The cubic structure of Li3As stabilized by substitution - Li8TtAs4 (Tt = Si, Ge) and Li14TtAs6 (Tt = Si, Ge, Sn) and their lithium ion conductivity

The new lithium arsenidotetrelates Li8SiAs4, Li8GeAs4, Li14SiAs6, Li14GeAs6 and Li14SnAs6 were synthesized via ball milling and structurally characterized by Rietveld analysis of X-ray powder diffraction data. The aliovalent substitution of lithium in hexagonal Li3As by introducing a tetravalent tetrel cation stabilizes cubic structures for Li8TtAs4 (Tt = Si, Ge) in the space group Pa3̄ and for the lithium richer compound Li14TtAs6 (Tt = Si, Ge, Sn) in the higher symmetrical space group Fm3̄m (no. 225). Thermal properties of the arsenidotetrelates were investigated via high temperature powder diffraction and differential thermal analysis revealing a decomposition process of the lithium richer arsenidotetrelate (Li14TtAs6 → Li8TtAs4 + 2Li3As) into the lithium poorer arsenidotetrelates and lithium arsenide at moderate temperatures. Impedance spectroscopy shows moderate to good lithium ion conductivity for the lithium arsenidotetrelates.

Synthesis and Characterization of Na4Si2Se6-tP24 and Na4Si2Se6-oP48, Two Polymorphs with Different Anionic Structures

Two different polymorphs of the new selenosilicate Na₄Si₂Se₆ were synthesized by solid-state reactions. The high-temperature polymorph Na₄Si₂Se₆-tP24 crystallizes in the tetragonal space group P4₂/mcm (No. 132) with lattice parameters a = 7.2793(2) Å, c = 12.4960(4) Å, and V = 662.14(3) ų. The main structural motifs are isolated Si₂Se₆ units of two edge-sharing SiSe₄ tetrahedra. The high-pressure/low-temperature polymorph Na₄Si₂Se₆-oP48 crystallizes in the orthorhombic space group Pbca (No. 61) with lattice parameters a = 12.9276(1) Å, b = 15.9324(1) Å, c = 6.0349(1) Å, and V = 1243.00(2) ų showing zweier single chains _∞¹[Si₂Se₆]^4-. The lattice parameters of Na₄Si₂Se₆-tP24 were determined by single-crystal X-ray diffraction, whereas those of Na₄Si₂Se₆-oP48 were investigated by powder X-ray diffraction. Both modifications crystallize in new structure types. An energetic comparison of the two polymorphs and further hypothetical structure types was carried out by density functional theory modeling. Calculations reveal that the polymorphs are very close in energy (ΔE = 3.4 kJ mol^-1). Impedance spectroscopic measurements show ionic conductivity (σ_spec = 1.4 × 10^-8 S cm^-1 at 50 °C and 6.8 × 10^-6 S cm^-1 at 200 °C) with an activation energy of E_A = 0.54(2) eV for Na₄Si₂Se₆-oP48.

Effect of antifluorite layer on the magnetic order in Eu-based 1111 compounds, EuTAsF (T = Zn, Mn, and Fe)

The 1111 compounds with an alternating sequence of fluorite and antifluorite layers serve as structural hosts for the vast family of Fe-based superconductors. Here, we use neutron powder diffraction and density-functional-theory (DFT) band-structure calculations to study magnetic order of Eu²⁺ in the [EuF]⁺ fluorite layers depending on the nature of the [TAs]^- antifluorite layer that can be non-magnetic semiconducting (T = Zn), magnetic semiconducting (T = Mn), or magnetic metallic (T = Fe). Antiferromagnetic transitions at T_N ∼ 2.4-3 K due to an ordering of the Eu²⁺ magnetic moments were confirmed in all three EuTAsF compounds. Whereas in EuTAsF (T = Zn and Mn), the commensurate k₁ = (½ ½ 0) stripe order pattern with magnetic moments within the a-b plane is observed, the order in EuFeAsF is incommensurate with k = (0 0.961(1) ½) and represents a cycloid of Eu²⁺ magnetic moments confined within the bc-plane. Additionally, the Mn²⁺ sublattice in EuMnAsF features a robust G-type antiferromagnetic order that persists at least up to room temperature, with magnetic moments along the c-direction. Although DFT calculations suggest stripe antiferromagnetic order in the Fe-sublattice of EuFeAsF as the ground state, neutron diffraction reveals no evidence of long-range magnetic order associated with Fe. We show that the frustrating interplane interaction J₃ between the adjacent [EuF]⁺ layers is comparable with in-plane J₁-J₂ interactions already in the case of semiconducting fluorite layers [TAs]^- (T = Zn and Mn) and becomes dominant in the case of the metallic [FeAs]^- ones. The latter, along with a slight orthorhombic distortion, is proposed to be the origin of the incommensurate magnetic structure observed in EuFeAsF.

Testing of Exchange-Correlation Functionals of DFT for a Reliable Description of the Electron Density Distribution in Organic Molecules

Researchers carrying out calculations using the DFT method face the problem of the correct choice of the exchange-correlation functional to describe the quantities they are interested in. This article deals with benchmark calculations aimed at testing various exchange-correlation functionals in terms of a reliable description of the electron density distribution in molecules. For this purpose, 30 functionals representing all rungs of Jacob's Ladder are selected and then the values of some QTAIM-based parameters are compared with their reference equivalents obtained at the CCSD/aug-cc-pVTZ level of theory. The presented results show that the DFT method undoubtedly has the greatest problems with a reliable description of the electron density distribution in multiple strongly polar bonds, such as C=O, and bonds associated with large electron charge delocalization. The performance of the tested functionals turned out to be unsystematic. Nevertheless, in terms of a reliable general description of QTAIM-based parameters, the M11, SVWN, BHHLYP, M06-HF, and, to a slightly lesser extent, also BLYP, B3LYP, and X3LYP functionals turned out to be the worst. It is alarming to find the most popular B3LYP functional in this group. On the other hand, in the case of the electron density at the bond critical point, being the most important QTAIM-based parameter, the M06-HF functional is especially discouraged due to the very poor description of the C=O bond. On the contrary, the VSXC, M06-L, SOGGA11-X, M06-2X, MN12-SX, and, to a slightly lesser extent, also TPSS, TPSSh, and B1B95 perform well in this respect. Particularly noteworthy is the overwhelming performance of double hybrids in terms of reliable values of bond delocalization indices. The results show that there is no clear improvement in the reliability of describing the electron density distribution with climbing Jacob's Ladder, as top-ranked double hybrids are also, in some cases, able to produce poor values compared to CCSD.

The specific features of phononic and magnetic subsystems of type-VII clathrate EuNi2P4

A type-VII clathrate with a Eu2+ guest embedded into a Ni-P covalent framework, EuNi2P4, was synthesized by a standard two-stage ampoule synthesis and confirmed to crystallize in the orthorhombic space group Fddd with unit cell parameters a = 5.1829(1) Å, b = 9.4765(1) Å, and c = 18.9900(1) Å. A general technique for studying the lattice and magnetic properties of REE containing compounds is proposed. The temperature and field dependences of electrical resistivity ρ(T,H), magnetization M(T,H), magnetic susceptibility χ(T,H), heat capacity Cp(T), and unit cell parameters a(T), b(T), c(T), and volume V(T) were experimentally studied and analyzed at different pressures in the temperature range of 2-300 K. A cascade of anomalies in the studied dependences was identified and attributed to the magnetic phase transformation and peculiar lattice contributions at temperatures below 20 K. As a result of comparison with an isostructural clathrate SrNi2P4, the parameters of the magnetic and lattice contributions were determined. It is characteristic that the phase transition from the paramagnetic to the magnetically ordered state is not reflected in the temperature changes of the lattice parameters due to weak bonds between guest europium atoms and the Ni-P host matrix. We have constructed a tentative H-T phase diagram based on the M(T) and M(H) data, which includes 6 different phases. It is established that the anomalous lattice contribution to the clathrate heat capacity CTLS(T) appears due to the effect of two-level systems (TLS) in the Eu2+ subsystem on the thermodynamic properties of EuNi2P4. The values of TLS parameters as well as the parameters of the magnetic subsystem of the clathrate were determined.

Synthesis, electronic structure and physical properties of two new layered compounds, EuFAgSe and EuFAg1-δTe, featuring the active redox pair Eu2+/Ag. Dalton Trans 2020;49:7426-7435. [PMID: 32432284 DOI: 10.1039/d0dt01504k]

Systematic studies of the ZrCuSiAs (also LaOAgS or 1111) structure type resulted in the synthesis of two new fluoride chalcogenides, EuFAgSe and EuFAg1-δTe, whereas their sulfide analog, EuFAgS, could not be obtained. Both new compounds are tetragonal, P4/nmm, with cell parameters a = 4.1542(1) Å, c = 9.2182(1) Å for the selenide and a = 4.3255(1) Å, c = 9.5486(1) Å for the telluride. Rietveld refinement reveals a significant silver deficiency in the telluride (δ = 0.05), while the selenide is nearly stoichiometric. Both compounds are semiconductors as shown by diffuse reflectance spectroscopy and confirmed by density-functional calculations of the band structure. Magnetism of both compounds is predominantly driven by Eu2+, as indicated by magnetic susceptibility measurements and corroborated by 151Eu Mössbauer spectroscopy. EuFAg1-δTe and EuFAgSe are paramagnetic down to 1.8 K.

Influence of the epitaxial composition on N-face GaN KOH etch kinetics determined by ICP-OES

Roughening by anisotropic etching of N-face gallium nitride is the key aspect in today's production of blue and white light emitting diodes (LEDs). Both surface area and number of surface angles are increased, facilitating light outcoupling from the LED chip. The structure of a GaN layer stack grown by metal organic chemical vapour deposition (MOCVD) was varied in the unintentionally doped u-GaN bulk region. Different sequences of 2D and 3D grown layers led to a variation in dislocation density, which was monitored by photoluminescence microscopy (PLM) and X-ray diffraction (XRD). Thin-film processing including laser lift off (LLO) was applied. The influence of epitaxial changes on the N-face etch kinetics was determined in aqueous KOH solution at elevated temperature. Inductively-coupled plasma optical emission spectroscopy (ICP-OES) was used to measure the etch progress in small time increments with high precision. Thereby, the disadvantages of other techniques such as determination of weight loss or height difference were overcome, achieving high accuracy and reproducibility.

EuNi2P4, the first magnetic unconventional clathrate prepared via a mechanochemically assisted route

The first magnetic unconventional clathrate EuNi₂P₄ has been prepared and its thermodynamic properties have been investigated.

Synthesis, crystal and electronic structures of Pt-rich phosphides EuPt3P and EuPt6P2

Two new ternary Pt-rich phosphides, EuPt6P2 and EuPt3P, have been prepared via a two-step solid state reaction. Their crystal structures have been determined from powder XRD data. EuPt6P2 is isostructural to SrPt6P2 (cubic, Pa3[combining macron], a = 8.4603(1) Å); its crystal structure comprises corner-sharing Pt6P trigonal prisms hosting Eu2+ cations in the cuboctahedral voids of the framework. EuPt3P is isostructural to the SrPt3P anti-perovskite (P4/nmm, a = 5.7452(1) Å and c = 5.4212(1) Å). Magnetization measurements reveal the magnetic response caused by the Eu2+(4f7) cations. EuPt6P2 is paramagnetic exhibiting no phase transitions down to 1.8 K, whereas EuPt3P orders ferromagnetically below 19 K. Similar to SrPt6P2 and SrPt3P, the new compounds are metallic with states near the Fermi level predominantly formed by the 5d orbitals of Pt.

Self-Assembly of Short Chain Poly- N-isopropylacrylamid Induced by Superchaotropic Keggin Polyoxometalates: From Globules to Sheets

We show here for the first time that short chain poly( N-isopropylacrylamide) (PNIPAM), one of the most famous thermoresponsive polymers, self-assembles in water to form (i) discrete nanometer-globules and (ii) micrometric sheets with nm-thickness upon addition of the well-known Keggin-type polyoxometalate (POM) H₃PW₁₂O₄₀ (PW). The type of self-assembly is controlled by PW concentration: at low PW concentrations, PW adsorbs on PNIPAM chains to form globules consisting of homogeneously distributed PWs in PNIPAM droplets of several nm in size. Upon further addition of PW, a phase transition from globules to micrometric sheets is observed for PNIPAMs above a polymer critical chain length, between 18 and 44 repeating units. The thickness of the sheets is controlled by the PNIPAM chain length, here from 44 to 88 repeating units. The PNIPAM sheets are electrostatically stabilized PWs accumulated on each side of the sheets. The shortest PNIPAM chain with 18 repeating units produces PNIPAM/PW globules with 5-20 nm size but no sheets. The PW/PNIPAM self-assembly arises from a solvent mediated mechanism associated with the partial dehydration of PW and of the PNIPAM, which is related to the general propensity of POMs to adsorb on neutral hydrated surfaces. This effect, known as superchaotropy, is further highlighted by the significant increase in the lower critical solubilization temperature (LCST) of PNIPAM observed upon the addition of PW in the mM range. The influence of the POM nature on the self-assembly of PNIPAM was also investigated by using H₄SiW₁₂O₄₀ (SiW) and H₃PMo₁₂O₄₀ (PMo), i.e. changing the POM's charge density or polarizability in order to get deeper understanding on the role of electrostatics and polarizability in the PNIPAM self-assembly process. We show here that the superchaotropic behavior of POMs with PNIPAM polymers enables the formation and the shape control of supramolecular organic-inorganic hybrids.

Layered Compounds BaFMgPn (Pn = P, As, Sb, and Bi), Transition-Metal-Free Representatives of the 1111 Structure Type

Four new transition metal-free pnictide representatives of the LaOAgS structure type were predicted by DFT calculations and found in the BaFMgPn (Pn = P, As, Sb and Bi) family. The compounds adopt the tetragonal space group P4 /nmm with the unit cell parameters a/ c 4.3097(1) Å/9.5032(1) Å, 4.3855(1) Å/9.5918(1) Å, 4.5733(1) Å/9.8184(1) Å, and 4.6359(1) Å/9.8599(1) Å, respectively. According to the DFT calculations, these new compounds are semiconductors with band gaps steadily decreasing from Pn = P ( ca. 2 eV) to Pn = Bi ( ca. 1 eV). The corresponding strontium fluoride and rare-earth oxide analogs are unlikely to exist and have not been observed yet. The trends of the stability within 1111 and structurally and/or chemically related compounds based on a combined consideration of geometry and DFT calculations are discussed.

Ab initio prediction of structuring/mesoscale inhomogeneities in surfactant-free microemulsions and hydrogen-bonding-free microemulsions

Prediction of microemulsion-like structuring in surfactant-free and hydrogen-bonding-free systems.

In Situ X-ray Diffraction Study of the Thermal Decomposition of Selenogallates Cs2[Ga2(Se2)2- xSe2+ x] ( x = 0, 1, 2)

The selenogallates CsGaSe₃ and Cs₂Ga₂Se₅ release gaseous selenium upon heating. An in situ high-temperature X-ray powder diffraction analysis revealed a two-step degradation process from CsGaSe₃ to Cs₂Ga₂Se₅ and finally to CsGaSe₂. During each step, one Se₂^2- unit of the anionic chains in Cs₂[Ga₂(Se₂)_{2- x}Se_{2+ x}] ( x = 0, 1, 2) decomposes, and one equivalent of selenium is released. This thermal decomposition can be reverted by simple addition of elemental selenium and subsequent annealing of the samples below the decomposition temperature. The influence of the diselenide units in the anionic selenogallate chains on the optical properties and electronic structures was further studied by UV/vis diffuse reflectance spectroscopy and relativistic density functional theory calculations, revealing increasing optical band gaps with decreasing Se₂^2- content.

Influence of ancillary ligands on the photophysical properties of cyclometalated organoplatinum(ii) complexes

The photophysical properties of three series of cyclometalated organoplatinum(ii) complexes were studied and the influence of changing the ancillary ligands and substituents on their luminescence properties were investigated.

Polyoxometalates in the Hofmeister series

We propose a simple experimental procedure based on the cloud point measurement of a non-ionic surfactant as a tool for (i) estimating the super-chaotropic behaviour of polyoxometalates (POMs) and for (ii) establishing a classification of POMs according to their affinity towards polar surfaces.

Polymorphism of CsGaS2– structural characterization of a new two-dimensional polymorph and study of the phase-transition kinetics

Anionic layers in CsGaS₂undergo a transition to infinite strands at high temperature and transfer back under pressure.

The impact of the structuring of hydrotropes in water on the mesoscale solubilisation of a third hydrophobic component

The complex structuring of alcohols in water influences the mesoscale solubilisation of a third component depending on its nature.

A systematic study of the influence of mesoscale structuring on the kinetics of a chemical reaction

In this contribution, we link the mesoscopic structuring of the binary structured solvent mixture H₂O/tert-butanol (TBA) to the kinetics and efficacy of the oxidation of benzyl alcohol (BA) to the corresponding aldehyde catalyzed by H₅PMo₁₀V₂O₄₀.

Phosphorescent heterobimetallic complexes involving platinum(iv) and rhenium(vii) centers connected by an unsupported μ-oxido bridge

Heterobimetallic compounds containing an unsupported Pt(iv)–O–Re(vii) bridge are synthesized. The complexes exhibit rare phosphorescence emission in solid and frozen states.

Na2TeS3, Na2TeSe3-mP24, and Na2TeSe3-mC48: Crystal Structures and Optical and Electrical Properties of Sodium Chalcogenidotellurates(IV)

Pure samples of Na2TeS3 and Na2TeSe3 were synthesized by the reactions of stoichiometric amounts of the elements Na, Te, and Q (Q = S, Se) in the ratio 2:1:3. Both compounds are highly air- and moisture-sensitive. The crystal structures were determined by single-crystal X-ray diffraction. Yellow Na2TeS3 crystallizes in the space group P21/c. Na2TeSe3 exists in a low-temperature modification (Na2TeSe3-mP24, space group P21/c) and a high-temperature modification (Na2TeSe3-mC48, space group C2/c); both modifications are red. Density functional theory calculations confirmed the coexistence of both modifications of Na2TeSe3 because they are very close in energy (ΔE = 0.18 kJ mol(-1)). To the contrary, hypothetic Na2TeS3-mC48 is significantly less favored (ΔE = 1.8 kJ mol(-1)) than the primitive modification. Na2TeS3 and Na2TeSe3-mP24 are isotypic to Li2TeS3, whereas Na2TeSe3-mC48 crystallizes in its own structure type, which was first described by Eisenmann and Zagler. The title compounds have two common structure motifs. Trigonal TeQ3 pyramids form layers, and the Na atoms are surrounded by a distorted octahedral environment of chalcogen atoms. Raman spectra are dominated by the vibration modes of the TeQ3 units. The activation energies of the total conductivity of the title compounds range between 0.68 eV (Na2TeS3) and 1.1 eV (Na2TeSe3). Direct principal band gaps of 1.20 and 1.72 eV were calculated for Na2TeSe3 and Na2TeS3, respectively. The optical band gaps are in the range from 1.38 eV for Li2TeSe3 to 2.35 eV for Na2TeS3.

Li17Sb13S28: A New Lithium Ion Conductor and addition to the Phase Diagram Li2S-Sb2S3

Li17Sb13S28 was synthesized by solid-state reaction of stoichiometric amounts of anhydrous Li2S and Sb2S3. The crystal structure of Li17Sb13S28 was determined from dark-red single crystals at room temperature. The title compound crystallizes in the monoclinic space group C2/m (no. 12) with a=12.765(2) Å, b=11.6195(8) Å, c=9.2564(9) Å, β=119.665(6)°, V=1193.0(2) Å(3), and Z=4 (data at 20 °C, lattice constants from powder diffraction). The crystal structure contains one cation site with a mixed occupation by Li and Sb, and one with an antimony split position. Antimony and sulfur form slightly distorted tetragonal bipyramidal [SbS5E] units (E=free electron pair). Six of these units are arranged around a vacancy in the anion substructure. The lone electron pairs E of the antimony(III) cations are arranged around these vacancies. Thus, a variant of the rock salt structure type with ordered vacancies in the anionic substructure results. Impedance spectroscopic measurements of Li17Sb13S28 show a specific conductivity of 2.9×10(-9) Ω(-1) cm(-1) at 323 K and of 7.9×10(-6) Ω(-1) cm(-1) at 563 K, the corresponding activation energy is EA=0.4 eV below 403 K and EA=0.6 eV above. Raman spectra are dominated by the Sb-S stretching modes of the [SbS5] units at 315 and 341 cm(-1) at room temperature. Differential thermal analysis (DTA) measurements of Li17Sb13S28 indicate peritectic melting at 854 K.

trans-Platinum(II) complex of 3-aminoflavone - synthesis, X-ray crystal structure and biological activities in vitro

This paper describes the synthesis of trans-bis-(3-aminoflavone)dichloridoplatinum(ii) (trans-Pt(3-af)2Cl2; TCAP) for use as a potential anticancer compound, and the evaluation of its structure by elemental and spectral analyses, and X-ray crystallography. The complex demonstrated a significant cytotoxic effect against human and murine cancer cell lines, as well as weaker toxicity towards healthy cells (human peripheral blood lymphocytes) in comparison with cisplatin. Various biochemical and morphological methods confirm that the proapoptotic activity of trans-Pt(3-af)2Cl2 is markedly higher than the reference cisplatin. Our results suggest that trans-Pt(3-af)2Cl2 may have a different antitumour specificity from that of cisplatin.

Halocuprate(i) zigzag chain structures with N-methylated DABCO cations – bright metal-centered luminescence and thermally activated color shifts

Two halocuprate(i) chain structures were synthesized and studied with respect to their emission properties that are governed by two interacting chain segments.

[Aortic thrombosis in a calf]

A two month-old female Simmental calf was presented with sensomotoric dysfunction and recumbency. Neurologic examination revealed dysfunction of the cerebral cortex and paralysis of both hind limbs. Examination of the skeletal system revealed a marked reduction of the skin temperature of both hind limbs and the absence of femoral pulse. Examination of cerebrospinal fluid yielded physiological parameters. The radiographic examination of the vertebral column, hip and femur on both sides revealed no evidence of alteration of the bone structures. Thiamine pyrophosphate test indicated thiamine deficiency. Based on these findings a tentative diagnosis of cerebrocortical necrosis and aortic thrombosis were made and the animal was euthanised. Post mortem examination yielded thrombosis of the abdominal aorta cranial to the branching of the iliac arteries and consecutive necrosis of the skeletal muscle of the hind limbs. Possible causes of pathogenesis are discussed.

Li2ZnI4, das erste Iodid mit Olivinstruktur / Li2ZnI4, the First Olivine Type Iodide

In the system LiI — ZnI2, the hitherto unknown peritectically melting Li2ZnI4 has been established. It crystallizes in the olivine structure (a = 1480.3(9), b = 856.0(2), and c = 701.2(1) pm) and exhibits high ionic conductivity. Thermoanalytical and Raman spectroscopic data are included.

Tetrazinn(II)-und Bariumtrizinn(II)-tetrakis[μ3 -tri-ter/-butyIsilylphosphan- diid]-Verbindungen mit einem Tetrametallatetraphosphacuban-Gerüst / Tetratin(II) and Barium Tritin(II) Tetrakis[μ3-tri-rm-butylsilylphosphandiide] Compounds with a Tetrametallatetraphosphacubane Core

The metalation of tri-terr-butylsilylphosphane with bis[bis(trimethylsilyl)amino]stannylen yields nearly quantitatively the tetrameric tin(II) tri-terf-butylsilylphosphandiide with a central Sn4P4 cubane moiety. Barium bis[tri-tert-butylsilylphosphanide] is accessible via the reaction of tri-tert-butylsilylphosphane with barium bis[bis(trimethylsilyl)amide] in the molar ratio 2 : 1 . This phosphanide reacts with bis[bis(trimethylsilyl)amino]stannylen to give barium tritin(II) tetrakis[μ3-tri-tert-butylsilylphosphandiide]. Crystallographic data of 1: P 212121, T = 193 K, a = 1532.6(3), b = 2120.2(4), c = 2194.0(5) pm, V = 7.129(3) nm3, Z = 4, R, = 0.0360 (9132 observed data [I > 2a( f) ] ) , wR2 = 0.1064 (all data); crystallographic data of 3: P 21/c, T = 193 K, a = 1927.35(1), b = 1799.27(2), c = 2201.35(2) pm, β = 93.010(1)°, V = 7.6234(1) nm3, Z = 4, R1 = 0.0321 (11993 observed data [I > 2σ(/)]), wR2 = 0.0772 (all data).

Zinc Bis[μ-N,N′-chlorozinc-bis(N-trimethylsilylimino- diphenylphosphoranyl)- methanediide]: A Zinc Derivative of a Geminal Carbdianion

The trinuclear title compound, C74H88Cl2N4P4- Si4Zn3, is derived from a geminally substituted carbdianion. The central zinc atom shows a nearly linear coordination geometry with very short Zn- C bond lengths (average 191 pm). The peripheral metal centers of the chlorozinc moieties are chelated by the phosphanimine donors and hence are triply coordinated, thus forming a six-membered CP2N2Zn ring with Zn-N distances of 195 pm (average).

Kristallstruktur und Schwingungsspektren von Li5CrCl8 / Crystal Structure and Vibrational Spectra of Li5CrCl8

The crystal structure of the novel pink Li5CrCl8 oC28 has been determined by both single crystal X-ray and neutron powder studies. The title compound crystallizes in a hitherto unknown structure type (space group C mmm, Z = 2). The final R values are R = 3.4% (715 independent reflections with I > 3aI) and Rwp = 11.5%, respectively (a = 1019.79(3), b = 723.94(2) and c = 726.16(3) pm). The structure consists of edge-connected Li(l)Cl6 and alternating edge-connected Li(2)Cl6 and CrCl6 octahedra, respectively. It is related to the NaCl super structure SnMn2S4 type. IR and Raman spectra as well as symmetry coordinates are given and discussed in terms of CrCl6 and LiCl6 breathing modes.