ) and its copper(I) tetrafluoroborate p,σ-complex [Cu 2 ( o-dmphast ) 2 (BF 4 ) 2 ] ( 1 ) were synthesized and X-ray structurally studied. o-Dmphast was prepared in several stages by known protocol, starting from 2,6-dimethyl aniline. The single crystals of 1 were obtained by means of the alternating-current electrochemical technique. The collected diffraction data were processed using CrysAlis RED program. The structures were solved by ShelXT program and refined by least squares method on F 2 by ShelXL program with the following graphical user interface of OLEX 2 . Compound 1 crystallizes in the centrosymmetric space group : a = 7.405(3)), b = 7.786(3), c = 11.625(4) Å, a = 101.90(3) , β = 100.88(3) , g = 104.81(3) , V = 613.0(4) Å 3 , Z = 2. π-Complexe crystallizes in the centrosymmetric space group P 2 1 /n .: a = 9.271(3), b = 14.171(4), c = 11.956(4) Å, β = 91.52(3) , V = 1570.2(9) Å 3 , Z = 2. Allylsulfanyl group of o-dmphast has synclinal conformation relative to the S1—C3 bond and antisynclinal conformation relative to the C2—C3 bond (the corresponding torsion angles C5—S1—C3—C2 and S1—C3—C2—C1 are 76.5(2) and –118.0(3)). In the structure of o-dmphast , the hydrogen atom of the one methyl group (C13) and the hydrogen atom of the methylene group of the allyl substituent form weak С−H···N hydrogen bonds with the nitrogen atoms of the tetrazole ring of neighboring molecules. Tetrazole rings of the nearest molecules are involved in the π···π-stacking interaction at a distance of 3.44 Å. Structure of 1 is built of centrosymmetric dimers which are formed by coordination to two Cu + ions of two chelate-bridging molecules o-dmphast . The dimeric moieties contain a six-membered {Cu 2 N 4 } ring comprised of two pairs of [ - N - N - ] tetrazole fragments. π-Coordinated Cu(I) cation adopts a close to a trigonal pyramidal coordination environment (2N, (C=C) + F). The corresponding four-coordinate geometry indexes τ 4 is 0.78. Copper(I) ion and allylic group (C1, C2 and С3 atoms) in 1 are disordered over two sites with an occupancy ratio of 0.522(4):0.478(4). Fluorine atoms of the anion are also disordered over two sites with an occupancy ratio of 0.737(3):0.263(3). To further analyse the intermolecular interactions in the structures of o-dmphast , Hirshfeld surface analysis and energy framework computational analysis have been performed. Keywords: copper(I), π-complex, allyl derivative of tetrazole, crystal structure, quantum-chemical calculations.

Copper(I) halide complexes with n,n’-diallylthiomorpholinium chloride: synthesis and crystal structure

By means of alternating current electrochemical technique, basing on ethanolic solutions of CuCl 2 ·2H 2 O or CuBr 2 and N,N’-diallylthiomorpholinium chloride, the two isostructural s-complexes of [C 4 H 8 NS(C 3 H 5 ) 2 Cu Hal 2 ] composition were obtained in a single crystal form and characterized by X-ray single crystal method: sp. gr. P 2 1 / c , Z = 4, Hal = Cl ( І ) – a = 7.7763(4), b = 13.1892(5), c = 13.1761(6) Å, β = 103.470(5)°, V = 1314.2(1) Å 3 , r calc. = 1.611 g/сm 3 , m (MoK a ) = 2.20 mm −1 , q max. = 28.8°, 10141 measured, 2659 used reflections, R ( F 2 ) = 0.032, S = 1.07; Hal = 1,04Br/0,96Cl ( ІІ ) – a = 7.9771(3), b = 13.2391(5), c = 13.1422(5) Å, β = 103.942(4), V = 1347.1(1) Å 3 , r calc. = 1.80 g/см 3 , m (MoK a ) = 5.02 mm −1 , q max. = 29.0°, 21269 measured, 2772 used reflections, R ( F 2 ) = 0.027, S = 1.08. In the crystal structure of the studied compounds, the trigonal-pyramidal coordination environment of Cu(I) includes sulfur atoms of the organic cation and three chloride anions (compound I ) or chloride/bromide mixture (compound II ). Atoms occupying position Hal (2) perform a bridging function and connect individual coordination polyhedrons into dimeric topological units {L 2 Cu 2 Hal 4 }. These dimers through hydrogen bonding are linked into a three-dimensional framework. None of the available allylic groups of the N,N’-diallylthiomorpholinium cation are coordinated to the copper(I) ion. In our opinion, this feature of the discussed crystal structure of [(C 4 H 8 NS(C 3 H 5 ) 2 )Cu Hal 2 ] compounds is explained by the influence of competition between the sulfur atom and the C=C bond of the allyl group of the cation during complexation in solution and the redistribution of electron density in the crystal structure of solid compounds due to hydrogen contacts C–H… Hal . Keywords : N,N’-diallylthiomorpholinium; copper(І); s-complexes; crystal structure.

Anion Induced Synthesis, Structural Characterization and Antibacterial Activity of Zinc(II) Complexes Derived from 5-Bromo-2-((2-(diethylamino)ethylimino)methyl) phenol

By changing the anions of zinc salts, three different zinc(II) complexes, [Zn2(HL)2(NCS)4]·2CH3OH (1), [Zn2L(μ2-η1:η1-CH3COO)2(NCS)] (2) and [Zn(HL)I2]·CH3OH (3), where L = 5-bromo-2-((2-(diethylamino)ethylimino)methyl)phenolate, HL = 5-bromo-2-((2-(diethylammonio)ethylimino)methyl)phenolate, have been synthesized and characterized by IR and UV-Vis spectroscopy, as well as single-crystal X-ray diffraction. X-ray analysis indicates that the Zn atoms in the complexes are in trigonal bipyramidal, square pyramidal and tetrahedral coordination. The anions of the zinc salts lead to the formation of different structures of the complexes. Antibacterial activity of the complexes against Staphylococcus aureus, Escherichia coli, Klebsielle pneumoniae and Candida albicans strains was studied.

Silver(I) complexes based on diorganoselenium(II) ligands with amino or hydroxo functionalities

The diorganoselenide [Me2C(OH)CH2]2Se (1) was prepared by reacting the in situ obtained Na2Se with 1‐chloro‑2‐methyl‐2‐propanol. Reactions of 1 and [2-(Me2NCH2)C6H4]2Se (2) with appropriate silver(I) salts in 1:1 molar ratio resulted in metal complexes of type [Ag(X)Se{CH2C(OH)Me2}2] [X = OSO2CF3 (OTf) (3), OClO3 (4)] and [Ag(X)Se{C6H4(CH2NMe2)-2}2] [X = OSO2CF3 (5), ONO2 (6)], respectively. The ligand 1 and the silver complexes were investigated by appropriate spectroscopic methods, both in solution and in solid state: multinuclear NMR (1H, 13C, 19F, 77Se), ESI+ mass spectrometry, IR spectroscopy and molar conductivity. The metal complexes behave as 1:1 electrolytes in 10−3 MeOH solutions, while in solid state the anionic ligands behave as monodentate moieties. Complexes 4 and 5 were investigated by single‐crystal X‐ray diffraction. The crystal of 4 contains two similar independent molecules, 4a and 4b, for which was observed the migration of one OH hydrogen from ligand 1 to the OClO3 group, thus resulting in [Ag(HClO4)Se{OCCH2Me2}{(OH)CCH2Me2}], where ligand 1 behaves as an O,Se monometallic biconective moiety. In 5 the ligand 2 acts as a N,Se,N monometallic triconective moiety. In both compounds Ag(I) is surrounded by the donor atoms in a trigonal pyramidal coordination geometry. Strong Se→Ag intermolecular interactions in 4 resulted in 1D coordination polymers built by 4a and 4b molecules, respectively, while in the crystal of 5 no interaction between heavy atoms was observed. Supramolecular networks based on H‧‧‧O contacts are formed in both compounds.

Equation-of-Motion Coupled-Cluster Protocol for Calculating Magnetic Properties: Theory and Applications to Single-Molecule Magnets.

We present a new computational protocol for computing macroscopic magnetic properties of transition-metal complexes using the equation-of-motion coupled-cluster (EOM-CC) framework. The approach follows a two-step state-interaction scheme: we first compute zero-order states using nonrelativistic EOM-CC and then use these states to evaluate matrix elements of the spin-orbit and Zeeman operators. Diagonalization of the resulting Hamiltonian yields spin-orbit- and field-perturbed eigenstates. Temperature- and field-dependent magnetization and susceptibility are computed by numerical differentiation of the partition function. To compare with powder-sample experiments, these quantities are numerically averaged over field orientations. We applied this protocol to several single-molecule magnets (SMMs) with Fe(II) and Fe(III) in trigonal pyramidal, linear, and trigonal bipyramidal coordination environments. We described the underlying electronic structure by the electron-attachment (EOM-EA) and spin-flip (EOM-SF) variants of EOM-CC. The computed energy barriers for spin inversion, and macroscopic magnetization and susceptibility agree well with experimental data. Trends in magnetic anisotropy and spin-reversal energy barriers are explained in terms of a molecular orbital picture rigorously distilled from spinless transition density matrices between many-body states. The results illustrate excellent performances of EOM-CC in describing magnetic behavior of mononuclear transition-metal SMMs.

Copper(I) azide and copper(I) cyanate π-complexes

Electrochemical alternating current synthesis starting from an ethanol solution of CuSO4 · 5H2O and allylamine in the presence of solid sodium azide results in formation of Cu[C3H5NH2]N3. The trigonal-pyramidal coordination environment of both crystallographically independent copper ions consists of the C = C-bond of one allylamine molecule, the NH2-group of another ligand moiety and two N-atoms of the two azide-anions. One N3 − exhibits a terminal coordination mode and the other is a μ3-1,1,3-bridge. The bridging function of both allylamine and azide leads to formation of a complicated 3-D network. An elongation of coordinated C = C-bond and a strong shift of the ν s mode in the Raman spectrum confirm effective Cu–(C = C) bonding. A similar synthetic route starting from a methanol solution of Cu(BF4)2 · 6H2O in the presence of solid potassium cyanate results in formation of Cu[C3H5NH2]NCO. The cyanate-anion is bound to copper through nitrogen. The nitrogen from the allylamine molecule and the C = C-bond from another ligand complete the trigonal-planar environment of copper. The elongation of the coordinated C = C-bond and the shift of ν s (C = C) mode in the Raman spectrum are similar to those in the azide derivative.

Synthesis and crystal structure of copper(I) nitrate π-complex with 1-(4-methylphenyl)-5-allylsulfanyl-1H-tetrazole

By means of the alternating-current electrochemical technique a novel copper(I) π,σ-compound [Cu 2 ( Matht ) 2 (H 2 O) 2 ](NO 3 ) 2 ( 1 ) with 1-(4-methylphenyl)-5-allylsulfanyl-1 H -tetrazole ( Matht ) was obtained in a single crystal form and structurally characterized by single crystal X-ray diffraction. 1-(4-Methylphenyl)-5-allylsulfanyl-1 H -tetrazole was prepared in several stages by known protocol, starting from 4-methylaniline. Diffraction data for 1 were collected on a Rigaku AFC7 diffractometer using Mo K a radiation ( λ = 0.71069 Å). The collected diffraction data were processed using CrysAlis RED program. The structure was solved by SIR-92 and refined by least squares method on F 2 by ShelXL. π-Complexe crystallize in the acentric space group Pna 2 1 : a = 27.2002(7), b = 9.7219(3), c = 10.9773(3) Å, V = 2902.81(14) Å 3 , Z = 4. The organometallic component of the structure of complex 1 is represented by the dimer {Cu 2 ( Matht ) 2 (H 2 O) 2 } 2+ , which is formed by chelate-bridging coordination of two organic molecules Matht to Cu + ions. The Cu(I) ion assumes a close to trigonal-pyramidal coordination environment (2N, (C=C) + O), which includes the η 2 -allyl group, the two most nucleophilic N atoms of two adjacent tetrazole nuclei and a water molecule. The water O atom occupies the apical position of the copper(I) polyhedron. The corresponding geometric index τ 4 for copper(I) is 0.81 (for Cu1) and 0.79 (for Cu2). In the structure, despite the trans-arrangement of coordinated molecules relatively to the six-membered {Cu 2 N 4 } cycle, an acentric dimer {Cu 2 ( Matht ) 2 (H 2 O) 2 } 2+ with two independent copper(I) ions is formed. The asymmetry of the latter is associated with the arrangement of one of the allylic groups (atoms C31 and C32) in two positions with a S.O.F. = 0.5. The dihedral angle between the planes of tetrazole and aryl rings equals to 50.0 o . Water molecule plays a role of bridge among the cationic organometallic nucleus and nitrate anions, connecting them by means of hydrogen bonds O−H···O into H-bonded framework. Keywords: copper(I), π-complex, allyl tetrazole, crystal structure.

Cu(I) Arylsulfonate π-Complexes with 3-Allyl-2-thiohydantoin: The Role of the Weak Interactions in Structural Organization

The present work is directed toward preparation and structural characterization of two novel Cu(I) arylsulfonate π-complexes with 3-allyl-2-thiohydantoin, namely [Cu2(Hath)4](C6H5SO3)2 (1) and [Cu2(Hath)4](p-CH3C6H4SO3)2 · 2H2O (2) (Hath = 3-allyl-2-thiohydantoin), obtained by the means of alternating current electrochemical synthesis and studied with X-ray diffraction method. In both structures, the inner coordination sphere is represented by the cationic dimer [Cu2(Hath)4]2+ with one crystallographically independent copper(I) atom which has a trigonal pyramidal coordination environment formed by three Hath thiogroup S atoms and double C=C bond of its allyl group. [Cu2(Hath)4]2+ fragments in both coordination compounds are very similar, despite some divergences such as a big difference in Cu−S distance to the apical S atom (3.0374(8) Å in 1 and 2.7205(9) Å in 2). This difference was explained by the impact of the system of weak interactions, which are quite different.

Copper Clusters Containing Hydrides in Trigonal Pyramidal Geometry

Structurally precise copper hydrides [Cu11H2{S2P(OiPr)2}6(C≡CR)3], R = Ph (1), C6H4F (2), and C6H4OMe (3), were first synthesized from the polyhydrido copper cluster [Cu20H11{S2P(OiPr)2}9] with nine equivalents of terminal alkynes. Later, their isolated yields were significantly improved by direct synthesis from [Cu(CH3CN)4](PF6), [NH4][S2P(OiPr)2], NaBH4, and alkynes along with NEt3 in THF. 1, 2, and 3 were fully characterized by single-crystal X-ray diffraction, ESI-MS, and multinuclear NMR spectroscopy. All three clustershave 11 copper atoms, adopting 3,3,4,4,4-pentacapped trigonal prismatic geometry, with two hydrides inside the Cu11 cage, the position of which was ascertained by a single-crystal neutron diffraction structure of cluster 1 co-crystallized with a [Cu7(H){S2P(OiPr)2}6] (4) cluster. Six dithiophosphate and three alkynyl ligands stabilize the Cu11H2 core in which the two hydrides adopt a trigonal pyramidal coordination mode. This coordination mode is so far unprecedented for hydride. The 1H NMR resonance frequency of the two hydrides appears at 4.8 ppm, a value further confirmed by 2H NMR spectroscopy for their deuteride derivatives [Cu11(D)2{S2P(OiPr)2}6(C≡CR)3]. A DFT investigation allows understanding the bonding within this new type of copper(I) hydrides.

Synthesis and Crystallographic, Absorption and Emission Studies of 4-Pyridine Carboxamide of Zn(II) 4-Chlorophenylacetate.

A new zinc(II) complex, [Zn(CB)2(INA)2] (where CB is 4-chlorophenylacetate and INA is 4-pyridine carboxamide) was synthesized. The structure of the complex was characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction technique. Besides, the thermal stability of the complex was investigated by TGA/DTA analysis method. Moreover, the optical absorption and the emission features of the complex were examined by using UV-Vis and fluorescence spectrophotometers, respectively. Furthermore, Density Functional Theory (DFT) calculations were carried out to support the experimental results. Accordingly, it was determined that the complex crystallized in a monoclinic system with space group Pc, a = 8.3329 (2) Å, b = 25.6530 (4) Å, c = 13.5048 (3) Å, α = 90°, β = 91.703 (3)° and γ = 90°. The complex consists two crystallographically independent molecules. In each molecule, the ZnII ion adopts a distorted trigonal pyramidal coordination formed by two O atoms from the two 4 chlorophenylacetate ligand and two N atoms of the two 4-pyridine carboxamide ligands. It was observed that the linear absorption spectra of the complex were similar to linear absorption spectra of the semiconductors. In addition, two emission peaks were observed in the fluorescence spectra which could be due to the formation of excimer and the interactions of the benzene and pyridine rings. The energy gap (ΔEgap = ELUMO - EHOMO) of the complex has been calculated as 3.712eV and this value is very close to the experimentally measured value (3.86eV). Therefore, because of higher fluorescence intensity of emission peak that was observed between 309 and 556nm wavelength besides other traits, the complex could potentially be used in the blue light OLED application by filtering of the emission peak around 710nm wavelength. Graphical Abstract It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. The fluorescence measurements showed that these materials are much suitable for application area of the detection of nitroaromatic explosives. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results. It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results.

The oxidation state and coordination environment of antimony in silicate glasses

Antimony K-edge X-ray absorption near edge structure (XANES) spectra were recorded for Sb in glasses of five synthetic CaO-MgO-Al2O3-SiO2 (CMAS) compositions and a simplified mid-ocean ridge basalt (MORB). The glasses were quenched from melts equilibrated at 1300 °C, atmospheric pressure, and oxygen fugacities (fO2) from logfO2 = –9 to 0 (ΔQFM from −1.7 to 7.3, where ΔQFM is the fO2 in log units relative to the quartz-fayalite-magnetite buffer), and 1400 °C, 1.0 GPa and logfO2 = +4.7 (ΔQFM+11.0). Comparison with model compounds (Sb, Sb2O3, β-Sb2O4, MnSb2O4 and Zn7Sb2O12) indicates that the oxidation state of Sb changes from Sb3+ to Sb5+ over the range of fO2 investigated. Using the spectra of the most reduced and oxidised glasses as end-members the oxidation state of Sb, Sb5+/ΣSb (where ΣSb = Sb3+ + Sb5+), was determined from the spectra of other samples by linear combination fitting. At terrestrial fO2s nearly all Sb occurs as Sb3+ in these silicate melts. The stability of Sb5+ was found to be positively correlated with the CaO content and optical basicity of the melts. Extended X-ray absorption fine structure (EXAFS) spectra were recorded for glasses prepared at pressures from 1.0 to 3.0 GPa, for which Sb5+/ΣSb = 0 and 1, and for a synthetic Sb-bearing sample of anorthite. The Sb3+O and Sb5+O bond lengths in the glasses are similar (1.938(4) and 1.964(5) Å, respectively) and suggest trigonal pyramidal coordination of Sb3+and octahedral Sb5+. The Sb3+O bond length did not change with pressure. Anorthite (CaAl2Si2O8) was found to readily incorporate Sb as Sb5+ on a tetrahedral site.

Synthesis and crystal structure of mixed halide Cu(I) complexes with 1,3-benzimdazolone

By a direct reaction of 1,3-allylbenzimidazolone in ethanol medium with copper(II) halogenides under alternate current technique conditions with copper wire electrodes were obtained and X-ray single crystal method structurally characterized ( Agilent Gemini A diffractometer) three new isostructural pi-complexes of [C 7 H 4 N 2 O(C 3 H 5 ) 2 Cu 2 X 2 ] composition: space group , Z = 2, X= 0,77Cl/0,33Br ( I ) – a = 8.358(3), b = 9.683(3), c = 9.749(3) A, α = 85.04(3), β = 75.96(3), γ = 70.39(3)°, V = 721.1(4) A 3 , r calc. = 1.99 g/cm 3 , m( MoK a ) = 4.48 mm −1 , q max. = 36.8°, 9089 measured, 4927 used reflections, R ( F 2 ) = 0.057, S = 1.12; X= 0.25Cl/0,75Br ( II ) – a = 8.3294(8), b = 9.8050(11), c = 9.8368(5) A, α = 85.572(6), β = 76.528(6), γ = 70.931(9)°, V = 738.39(12) A 3 , r calc. = 2.16 g/cm 3 , m( CuK a ) = 9.10 mm −1 , q max. = 73.4°, 10408 measured, 2879 used reflections, R ( F 2 ) = 0.040, S = 1.03; X= Br ( III ) – a = 8.3086(3), b = 9.8417(3), c = 9.8642(4) A, α = 85.739(3), β = 76.780(3), γ = 71.049(3)°, V = 742.66(5) A 3 , r calc. = 2.24 g/cm 3 , m( MoK a ) = 8,24 mm −1 , q max. = 29.9°, 11904 measured, 3692 used reflections, R(F 2 ) = 0.020, S = 1.06. Structures were solved by direct methods and refined by full matrix least-squares method on F 2 by SHELXT and SHELXL-2014 with following graphical user interfaces of OLEX 2 . In a crystal structure of the compounds I–III two structurally independent copper atoms possesses trigonal-pyramidal coordination environment consisted of C=C bonds of both allylic groups of organic ligands and halide or oxygen atoms. Due to bridging function of halogenides anions metal coordination polyhedra connected into tetrameric topological units. Last due to coordination of allylic groups of 1,3-dyallylbenzimidazolone with crystallographically non equivalent copper(I) center metal coordination polyhedron linked to infinite chains {L 2 Cu 4 Х 4 } connected by very week C–H…Hal(O) bonds. Keywords : benzimidazolon, copper(І), pi-complexes, crystal structure.

Tris(2,6-dimethoxyphenyl)antimony Diazide: Synthesis and Structure

Tris(2,6-dimethoxyphenyl)antimony diazide has been synthesized and characterized by X-ray diffraction. The antimony atoms in four crystallographically independent molecules have a distorted trigonal pyramidal coordination. Axial angles range within 174.57°–178.95°.

Reactions of Tricymantrenylantimony with Halogens. Synthesis and Structure of Tricymantrenylantimony Dihydroxide

Tricymantrenylantimony dibromide [C5H4Mn(CO)3]3SbBr2 and dichloride [C5H4Mn(CO)3]3SbCl2 were synthesized by the reaction of tricymantrenylantimony with bromine and chlorine in chloroform; the products are transformed into tricymantrenylantimony dihydroxide [C5H4Mn(CO)3]3Sb(OH)2 by the action of potassium hydroxide in ethanol. Antimony atoms in the dihydroxide have a distorted trigonal–pyramidal coordination with oxygen atoms in axial positions [OSbO 175.66(8)°; Sb–O 1.987(2), 2.049(2), Sb–C 2.086(2), 2.101(2), and 2.105(2) A].

Efficient photocatalytic water reduction by a cobalt(ii) tripodal iminopyridine complex

Enhanced reactivity is observed in a cobalt tripodal iminopyridine WRC bearing a metal active site with a trigonal pyramidal coordination geometry.

Crystal structure and Hirshfeld surface analysis of hexa-kis-(μ-benzoato-κ2O:O')bis-(pyridine-3-carbo-nitrile-κN1)trizinc(II).

The asymmetric unit of the title complex, [Zn3(C7H5O2)6(C6H4N2)2], contains one half of the complex mol-ecule, i.e. one and a half ZnII cations, three benzoate (Bnz) and one pyridine-3-carbo-nitrile (Cpy) mol-ecule; the Bnz anions act as bidentate ligands through the carboxyl-ate O atoms, while the Cpy ligand acts as a monodentate N(pyridine)-bonding ligand. The complete centrosymmetric trinuclear complex thus comprises a linear array of three ZnII cations. The central ZnII cation shows an octa-hedral coordination and is bridged to each of the terminal ZnII cations by three Bnz anions. By additional coordination of the CPy ligand, the terminal ZnII cations adopt a trigonal-pyramidal coordination environment. In the crystal, the Bnz anions link to the Cpy N atoms via weak C-H⋯N hydrogen bonds, forming a two-dimensional network. C-H⋯π and π-π inter-actions [between the benzene and pyridine rings of adjacent mol-ecules with an inter-centroid distance of 3.850 (4) Å] help to consolidate a three-dimensional architecture. The Hirshfeld surface analysis confirms the role of H-atom contacts in establishing the packing.