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Electron-rich [Fe(CN)4]6− features a π-backbonding scheme with non-innocent CN-ligands exhibiting weak C–N bonds and a d10 configuration on iron.

Large single crystals of Li2(Ca3N)2[Ga4] and Li2(Sr3N)2[Ga4] up to several mm in size were grown from mixtures of the respective elements and binary alkaline-earth metal nitrides in reactive lithium melts employing a modified high-temperature centrifugation-aided filtration (HTCAF) technique. The main structural features of these isotypic phases are stella quadrangula building units [Ga4]Li4/2 and octahedra (Nae6/2), which form two independent interpenetrating networks. The phases crystallize in the η-carbide structure and represent diamagnetic small bandgap semiconductors. Real-space chemical bonding analysis indicates predominantly ionic bonding.

The unprecedented, fully deprotonated form of acetonitrile, the acetonitriletriide anion CCN3−, is experimentally realized for the first time in the stabilizing bulk host framework of the Ba5[TaN4][C2N] nitridometalate via a one-pot synthesis from the elements under moderate conditions (920 K). The molecular structure of this long-sought acetonitrile derivative is confirmed by X-ray diffraction, as well as NMR, IR, and Raman spectroscopy. The anion is isoelectronic to the CO2 molecule, and, in contrast to acetonitrile (H3C−C≡N), the electron pairs are shifted towards two double bonds, that is, [C=C=N]3−.

Up to now, investigation of physical properties of ternary and higher nitridometalates was severely hampered by challenges concerning phase purity and crystal size. Employing a modified lithium flux technique, we are now able to prepare sufficiently large single crystals of the highly air and moisture sensitive nitridoferrate $\rm Li_2Sr[Li_{1-x}Fe_xN]_2$ for anisotropic magnetization measurements. The magnetic properties are most remarkable: large anisotropy and coercivity fields of 7 Tesla at $T = 2$ K indicate a significant orbital contribution to the magnetic moment of iron. Altogether, the novel growth method opens a route towards interesting phases in the comparatively recent research field of nitridometalates and should be applicable to various other materials., Comment: 10 pages, 5 figures, published open access in Inorganics, minor typos corrected

The title compound Ca_3[BN_2]I_3 was obtained from reactions of mixtures of the starting materials Ca_3[BN_2]_2 and CaI_2 in a 1:4 ratio in sealed Nb tubes at 1223 K. The crystal structure was solved from powder synchrotron diffraction data. Ca_3[BN_2]I_3 is the first example of a halide-rich nitridoborate crystallizing in the rhombohedral space group R32 [no. 155, Pearson code: hR96; Z = 12; a = 16.70491(2) A, c = 12.41024(2) A]. The crystal structure is built up by two interpenetrating networks of condensed edge-sharing [BN_2]@Ca_6 and [□]@I_6 trigonal antiprisms (□ = void). In Ca_3[BN_2]I_3 two crystallograhically distinct [BN_2]^(3–) anions are present with d(B1–N) = 1.393(2) A and d(B2–N) = 1.369(9) A. Their bond angles are practically linear, varying only slightly: N–B1–N = 179(1)° and N–B2–N = 180°. Vibrational spectra were interpreted based on the D_(∞h) symmetry of the discrete linear [N–B–N]^(3–) moieties, considering the site symmetry reduction and the presence of two distinct [BN_2]^(3–) groups.

Brownish gray microcrystalline powders of Ba3[Rh(CN)3] were synthesized from pellets of mixtures of Ba2N, rhodium, NaCN, and graphite at 1070 K in an argon atmosphere. Synchrotron powder diffraction data at 293(1) K revealed the crystal structure of the compound [P63/m, a = 9.23266(7) A, c = 5.81612(6) A] is isostructural to Ba3[Co(CN)3] and Ba3[Ir(CN)3]. The trigonal-planar complex [Rh(CN)3]6– is surrounded by nine Ba2+ cations forming a tri-capped trigonal prism. Compared to typical cyano ligands, the C–N bond is long [1.21(5) A] and the vibrational frequencies are low (IR 1674 cm–1, Raman 1728 cm–1).

Na3[BN2] and Na2K[BN2] were obtained as white polycrystalline powders from the reaction of the respective binary mixtures NaNH2:NaBH4 and NaNH2:KBH4 in molar ratio 2:1 at 873 K and 683 K, respectively, in an argon stream. According to the results of thermal analysis measurements, both compounds are thermally stable only up to 954 K (Na3[BN2]) and 712 K (Na2K[BN2]), respectively, decomposing under evolution of alkali metal and nitrogen to yield hexagonal BN as final residue, which was identified from powder patterns. The crystal structure of Na3[BN2] {β-Li3[BN2] type; P21/c (No. 14); Z = 4} was confirmed and the unit cell parameters redetermined: a = 5.724(1) A, b = 7.944(1) A, c = 7.893(1) A, β = 111.31(1)°. According to X-ray powder data, Na2K[BN2] crystallizes isotypic to Na2KCuO2 in the tetragonal space group I4/mmm (No. 139) with a = 4.2359(1) A, c = 10.3014(2) A and Z = 2. The crystal structure of Na2K[BN2] is composed of linear [N–B–N]3– anions centering elongated M14 rhombic dodecahedra, which are formed by 8 sodium and 6 potassium atoms. The [BN2]@Na8/4K6/6 polyhedra are stacked along [001] and condensed via common tetragonal faces to generate a space-filling 3D arrangement. The B–N bond lengths for the strictly linear [N–B–N]3– units are 1.357(4) A. Vibrational spectra of the title compounds were measured and analyzed based on D∞h symmetry of the relevant [N–B–N]3– groups taking into account the site symmetry effects for Na3[BN2]. Both the wavenumbers, as well as the calculated valence force constants f(B–N) = 7.29 N·cm–1 (Na3[BN2]) and 7.33 N·cm–1 (Na2K[BN2]), respectively, are in good agreement with those of the known alkali and alkaline earth dinitridoborates.

Mg2[BN2]Br was prepared from stoichiometric mixtures of the respective binary components Mg3N2, MgBr2 and BN in sealed niobium ampoules placed in evacuated silica tubes at 1473 K. The monoclinic crystal structure (C2/c (no. 15); a = 9.1509(3) A, b = 6.6209(3) A, c = 6.4756(2) A, β = 109.353(3)° and Z = 4) was determined from powder data. The crystal structure is characterized by cationic 32.4.3.4 nets of magnesium and anionic hexagonal closed packed 36 nets of six-connected nodes occupied by [N–B–N]3– units and Br– anions. Both types of planar nets alternate along the [100] direction. The packing of such incoherent nets results in a monoclinic symmetry, which is a compromise for a structure built up from rod-like [N–B–N]3– units and spherical bromine and magnesium atoms. Bond length and bond angle for the [N–B–N]3– unit are d(B–N) = 1.354(2) A and ∠(N–B–N) = 177.1(9)°, respectively., Vibrational spectra were analyzed based on the D∞h symmetry of the relevant [N–B–N]3– moieties, considering the site symmetry splitting. The results are discussed in context with those of the known members of the magnesium dinitridoborate halide series, Mg2[BN2]Cl and Mg8[BN2]5I.

The mixed-valent nitridomanganate Ba4[Mn3N6] was prepared using a gas–solid high temperature route. The crystal structure was determined employing high resolution synchrotron powder diffraction data: space group Pbcn, a = 9.9930(1) Å, b = 6.17126(8) Å, c = 14.4692(2) Å, V = 892.31(2) Å3, Z = 4. The manganese atoms in the structure of Ba4[Mn3N6] are four-fold coordinated by nitrogen forming infinite corrugated chains of edge-sharing [MnN4] tetrahedra. The chains demonstrate a complete charge order of Mn species. Magnetization measurements and first principle calculations indicate quasi-one dimensional magnetic behavior. In addition, chemical bonding analysis revealed pronounced Mn–Mn interactions along the chains.

The transparent dark orange compounds Cs2[Pd(N3)4] and Rb2[Pd(N3)4]·2/3H2O are synthesized by reaction of the respective binary alkali metal azides with K2PdCl4 in aqueous solutions. According to single-crystal X-ray diffraction investigations, the novel ternary azidopalladates(II) crystallize in the monoclinic space group P21/c (no. 14) with a = 705.7(2) pm, b = 717.3(2) pm, c = 1125.2(5) pm, β = 104.58(2)°, mP30 for Cs2[Pd(N3)4] and a = 1041.4(1) pm, b = 1292.9(2) pm, c = 1198.7(1) pm, β = 91.93(1)°, mP102 for Rb2[Pd(N3)4]·2/3H2O, respectively. Predominant structural features of both compounds are discrete [PdII(N3)4]2– anions with palladium in a planar coordination by nitrogen, but differing in point group symmetries., The vibrational spectra of the compounds are analyzed based on the idealized point group C4h of the spectroscopically relevant unit, [Pd(N3)4]2– taking into account the site symmetry splitting due to the symmetry reduction in the solid phase.

Sr6[CoN2]2[CN2] was prepared from Sr2N, carbon, cobalt, and NaN3 as nitrogen source. The crystal structure (I4/mmm (no. 139), a = 383.55(10) pm, c = 1237.8(4) pm) represents a Na2[HgO2] type arrangement with both linear [CoIN2]5– and smaller [CN2]2– ions mutually occupying the [HgO2] position.

Ca5N5V, orthorhombic, Pbcm (no. 57), a = 6.0371(3) Å, b = 16.6146(7) Å, c = 6.7815(3) Å, V = 680.21(5) Å3, Z = 4, R(P) = 0.0100, RF(all) = 0.0348, T = 293 K.

The formation of ternary nitridometalates from the elements in the case of the systems Li—Cr, V, Mn—N leads to compounds which contain the transition metals in the highest (VV, CrVI) or a comparably high (MnV) oxidation state. In the corresponding calcium and strontium systems, the transition metals show a lower oxidation state (VIII, CrIII, MnIII). Transition metals with intermediate oxidation states (CrV, MnIV) are present in the quaternary (mixed cation) compounds Li4Sr2[CrN6], Li6Ca2[MnN6], and Li6Sr2[MnN6] (R3¯(#148), a = 585.9(3) pm, c = 1908.6(4) pm, Z = 3), as well as in the solid solution series Li6(Ca1—xSrx)2[MnN6]. Zur Kontrolle der Oxidationsstufen von Ubergangsmetallen (Cr, Mn) in Nitridometallaten und zur Kenntnis der Mischkristallreihe Li6(Ca1-xSrx)[Mn2N6] Bei der Darstellung aus den Elementen liegt in ternaren Nitridometallaten des Vanadiums, Chroms und Mangans das Ubergangsmetall in den Lithiumverbindungen in der hochstmoglichen (VV, CrVI) oder einer hohen Oxidationsstufe (MnV) vor, in den entsprechenden Calcium- und Strontium-Verbindungen in einer niedrigeren (VIII, CrIII, MnIII). In den quaternaren Verbindungen Li4Sr2[CrN6], Li6Ca2[MnN6] und Li6Sr2[MnN6] (R3¯(#148), a = 585.9(3) pm, c = 1908.6(4) pm, Z = 3) sowie der Mischkristallreihe Li6(Ca1—xSrx)2[MnN6] weist das Ubergangsmetall dagegen eine mittlere Oxidationsstufe auf (CrV, MnIV).

Greenish gray microcrystalline powders of Ba3[Ir(CN)3] were prepared from pressed pellets of mixtures of Ba2N, iridium, NaCN, and graphite at 1020 K under inert conditions. Neutron diffraction data at 293 K revealed the crystal structure of the Ir compound (P63/m (no. 176), a = 9.2277(8) A, c = 5.7878(6) A) to be isostructural to Sr3[Co(CN)3] and Ba3[Co(CN)3]. The trigonal-planar complex [Ir3(CN)3]6– is surrounded by nine Ba2+ ions forming a tricapped trigonal prism. Elongated C–N distances and low vibrational frequencies in the highly reduced iridium complex are similar to those observed in the corresponding cobalt compounds.

Sr5[NbN4]N (transparent, red single crystals) was synthesized by reaction of Sr2N with Nb under nitrogen at ambient pressure and 1223 K. The crystal structure was solved and refined in the space group Pbcm (no. 57), Z = 4, with lattice constants a = 646.6(3) pm, b = 1792.5(9) pm, c = 729.8(4) pm, and R = 0.019, wR2 = 0.034. The crystal structure contains both isolated tetrahedra [NbN4]7- as well as chains of corner sharing octahedra 1(Sr4Sr2/2N7+). Strontium is irregularly coordinated by nitrogen (CN = 4 - 6, Sr-N: 252.3(4) - 340.8(3) pm); nitrogen is located in a distorted octahedral environment by strontium and niobium (Nb-N: 194.5(4) - 199.2(2) pm). By formal reduction of the structural building units to their centers a close structural relationship to both the NiAs and the CaSi type structure is evident.

The reinvestigation of the binary system Ba-Ni revealed the existence of Ba2Ni3 in the temperature range 450 °C–800 °C. Single crystals were grown at 700 °C in the presence of excess barium, followed by separation from the melt by use of the high-temperature centrifugation aided filtration technique, HTCAF. At ambient temperature Ba2Ni3 is in a metastable state which slowly transforms to the elements (side-phases of the binary system). The extreme softness and the mechanical instability of the hygroscopic Ba2Ni3 particles prevented a single crystal structure determination. The crystal structure was solved from X-ray powder diffraction data (Pm1 (No. 164), a = 419.97(2) pm, c = 913.32(3) pm) and revealed Ba2Ni3 to be an isotype of Sr2Ni3 which was reported only recently.

The crystal structure of a new potassium tantalum(V) cyclotetrasilicate, KTaSi{sub 2}O{sub 2} (K{sub 2}Ta{sub 2}Si{sub 4}O{sub 14}), has been determined by single crystal X-ray diffraction. KTaSi{sub 2}O{sub 7} crystallizes in the tetragonal system, space group P4/mbm with {alpha} = 8.735(2) and c= 7.999(2) {Angstrom}, V= 610.3(2) {Angstrom}{sup 3}, Z = 4, d{sub x} = 4.225 g/cm{sup 3}, {lambda} (MoK{alpha}) = 0.71073 {Angstrom}, {mu} = 190.7 cm{sup {minus}1}, F{sup {prime}} (000) = 704, T = 293 K, R = 0.0421, R{sub w} = 0.0789 for 451 unique reflections (R{sub int} = 0.0227) with F{sub O}{sup 2} > O. The framework structure of KTaSi{sub 2}O{sub 7} is built up from chains of corner-sharing TaO{sub 6} octahedra running parallel to the fourfold axes and linked together by four-membered Si{sub 4}O{sub 12} single units. AC impedance measurements on KTaSi{sub 2}O{sub 7} indicate low ionic conductivities, 5.6 x 10{sup {minus}9} and 3.0 x 10{sup {minus}7} {Omega} {center_dot} cm{sup {minus}1} at 333 and 546{degrees}C, respectively. An activation energy of 0.83 {plus_minus} 0.02 eV is observed.

Co2N4Sr5, tetragonal, P4/ncc (no. 130), a = 8.6730(5) Å, c = 12.443(1) Å, V = 936.0 Å3, Z = 4, Rgt(F) = 0.0293, wRref(F2) = 0.0684, T = 295 K.

The title compounds Sr-2[BN2]Br (1), Eu-2[BN2]Br (2) and Eu-2[BN2]I (3) were obtained from reactions of mixtures of Sr-3[BN2](2) and SrBr2 (1) and the binaries EuN, h-BN and EuX2 (X = Br, I) (2, 3), respectively. The crystal structure of Sr-2[BN2]Br was solved from X-ray powder diffraction data and those of the europium compounds from X-ray single crystal data. Sr-2[BN2]Br and Eu-2[BN2]Br are isotypic crystallizing in the rhombohedral space group R (3) over barm (No. 166, Pearson code: hR18; Z = 3; a = 4.11692(2) angstrom, c = 26.4611(2) angstrom (1); a = 4.0728(3) angstrom, c = 26.589(3) angstrom (2)). The crystal structures are built up by layers of condensed edge-sharing [B-N-B]@Eu-6 and [Br]@Eu-6 trigonal antiprisms, which are alternately stacked along [001] Eu-2[BN2]I - isotypic to Sr-2[BN2]I - crystallizes in the monoclinic space group P2(1)/m (No. 11, Pearson code: mP24; Z = 4; a = 10.2548(6) angstrom, b = 4.1587(3) angstrom, c = 13.1234(9) angstrom, beta = 91.215(4)degrees). The crystal structure is characterized by slightly puckered layers formed by condensed edge-sharing I@Eu-6 octahedra which are separated by isolated [BN2](3-) units. The bond lengths for the strictly linear [BN2](3-) anions in (1) and (2) are d(B-N) = 1.351(4) angstrom and 1.356(8) angstrom, respectively. In Eu-2[BN2]I two crystallograhically distinct [BN2](3-) anions are present with d(B1-N) = 1.32(4) angstrom, 1.37(4)angstrom and d(B2-N) = 1.30(4) angstrom, 1.34(4) angstrom, respectively. Their bond angles vary slightly: angle(N-B1-N) = 179(3)degrees and angle(N-B2-N) = 177(3)degrees. The magnetic susceptibility data of the europium compounds (2) and (3) indicate that the Eu ions are divalent with 4f(7) configuration. Vibrational spectra were measured and interpreted based on the D infinity(h) symmetry of the discrete linear [N-B-N](3-) moieties, considering the site symmetry reduction and the presence of two distinct [BN2](3-) groups in (3)., NA

In the course of our current research on quaternary phases in the systems Sr-Ni-C-N, we are also interested in binary phases of the system Sr Ni, in order to use them starting material for reactions. The binary system Sr Ni was first investigated in 1966. According to this study, SrNi is the only intermediate phase. Our recent investigation of the same system (Figure 1) did not confirm the existence of

Die isotypen Phasen Ca6GaN5 und Ca6GeN5 (hexagonal, P63/mem; a = 627, 7(3)/623,7(1) pm, c = 1219,8(3)/1233,2(6) pm; Z = 2) werden durch Reaktion von Gemischen aus Ca und Ga (molares Verhaltnis 6:1) bzw. Fe, Ca3N2 und Ca (molare Verhaltnisse zwischen 3:1:13 und 5:2:15) mit Stickstoff bei Temperaturen von 850°C bzw. 950°C bis 1100°C erhalten. Als wesentliche Strukturmerkmale treten carbonat-isostere, trigonal-planare Anionen [MN3]6− auf (GaN: 195,1(28) pm; FeN: 177,0(15) pm). Enge Verwandtschaft besteht zu den Kristallstrukturen von Verbindungen der Hydrotalkit-Gruppe. Ca6GaN5 and Ca6FeN5: Compounds Containing [CO3]2−-isosteric Anions [GaN3]6− and [FeN3]6− The isotypic phases Ca6GaN5 and Ca6FeN5 (hexagonal, P63/mem; a = 627.7(3)/ 623,7(1) pm, c = 1219.8(3)/1233.2(6) pm; Z = 2) are prepared by reaction of Ca/Ga mixtures (molar ratio 6:1) and Fe/Ca3N2/Ca mixtures (molar ratios from 3:1:13 to 5:2:15) with nitrogen at temperatures of 850°C and 950°C to 1100°C, respectively. The structures contain trigonal-planar anions [MN3]6− which are isosteric to carbonate ions (GaN: 195,1(28) pm; FeN: 177,0(15) pm). The structures are closely related to those compounds of the hydrotalcite group.

Synthesis, crystal structure as well as IR- and Raman-spectroscopic properties of the new ternary azidoaurates(III) A[Au(N3)4] (A = K, Rb, Cs) are reported. The translucent orange-red compounds were prepared by reaction of the respective binary azides with HAuCl4 in aqueous solutions at room temperature. The crystal structures determined by single crystal X-ray diffraction methods are monoclinic (C2/c (No. 15), K/Rb/Cs[Au(N3)4]: a = 1049.30(9) pm / 1033.93(10) pm / 1011.9(8) pm, b = 1047.52(8) pm / 1064.20(11) pm / 1093.8(8) pm, c = 776.97(7) pm / 809.79(8) pm / 858.4(6) pm, β = 91.220(5)° / 90.322(5)° / 92.72(5)°) and provide the first examples for azidoaurates with mono-atomic cations. The unusual reduction of the lattice parameter a with increasing cation size in the isotypic series is discussed in detail. IR- and Raman-spectroscopic measurements show strongly covalent gold-nitrogen contacts, a bonding situation which is further supported by quantum chemical calculations and ELF-analyses.

CrN4Sr3, orthorhombic, Pbca (No. 61), a = 10.199(1) Å, b = 9.566(1) Å, c = 11.169(2) Å, V = 1089.6 Å3, Z = 8, R(P) = 0.082, R(I) = 0.053, T = 293 K.