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The crystal structure of the refractory ternary nitride ScTaN2 comprises alternating layers of ScN6/3 octahedra and trigonal TaN6/3 prisms. It can be described as an intergrowth structure of the binary nitrides delta-ScN and theta-TaN.

Research has been conducted on the crystal structure of Li (sub)7[Mn (super)V N (sub)4]. Results indicate that the isolated tetrahedral ions are arranged with the lithium cations forming the superstructure of the CaF (sub)2 anti-type.

The synthesis and characterization of the new ternary boron compound of magnesium and rhodium with the [Y.sub.2]Re[B.sub.6]-like crystal structure is reported.

Type-I clathrates Rb8-x-tKx...tAuyGe46-y are synthesized from Rb4G9, K4Ge9 Au, and Ge. Crystal structures and compositions are determined by single-crystal and powder X-ray diffraction methods. The lattice parameters are 10.8103(2), 10.7956(2), 10.7850(2), and 10.7723(2) A in space group Pm3n for Rb7.88(2) Rb3.69(4)K4.31(4)Au2.l7(2)Ge43.83(2) Rb1.66(S)K6.34(S)Au2.17(I)Ge43.831 )» ana K671(4Au2.28(2)Ge43.72(2)1 respectively. Bonding analysis for Rb8A6Ge40 suggests ionic interaction of Rb with the framework besides covalent interactions between Ge and Au/ Ge. Rb7 88Au2.47Ge43 S3 and K7,(4yAu12gGe4372 are both diamagnetic. The heat capacity of K6.71Au2.28KGe43.53 is analyzed. Transport properties of Rb7.88Au2.47Ge43.72(2)reveal n-type conducting, and low thermal conductivity. [ABSTRACT FROM AUTHOR]

Magnetic interactions in combination with nontrivial band structures can give rise to several exotic physical properties such as a large anomalous Hall effect, the anomalous Nernst effect, and the topological Hall effect (THE). Antiferromagnetic (AFM) materials exhibit the THE due to the presence of nontrivial spin structures. EuCuAs crystallizes in a hexagonal structure with an AFM ground state (Néel temperature ∼ 16 K). In this work, we observe a large topological Hall resistivity of ∼7.4 μΩ-cm at 13 K which is significantly higher than the giant topological Hall effect of Gd 2 PdSi 3 (∼3 μΩ-cm). Neutron diffraction experiments reveal that the spins form a transverse conical structure during the metamagnetic transition, resulting in the large THE. In addition, by controlling the magnetic ordering structure of EuCuAs with an external magnetic field, several fascinating topological states such as Dirac and Weyl semimetals have been revealed. These results suggest the possibility of spintronic devices based on antiferromagnets with tailored noncoplanar spin configurations.

Electrons in solids often adopt complex patterns of chemical bonding driven by the competition between energy gains from covalency and delocalization, and energy costs of double occupation to satisfy Pauli exclusion, with multiple intermediate states in the transition between highly localized, and magnetic, and delocalized, and nonmagnetic limits. Herein, we report a chemical pressure-driven transition from a proper Mn magnetic ordering phase transition to a Mn magnetic phase crossover in EuMn 2 P 2 the limiting end member of the EuMn 2 X 2 (X = Sb, As, P) family of layered materials. This loss of a magnetic ordering occurs despite EuMn 2 P 2 remaining an insulator at all temperatures, and with a phase transition to long-range Eu antiferromagnetic order at T N ≈ 17 K. The absence of a Mn magnetic phase transition contrasts with the formation of long-range Mn order at T ≈ 130 K in isoelectronic EuMn 2 Sb 2 and EuMn 2 As 2 . Temperature-dependent specific heat and 31 P NMR measurements provide evidence for the development of short-range Mn magnetic correlations from T ≈ 250-100 K, interpreted as a precursor to covalent bond formation. Density functional theory calculations demonstrate an unusual sensitivity of the band structure to the details of the imposed Mn and Eu magnetic order, with an antiferromagnetic Mn arrangement required to recapitulate an insulating state. Our results imply a picture in which long-range Mn magnetic order is suppressed by chemical pressure, but that antiferromagnetic correlations persist, narrowing bands and producing an insulating state.

Pure-phase cobalt-doped calcium hydroxyapatite ceramic samples with composition Ca 10 (PO 4 ) 6 [(CoO 2 ) x (OH) 1-2x ] 2 , where x = 0-0.2, were synthesized by high-temperature solid-state reaction, and their crystal structures, vibrational spectra, and magnetic properties were studied. Co atoms are found to enter into the apatite trigonal channel formally substituting H atoms and forming bent dioxocobaltate(II) anions. The anion exhibits single-molecule-magnet (SMM) behavior: slow relaxation of magnetization below 8 K under a nonzero magnetic field with an energy barrier of 63 cm -1 . The barrier value does not depend on the concentration of Co ions, virtually coincides with the zero-field-splitting energy as determined from direct-current magnetization, and is very close to the value obtained earlier for cobalt-doped strontium hydroxyapatite. Moreover, the vibration frequencies of the dioxocobaltate(II) anion are found to be the same in calcium and strontium apatite matrixes. The very weak dependence of the SMM parameters on the matrix nature in combination with good chemical and thermal stabilities of the compounds provides wide opportunities to exploit the intrinsic properties of such a SMM-like anion.

The title compound was synthesized by a reaction of the elemental educts in a corundum crucible at 1200 °C under an Ar atmosphere. The excess of Ga used in the initial mixture served as a flux for the subsequent crystal growth at 600 °C. The crystal structure of Yb 4 Ga 24 Pt 9 was determined from single-crystal X-ray diffraction data: new prototype of crystal structure, space group C2/m, Pearson symbol mS74, a = 7.4809(1) Å, b = 12.9546(2) Å, c = 13.2479(2) Å, β = 100.879(1)°, V = 1260.82(6) Å 3 , R F = 0.039 for 1781 observed reflections and 107 variable parameters. The structure is described as an ABABB stacking of two slabs with trigonal symmetry and compositions Yb 4 Ga 6 (A) and Ga 12 Pt 6 (B). The hard X-ray photoelectron spectrum (HAXPES) of Yb 4 Ga 24 Pt 9 shows both Yb 2+ and Yb 3+ contributions as evidence of an intermediate valence state of ytterbium. The evaluated Yb valence of ∼2.5 is in good agreement with the results obtained from the magnetic susceptibility measurements. The compound is a bad metallic conductor.

Single-ion magnets (SIMs) that can maintain magnetization direction on an individual transition metal atom represent the smallest atomic-scale units for future magnetic data storage devices and molecular electronics. Here we present a robust extended inorganic solid hosting efficient SIM centers, as an alternative to molecular SIM crystals. We show that unique dioxocobaltate(II) ions, confined in the channels of strontium hydroxyapatite, exhibit classical SIM features with a large energy barrier for magnetization reversal (U eff ) of 51-59 cm -1 . The samples have been tuned such that a magnetization hysteresis opens below 8 K and U eff increases by a factor of 4 and can be further enhanced to the highest values among 3d metal complexes of 275 cm -1 when Ba is substituted for Sr. The SIM properties are preserved without any tendency toward spin ordering up to a high Co concentration. At a maximal Co content, a hypothetical regular hexagonal grid of SIMs with a 1 nm interspacing on the (001) crystal facet would allow a maximal magnetic recording density of 10 5 Gb/cm 2 .

Reacting Cs 2 O 1.3 , TiTe, TiO 2 , and Te under inert conditions gives powders of Cs 1-x Ti 2 Te 2 O (x ≈ 0.2). Small single crystals of the same phase were obtained from a CsCl salt melt in closed ampoules. This cesium dititanium ditelluride oxide (P4/mmm, a = 4.0934(3) Å, c = 8.9504(9) Å) is isostructural to CeCr 2 Si 2 C and contains layers of face-sharing trans-TiTe 4 O 2 octahedra that are separated by Cs. As Ti occupies only one crystallographic site, its average oxidation state is +2.6, for the Cs deficit x = 0.2. The formally intermediate Ti valence state agrees well with the metallic conductivity and temperature-independent paramagnetic behavior. No superconductivity is observed down to 0.1 K in Cs 0.8 Ti 2 Te 2 O, but the fact that this structure type can accommodate Te 2- suggests that electron doping of structurally closely related pnictide oxide superconductors, for example, BaTi 2 Bi 2 O, might be possible.

The new osmates(VI), Sr2OsO5 and Sr7Os4O19, feature quasi-1-D polyoxo anions, consisting of corner sharing [OsO6] octahedra. In both compounds, the magnetic moment at T = 300 K is significantly lower (1.2-1.3 μB/Os-atom) than the value expected for S = 1. For neither of the new osmates(VI) is any evidence for long-range magnetic order found. For Sr7Os4O19, magnetic susceptibility suggests an antiferromagnetic ordering at TN = 43(3) K; however, no corresponding anomaly is visible in specific heat. Both compounds are semiconductors.

We report the high-pressure high-temperature synthesis (P = 15 GPa, T = 1300 K) of BaGe3(tI32) adopting a CaGe3-type crystal structure. Bonding analysis reveals layers of covalently bonded germanium dumbbells being involved in multicenter Ba-Ge interactions. Physical measurements evidence metal-type electrical conductivity and a transition to a superconducting state at 6.5 K. Chemical bonding and physical properties of the new modification are discussed in comparison to the earlier described hexagonal form BaGe3(hP8) with a columnar arrangement of Ge3 triangles.

ThPt2 crystallizes with unique type of structure (space group I4/mmm, a = 4.1565(1) Å, c = 14.3663(7) Å, Pearson symbol tI12), which belongs to the group of the close packed tetragonal structures. An analysis of the chemical bonding by the electron localizability approach reveals the formation of two-dimensional layered platinum anionic substructures interlinked by strongly polar bonds to Th. Measurements of magnetic susceptibility, electrical resistivity, and specific heat show ThPt2 to be diamagnetic with metallic type of electrical conductivity in good agreement with the calculated electronic structure (N(EF) = 0.9 states eV(-1) f.u.(-1)).

We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe6 (P = 15 GPa, T = 1073 K) and BaGe(6-x) (P = 10 GPa, T = 1073 K) which are metastable at ambient conditions. In BaGe(6-x), partial fragmentation of the BaGe6 network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe(6-x) is associated with the establishment of free electron pairs around the defects. In accordance with the electron precise composition of BaGe(6-x) for x = 0.5, physical measurements evidence semiconducting electron transport properties which are combined with low thermal conductivity.

Two new ternary arsenides, namely, Eu7Cu44As23 and Sr7Cu44As23, were synthesized from elements at 800 °C. Their crystal structure represents a new filled version of the BaHg11 motif with cubic voids alternately occupied by Eu(Sr) and As atoms, resulting in a 2 × 2 × 2 superstructure of the aristotype: space group Fm3̅m, a = 16.6707(2) Å and 16.7467(2) Å, respectively. The Eu derivative exhibits ferromagnetic ordering below 17.5 K. In agreement with band structure calculations both compounds are metals, exhibiting relatively low thermopower, but high electrical and low thermal conductivity.

Two atomic arrangements were found near the equiatomic composition in the strontium-lithium-arsenic system. Orthorhombic o-SrLiAs was synthesized by reaction of elemental components at 950 °C, followed by annealing at 800 °C and subsequent quenching in water. The hexagonal modification h-SrLi(1-x)As was obtained from annealing of o-SrLiAs at 550 °C in dynamic vacuum. The structures of both phases were determined by single-crystal X-ray diffraction: o-SrLiAs, structure type TiNiSi, space group Pnma, Pearson symbol oP12, a = 7.6458(2) Å, b = 4.5158(1) Å, c = 8.0403(3) Å, V = 277.61(2) Å(3), R(F) = 0.028 for 558 reflections; h-SrLi(1-x)As, structure type ZrBeSi, space group P6(3)/mmc, Pearson symbol hP6, a = 4.49277(9) Å, c = 8.0970(3) Å, V = 141.54(1) Å(3), RF = 0.026 for 113 reflections. The analysis of the electron density within the framework of the quantum theory of atoms in molecules revealed a charge transfer according to the Sr(1.3+)Li(0.8+)As(2.1-), in agreement with the electronegativities of the individual elements. The electron localizability indicator distribution indicated the formation of a 3D anionic framework [LiAs] in o-SrLiAs and a rather 2D anionic framework [LiAs] in h-SrLi(1-x)As. Magnetic susceptibility measurements point to a diamagnetic character of both phases, which verifies the calculated electronic density of states.

The new metastable binary silicides MSi(3) (M = Ca, Y, Lu) have been synthesized by high-pressure, high-temperature reactions at pressures between 12(2) and 15(2) GPa and temperatures from 900(100) to 1400(150) K. The atomic patterns comprise intricate silicon layers of condensed molecule-like Si(2) dimers. The alkaline-earth element adopts the oxidation state +2, while the rare-earth and transition metals realize +3. All of the compounds exhibit BCS-type superconductivity with weak electron-phonon coupling below critical temperatures of up to 7 K.

The ternary boron compounds TM(7)TM'(6)B(8) (TM = Ta, Nb; TM' = Ru, Rh, Ir) were prepared by high-temperature thermal treatment of mixtures of the elements. An analysis of the chemical bonding by the electron density/electron localizability approach reveals formation of covalently bonded polyanions [B(6)] and [TM'(6)B(2)]. The cationic part of the structure contains separated TM cations. In agreement with the chemical bonding analysis and band structure calculations, all TM(7)TM'(6)B(8) compounds are metallic Pauli-paramagnets (TM' = Ru, Rh) or diamagnets (TM' = Ir).

CaGe(3) has been synthesized at high-pressure, high-temperature conditions. The atomic pattern comprises intricate germanium layers of condensed moleculelike dimers. Below T(c) = 6.8 K, type II superconductivity with moderately strong electron-phonon coupling is observed.

Synthetic, structural, thermogravimetric, Mössbauer spectroscopic, and magnetic studies were performed on two new isotypic germanophosphates, M(II)(4)(H(2)O)(4)[Ge(OH)(2)(HPO(4))(2)(PO(4))(2)] (M(II) = Fe, Co), which have been prepared under hydro-/solvo-thermal conditions. Their crystal structures, determined from single crystal data, are built from zigzag chains of M(II)O(6)-octahedra sharing either trans or skew edges interconnected by [GeP(4)O(14)(OH)(4)](8-) germanophosphate pentamers to form three-dimensional neutral framework structure. The edge-sharing M(II)O(6)-octahedral chains lead to interesting magnetic properties. These two germanophosphates exhibit a paramagnetic to antiferromagnetic transition at low temperatures. Additionally, two antiferromagnetic ordering transitions at around 8 and 6 K were observed for cobalt compound while only one at 19 K for the iron compound. Low-dimensional magnetic correlations within the octahedral chains are also observed. The divalent state of Fe in the iron compound determined from the Mössbauer study and the isothermal magnetization as well as thermal analyses are discussed.

Dark red crystals of Y₈S(14.8), Tb₈S(14.8), Dy₈S(14.9), and Ho₈S(14.9) have been obtained following different reaction routes. The isostructural title compounds adopt the Gd₈Se₁₅ type, a 24-fold superstructure of the ZrSSi-type and can be described in space group A112 (non standard setting of C121, no. 5) with lattice parameter of a = 11.505(1) Å, b = 15.385(1) Å, c = 15.726(1) Å, and γ = 90.21(2)° for Y₈S(15-x); a = 11.660(1) Å, b = 15.468(2) Å, c = 15.844(2) Å, and γ = 90.19(2)° for Tb₈S(15-x); a = 11.584(1) Å, b = 15.340(2) Å, c = 15.789(2) Å, and γ = 90.34(2)° for Dy₈S(15-x); and a = 11.538(1) Å, b = 15.288(2) Å, c = 15.740(2) Å, and γ = 90.23(1)° for Ho₈S(15-x), respectively. The structure consists of an alternating stacking of puckered [RES] (RE, rare-earth metals) double slabs and planar sulfur layers along [001]. The planar sulfur layers have a complex arrangement of S₂²⁻ dinuclear dianions, isolated S²⁻ ions, and vacancies. All compounds contain trivalent rare-earth metal ions, for Tb₈S(15-x) and Dy₈S(15-x) antiferromagnetic order was found at T(N) = 5.4(2) K and 3.8(1) K, respectively. Short wavelength cutoff optical band gaps of 1.6 to 1.7 eV were determined.

Structural, magnetic, and powder and single-crystal electron paramagnetic resonance (EPR) studies were performed on [{Cu(bipy)(en)}{Cu(bipy)(H(2)O)}{VO(3)}(4)](n) (bipy = 2,2'-bipyridine, en = ethylenediamine), which is a new copper-vanadium hybrid organic-inorganic compound containing Cu(II) and V(V) centers. The oxovanadium units provide an anionic scaffolding to the structure, where two types of Cu(II) coordination modes, octahedral (Cu1) and square pyramidal (Cu2), contribute to the magnetic properties. The crystal structure contains layers including Cu1 and Cu2 ions, separated by stacked arrangements of 2,2'-bipyridine molecules. Each type of Cu(II) ion in these layers forms parallel spin chains described by exchange coupling parameters J(1) and J(2) for Cu1 and Cu2, respectively (exchange couplings defined as H(ex)(i,j) = -J(ij)S(i)S(j)), which, for necessity, are assumed to be equal to J. These chains are coupled by much weaker Cu1-Cu2 exchange interactions J(3) connecting neighbor Cu1 and Cu2 ions within a layer, through paths acting as rungs of a ladder chain structure. The average coupling J, which is antiferromagnetic (J < 0), according to the susceptibility data, is estimated with similar results with a mean field approximation (J = -1.4 cm(-1)), and with a uniform chain model (J = -1.7 cm(-1)). The EPR spectra of powdered samples and oriented single crystals are shown to be independent of J(1) and J(2), but are dependent on the weak coupling J(3), and the data allow a lower limit to be established: |J(3)| > 0.04 cm(-1). The spectra are also strongly sensitive to extremely weak coupling interactions with average magnitude J(4) between copper atoms in neighboring layers, separated by ∼10 Å, using the stacked 2,2'-bipyridine molecules, which produce a 2D-to-3D quantum phase transition. This is observed in single-crystal samples when the energy levels are changed with the orientation of the magnetic field. From the characteristics of these transitions, we estimate a value of |J(4)| = 0.0034 ± 0.0004 cm(-1) between Cu(II) ions in neighboring layers. This work emphasizes the important possibilities of EPR to evaluate extremely small exchange couplings between metal ions in a solid material, even in the presence of other much larger couplings.

The clathrate-I phase Ba(8-x)Si(46) (space group Pm3̅n) was synthesized by oxidation of Ba(4)Li(2)Si(6) with gaseous HCl. Microcrystalline powders of the clathrate phase were obtained within a few minutes. The reaction temperature and the pressure of HCl were optimized to achieve good-quality crystalline products with a composition range of 1.3 < x < 1.9. The new preparation route presented here provides an alternative to the high-pressure synthesis applied so far.

Single crystals of Ba(8)Au(5.3)Ge(40.7) [space group Pm(3)n (No. 223), a = 10.79891(8) Å] were prepared by a Bridgman technique. The crystal structure refinement based on single-crystal X-ray diffraction data does not reveal any vacancies in the Au/Ge framework or in the cages. In addition to the ionic bonding between Ba and the anionic framework, a direct interaction between Ba and Au atoms was identified in Ba(8)Au(5.3)Ge(40.7) by applying the electron localizability indicator. As expected by the chemical-bonding picture, Ba(8)Au(5.3)Ge(40.7) is a diamagnet and shows p-type electrical conductivity with a hole carrier concentration of 7.14 × 10(19) cm(-3) at 300 K and very low lattice thermal conductivity of ≈0.6 W m(-1) K(-1) at 500 K. The thermoelectric figure of merit ZT of single crystals of Ba(8)Au(5.3)Ge(40.7) attains 0.3 at 511 K and reaches 0.9 at 680 K in a polycrystalline sample of closely similar composition. This opens up an opportunity for tuning of the thermoelectric properties of materials in the Ba-Au-Ge clathrate system by changing the chemical composition.

A series of cluster-based ruthenium zinc antimonides with a large unit cell were obtained. Their structures were solved by the single crystal X-ray diffraction methods. They crystallize in the cubic space group of Fm3̅c (No. 226) with cell dimensions of 25.098(3), 24.355(3), 24.307(3), and 24.376(3) Å for Ru(26)Sb(24)Zn(67) (CA), Ru(13)Sb(12)Zn(83.4) (CB), Ru(13)Sb(6.29)Zn(91.56) (CC), and Ru(13)Sb(17.1)Zn(74.8) (CD), respectively. By all indications, compounds CA and CB are two phases showing pronounced distinctions regarding compositions, lattice parameters, thermal and transport properties, but they are not members of an extended solid solution. Compounds CB, CC, and CD are three members of a same solid solution. Topologically, these four compounds contain face-centered cubic packing of double-Mackay type clusters and (Sb(1-δ)Zn(δ))(24) snub cubes filled with highly disordered zinc aggregates, with or without glue atoms between them. Both phases CA and CB are diamagnetic. There is a difference of ∼170 K between their thermally stable temperatures. CA exhibits rather low thermal conductivity with the value of ∼0.9 W m(-1) K(-1) at room temperature, which is about one-third that of CB. The electrical resistivity of CB is almost temperature independent. The Seebeck coefficient of CB is small and negative, while that of CA exhibits a complicated temperature dependence and undergoes a transition from p- to n-type conduction around room temperature.

A new potassium palladate KPd(2)O(3) was synthesized by the reaction of KO(2) and PdO at elevated oxygen pressure. Its crystal structure was solved from powder X-ray diffraction data in the space group R3m (a = 6.0730(1) A, c = 18.7770(7) A, and Z = 6). KPd(2)O(3) represents a new structure type, consisting of an alternating sequence of K(+) and Pd(2)O(3)(-) layers with ordered Pd(2+) and Pd(4+) ions. The presence of palladium ions in di- and tetravalent low-spin states was confirmed by magnetic susceptibility measurements.

The synthesis and single crystal growth of clathrate-II Na(24)Si(136) is performed in one step applying the spark plasma treatment to the precursor Na(4)Si(4). The reported results demonstrate a new route to intermetallic compounds facilitated by the electric field and current. SPS is revealed to offer significant opportunities as a novel preparatory method for synthesis and crystal growth of solid state materials.

The chemical bonding in the isostructural intermetallic compounds TiSb2 and VSb2, crystallizing in the CuAl2 type, was investigated by means of quantum chemical calculations, particularly the electron localization function (ELF), as well as by Raman spectroscopy, Hall effect and conductivity measurements on oriented single crystals, and high-pressure X-ray powder diffraction. The homogeneity ranges of the compounds were determined by powder X-ray diffraction, WDXS, and DSC measurements. TiSb2 exhibits no significant homogeneity range, while VSb2 shows a small homogeneity range of approximately 0.3 at. %. According to the ELF calculations, the Sb atoms form dumbbells via a two-center two-electron bond, while the T atoms (T = Ti, V) build up chains along the crystallographic c-axis. Both building units are connected by covalent T-Sb-T three-center bonds, thus forming a three-dimensional network. The strength of the bonds involving Sb was determined by fitting a force constant model to the vibrational mode frequencies observed by polarized Raman measurements on oriented single crystals. The resulting bond order of the Sb2 dumbbells is 1, while the strength of the three-center bonds resembles a bond order of 1.5. The weak pressure dependence of the c/a ratio confirms the slightly different bonding picture in TiSb2 compared to that in CuAl2. Electrical transport measurements show the presence of free charge carriers, as well as a metal-like temperature dependence of the electrical resistivity.

Three novel isotypic borophosphates M(II)[BPO4(OH)2] (M(II) = Mn, Fe, Co) have been hydrothermally synthesized and structurally characterized. The isotypic compounds crystallize in the chiral space group P3(1)21 or P3(2)21. Their crystal structures are characterized by edge-sharing helical M(II)O6-octahedral chains wound around 3(1) or 3(2) screw axes (along [001]) interconnected by borophosphate single chains of alternating BO2(OH)2 and PO4 tetrahedra perpendicular to [001], resulting in three-dimensional framework structures. The helical M(II)O6-octahedral chains lead to low-dimensional magnetic properties.

A first rare-earth phosphide silicide Ce4(P(1-x)Si(x))(3-z) and its analogues with La, Pr, and Nd were synthesized and characterized. The compounds crystallize in the anti-Th3P4 structure type. The cerium compound shows a mixed occupation of the 12a site with Si and P and possesses a wide homogeneity range with respect to x and z variation. The electronic configuration of Ce, deduced from magnetic susceptibility and X-ray absorption spectroscopy data, remains 4f(1) (Ce3+) independently from x and z. The cerium valence and the phase stability region are discussed employing electronic band-structure calculation and chemical bonding analysis with electron localization function. Atomic interactions are shown to remain nearly unchanged, while the change of the excess electron concentration with P/Si substitution is considered to play the main role for the stabilization of the structural motif.

Two new hybrid organic/inorganic copper oxovanadium diphosphonates [Cu2(phen)2(O3PCH2PO3)(V2O5)(H2O)] x H2O (1) and [(Cu2(phen)2(O3P(CH2)3PO3)(V2O5)] x C3H8 (2) have been obtained by hydrothermal synthesis. The compounds are monoclinic, and they crystallize in the space group P2(1)/n with cell parameters of a = 11.788(2) A, b = 17.887(3) A, c = 14.158(2) A, and beta = 93.99(0) degrees and in the space group C2/c with cell parameters of a = 11.025(1) A, b = 18.664(2) A, c = 15.054(2) A, and beta = 90.06(0) degrees, respectively. Both compounds present two-dimensional frameworks built up from infinite chains of corner-sharing vanadium tetrahedra and diphosphonate groups connected by copper tetramers for (1) and copper dimers for (2). The remarkable feature of (2) is the encapsulation of propane molecules, stabilized by strong hydrogen bonding between the layers. The magnetic properties of the compounds have been investigated showing antiferromagnetic coupling with Tmax = 64 K for (1) and Curie-like paramagnetic behavior for (2).

Sn19.3Cu4.7As22I8, a new clathrate-I compound with a cationic host framework containing transition metals, has been synthesized, and its crystal structure has been determined. It crystallizes in the cubic space group Pmn with a unit cell parameter a = 11.1736(3) angstroms and Z = 1 (R = 0.031 for 329 independent reflections and 22 variables). Tin, copper, and arsenic form the cationic clathrate framework hosting the guest iodine anions in cages of two different shapes. Sn19.3Cu4.7As22I8 does not contain vacancies in the framework but reveals three partially occupied positions of the metal atoms, leading to the formation of Sn-Sn and Sn-Cu bonds that differ in length. The 119Sn Mössbauer spectrum confirms the local environment of tin atoms. The hyperfine constants obtained from the Mössbauer spectra for different cationic tin clathrates are discussed. Electron diffraction and electron microscopy reveal that the splitting affects the short-range ordering but does not lead to a superstructure. Though containing a transition metal, Sn19.3Cu4.7As22I8 is diamagnetic, and its composition corresponds to the Zintl formalism.

Stoichiometric barium pernitride, BaN(2), was prepared from the elements under N(2) pressure of 5600 bar in an autoclave at 920 K. The compound is isotypic to ThC(2) (space group C2/c, Z = 4) according to powder X-ray (neutron) diffraction data with a = 7.1712(1), b = 4.3946(1), c = 7.2362(1) A, and beta = 104.864(1) degrees (a = 7.1745(1), b = 4.3963(1), c = 7.2393(1) A, beta = 104.876(1) degrees ). The N-N distance of 1.221(4) A (based on the neutron diffraction data) is indicative of a double bond in the N(2)(2-) dumbbells. BaN(2) is metallic according to magnetic susceptibility measurements and TB-LMTO band structure calculations.