Neue ternäre Phosphide und Arsenide mit einem Metall : Nichtmetall‐Verhältnis im Bereich von 2 : 1

New Ternary Phosphides and Arsenides with a Metal : Non‐Metal Ratio in the Range of 2 : 1 Six new compounds were prepared by heating mixtures of the elements or by reaction of them in a tin(lead) flux. They were investigated by single crystal X‐ray methods. Sc₂Ni₁₂P₇ (a = 9.013(1), c = 3.590(1) Å) crystallizes in the Zr₂Fe₁₂P₇ type structure (P6; Z = 1), which is basically built up likewise by Eu₂Pd₁₂As₇ (a = 10.040(1), c = 4.100(1) Å) and Sr₂Rh₁₂P₇ (a = 9.626(1), c = 3.844(1) Å), but one of seven non‐metal atoms has a somewhat modified environment and is disordered along [001]. Therefore their crystal structure corresponds to the Ho₂Rh₁₂As₇ type structure (P6₃/m; Z = 1). Ca₂Ni₇P₄ (a = 3.703(1), b = 9.209(1), c = 10.378(1) Å) forms the Nd₂Ni₇P₄ type structure (Pmn2₁; Z = 2), whereas the atomic arrangements of Ca₄Rh₁₃As₉ (a = 3.903(2), b = 11.221(1), c = 19.411(4) Å) and Sm₄Rh₁₃As₉ (a = 3.913(2), b = 11.242(6), c = 19.440(6) Å) correspond basically to the Ho₄Ir₁₃Ge₉ type structure (Pmmn; Z = 2), but the disorder of Rh8 required the occupation of splitting positions. The transition metals have three, four or five neighbouring atoms of phosphorus or arsenic and form together with them three‐dimensional covalent frameworks, of which holes are occupied by the atoms of the electropositive metal. Most of the polyhedra around the P and As atoms respectively consist of trigonal prisms of metal atoms with additional metal atoms capping the rectangular faces of the prisms. This environment ist characteristic for ternary phosphides and arsenides with a metal : non‐metal ratio in the range of 2 : 1.     

Synthese und Kristallstrukturen des Zink‐Rhodiumborids Zn5Rh8B4 und der Lithium‐ Magnesium‐Rhodiumboride LixMg5−xRh8B4 (x = 1.1 und 0.5) und Li8Mg4Rh19B12

Synthesis and Crystal Structures of Zinc Rhodium Boride Zn₅Rh₈B₄ and the Lithium Magnesium Rhodium Borides Li_xMg_5?xRh₈B₄ (x = 1.1 and 0.5) and Li₈Mg₄Rh₁₉B₁₂ The title compounds were prepared by reaction of the elemental components in metal ampoules under argon atmosphere (1100 °C, 7 d). In the case of Zn₅Rh₈B₄ (orthorhombic, space group Cmmm, a = 8.467(2) Å, b = 16.787(3) Å, c = 2.846(1) Å, Z = 2) a BN crucible enclosed in a sealed tantalum container was used. The syntheses of Li_xMg_5?xRh₈B₄ (orthorhombic, space group Cmmm, Z = 2, isotypic with Zn₅Rh₈B₄, lattice constants for x = 1.1: a = 8.511(3) Å, b = 16.588(6) Å, c = 2.885(1) Å, and for x = 0.5: a = 8.613(1) Å, b = 16.949(3) Å, c = 2.9139(2) Å) and Li₈Mg₄Rh₁₉B₁₂ (orthorhombic, space group Pbam, a = 26.210(5) Å, b = 13.612(4) Å, c = 2.8530(5) Å, Z = 2) were carried out in tantalum crucibles enclosed in steel containers using lithium as a metal flux. The crystal structures were solved from single crystal X‐ray diffraction data. In both structures Rh atoms reside at z = 0 and all non‐transition metal atoms at z = 1/2. Columns of Rh₆B trigonal prisms running along the c‐axis are laterally connected to form three‐dimensional networks with channels of various cross sections containing Li‐, Mg‐, and Zn‐atoms, respectively. A very short Li‐Li distance of 2.29(7) Å is observed in Li₈Mg₄Rh₁₉B₁₂.     

Neue Erdalkalimetall‐Phosphide und ‐Arsenide des Cobalts

New Alkaline‐Earth Metal Phosphides and Arsenides of Cobalt Five new compounds of cobalt were prepared by heating mixtures of the elements and investigated by means of single crystal X‐ray methods. Mg₂Co₁₂As₇ (a = 12.096(6), b = 3.670(2), c = 24.93(1) Å) crystallizes in a new structure type (Pnma; Z = 4). Most of the Co atoms are coordinated tetrahedrally by arsenic, the other ones in the form of a square pyramid. Due to the linking of these polyhedra channels of hexagonal cross section are formed along [010], in which the Mg atoms are arranged. Mg₂Co₁₂P₇ (a = 9.012(2), c = 3.504(1) Å), Ca₂Co₁₂P₇ (a = 9.073(1), c = 3.585(1) Å) as well as Ca₂Co₁₂As₇ (a = 9.428(5), c = 3.728(2) Å) crystallize in the Zr₂Fe₁₂P₇ structure type (P6; Z = 1). Micro domains of the arsenide required refinements of the structure parameters in space group P6₃/m. MgCo₆P₄ (a = 6.609(1), c = 3.380(1) Å) is isotypic with LiCo₆P₄ (P6m2; Z = 1). The compounds belong to the large family of phosphides and arsenides with a metal : non‐metal ratio of about 2 : 1. Their structures can be described by the linkings of non‐metal centred trigonal prisms of metal atoms with additional metal atoms capping the rectangular faces of the prisms.     

Synthese und Kristallstrukturen der Calcium‐Iridiumsilicide Ca3Ir4Si4 und Ca2Ir2Si

Synthesis and Crystal Structures of the Calcium Iridium Silicides Ca₃Ir₄Si₄ and Ca₂Ir₂Si The new compounds Ca₃Ir₄Si₄ und Ca₂Ir₂Si were prepared by reaction of the elemental components in sealed tantalum ampoules at 1200 °C. Their structures were determined from X‐ray single crystal data. Ca₃Ir₄Si₄(cubic, space group I4¯3m, a = 7.4171(2)Å, Z = 2) crystallizes with the Na₃Pt₄Ge₄ type structure. For Ca₂Ir₂Si (monoclinic, space group C2/c, a = 9.6567(5)Å, b = 5.8252(2)Å, c = 7.3019(4)Å, β = 100.212(2)°, Z = 4) a new structure was found. Chains of edge sharing, heavily distorted SiIr₄‐tetrahedra (Ir‐Si: 2.381 and 2.414Å) are connected via short Ir—Ir‐contacts (2.640Å) to form an open Ir/Si‐framework accommodating a three‐dimensional arrangement of calcium atoms (Ca—Ca: 3.413 ‐ 3.948Å).     

Synthese und Kristallstrukturen ternärer Phosphide und Arsenide des Rhodiums und Iridiums

Ternary Phosphides and Arsenides of Rhodium and Iridium: Synthesis and Crystal Structures Single crystals of eight new compounds were prepared by heating mixtures of the elements in a lead flux. They were investigated by X‐ray methods. Ca₂Ir₁₂P₇ (a = 9.512(1), c = 3.923(1) Å)is an additional representative of the Zr₂Rh₁₂P₇ type structure, micro domains required refinements of the structural parameters in space group P6₃/m. Ca₅Rh₁₉P₁₂ (a = 12.592(1), c = 3.882(1) Å) and Ca₅Ir₁₉P₁₂ (a = 12.577(2), c = 3.954(1) Å) crystallize with the Ho₅Ni₁₉P₁₂ type structure (P6¯2m; Z = 1), whereas the compounds A₆Rh₃₀X₁₉ form a slightly modified structure of the Yb₆Co₃₀P₁₉ type. The lattice constants are: Ca₆Rh₃₀P₁₉: a = 15.532(1) Å, c = 3.784(1) Å Sr₆Rh₃₀As₁₉: a = 16.135(2) Å, c = 3.916(1) Å Eu₆Rh₃₀P₁₉: a = 15.566(1) Å, c = 3.821(1) Å Eu₆Rh₃₀As₁₉: a = 16.124(1) Å, c =5 3.903(3) Å Yb₆Rh₃₀P₁₉: a = 5 15.508(1) Å, c =5 3.770(1) Å Because one of the four non‐metal atoms, located on different crystallographic sites, is disordered along [001] micro domains are formed. Therefore the parameters were not refined in space group P6¯ (Yb₆Rh₃₀P₁₉ type), but in space group P6₃/m. The metal:non‐metal ratio of all compounds is in the range of 2:1. Accordingly most of the non‐metal atoms are coordinated by nine metal atoms, which form tricapped trigonal prisms. These polyhedra are combined with each other in a different way.     

Synthese und Kristallstruktur von Sr2Rh7P6

Synthesis and Crystal Structure of Sr₂Rh₇P₆ Single crystals of Sr₂Rh₇P₆ were obtained by reaction of the elements in molten lead at 1100 °C and investigated by X-ray methods. The compound crystallizes tetragonally (a = 11.080(2), c = 4.098(1) Å) and forms a crystal structure (P 4 2₁m; Z = 2) with ThCr₂Si₂ analogous units, which are linked with each other in a new way. Therefore the RhP₄ tetrahedra form bands of edge sharing chains parallel to [001] anstead of layers as in the ThCr₂Si₂ type structure. The arrangement enables a part of the P atoms to form short P–P distances of 2,26 Å and space for additional Rh atoms with a likewise distorted tetrahedral coordination of P atoms is obtained.     

Mg3Ir3Si8, ein neues Magnesium‐Iridium‐Silicid mit Tetraedern und gekappten Tetraedern aus Silicium‐Atomen

Mg₃Ir₃Si₈, a New Magnesium Iridium Silicide with Si₄ Tetrahedra and Si₁₂ Truncated Tetrahedra The ternary silicide Mg₃Ir₃Si₈ (cubic, a = 1221.4(1) pm, space group , 8 formula units per unit cell) was prepared by reaction of the elemental components in a sealed molybdenum container (1000 °C, 1 d, cooled with 100 °/h). The crystal structure was determined from single crystal data. Short distances in the three‐dimensional iridium silicon network indicate strong Ir‐Si‐bonding (d(Ir‐Si) = 240.5(2) and 245.6(1) pm). In addition, homonuclear bonding seems to be important, resulting in the formation of Si₄‐tetrahedra (d(Si‐Si) = 257(1) pm), and Mg centered Si₁₂‐polyhedra with the shape of truncated tetrahedra (d(Si‐Si) = 241(1) and 261.0(9) pm). Furthermore, Mg₄‐tetrahedra with Mg‐Mg‐distances of 355(2) pm are formed. The structure may be derived from the structure of the isotypic compounds Mg₅Pd₁₀Si₁₆ and Mg₅Pt₁₀Si₁₆ by adding a Mg siteset and subtracting a platinum metal siteset. It can be described by an expanded cubic “close” packing of MgIr₆‐octahedra in which Si₄‐tetrahedra reside in the octahedral holes while Mg₄‐tetrahedra and MgSi₁₂‐units occupy one half of the tetrahedral holes each.     

Cs4BiAs3Se7: A Novel Bismuth‐Selenoarsenate with Infinite [BiAs3Se7]4– Chains Containing Two Different Anions, [AsSe3]3– and trans‐[As2Se4]4–

A new phase has been prepared by methanolothermal reaction of Cs₂CO₃, BiCl₃ and Li₃AsSe₃ at 130 °C for 36 hours. Cs₄BiAs₃Se₇ ( I ) reveals the first Bi‐selenoarsenate polyanionic chain [Bi(As₂Se₄)(AsSe₃)]^4–, consisting of Bi³⁺ ions in a distorted octahedral environment of [AsSe₃]^3– and trans‐[As₂Se₄]^4– units. The latter anion consists of a central “As₂⁴⁺” dumb‐bell whereby two Se atoms are attached to each of the As atoms. Structural Data: Space Group P2₁/n, a = 13.404(4) Å, b = 23.745(8) Å, c = 13.880(4) Å, β = 99.324(6)°, Z = 8.     

catena‐Poly­[[di­aqua­cadmium(II)]‐μ‐5‐carboxyimidazole‐4‐carboxylato‐κ4N1,O5:O4,N3]

A new cadmium coordination polymer, [Cd(C₅H₂N₂O₄)(H₂O)₂]_n, possesses a one‐dimensional zigzag chain structure built from Cd^II centers bridged sequentially by pairs of O and N atoms of the 5‐carboxyimidazole‐4‐carboxylate ligand. The Cd^II center is in a distorted octahedral geometry, being coordinated by two O atoms from two coordinated water mol­ecules [Cd—O = 2.322 (7) and 2.364 (7) Å], and by two N atoms [Cd—N = 2.222 (6) and 2.232 (6) Å] and two carboxyl O atoms [Cd—O = 2.383 (6) and 2.414 (6) Å] from two 5‐carboxyimidazole‐4‐carboxylate ligands.     

Ternäre Nickelphosphide und -arsenide mit einem Metall: Nichtmetall-Verhältnis von 2:1

Ternary Phosphides and Arsenides of Nickel with a Metal: Non-Metal Ratio of 2:1 Several new ternary phosphides and arsenides of nickel were prepared by reaction of the elements. SrNi₅P₃, SrNi₅As₃, and EuNi₅As₃ crystallize in the LaCo₅P₃ structure with the following lattice constants [Å]: BaNi₉P₅ (a = 6.534(1) Å, c = 10.847(2) Å) and BaNi₉As₅ (a = 6.760(1) Å, c = 11.226(2) Å) crystallize in a new type of structure (P6₃/mmc, Z = 2). The characteristic polyhedra are trigonal Ni-antiprisms centered by P or As atoms and trigonal Ni-prisms with vacant centres and sides capped by non-metal atoms. U₂Ni₁₂P₇ (a = 9.077(2) Å, c = 3.694(1) Å) has a Zr₂Fe₁₂P₇ structure (P6 , Z = 1).     

Kristall‐ und elektronische Strukturen von AIr2P2 (A: Ca — Ba)

Crystal and Electronic Structures of AIr₂P₂ (A: Ca — Ba) Single crystals of CaIr₂P₂ (a = 6.610(3), c = 7.031(3)Å) were prepared by reaction of the elements in a lead flux and investigated by X‐ray methods. The compound crystallizes with the EuIr₂P₂ type (P3₂21; Z = 3) just detected in the case of SrIr₂P₂. In the structure all the P atoms and half of the Ir atoms build a three‐dimensional framework with Ca and the remaining Ir atoms in the cavities. The latter atoms form threefold screws along [001] with relatively short Ir‐Ir distances and they are connected with the framework by Ir‐P bonds. LMTO band structure calculations suggested that the compounds with Ca, Sr, and Eu should be semiconductors. For EuIr₂P₂ this was confirmed by conductivity measurements. BaIr₂P₂ (a = 3.946(1), c = 12.572(2)Å) synthesized by heating the elements at 1050 °C for a long time crystallizes with the ThCr₂Si₂ type structure (I4/mmm; Z = 2). Due to the rigid layers of IrP₄ tetrahedra and the atomic size of barium the P‐P distance between the layers with a value of 3.71Å is very long.     

catena‐Poly­[[[cis‐bis(1‐phenyl­tetra­zole‐κN4)copper(II)]‐di‐μ‐chloro] hemi(1‐phenyl­tetrazole)]

The title compound, {[CuCl₂(PhTz)₂]·0.5PhTz}_n (PhTz is 1‐­phenyl­tetrazole, C₇H₆N₄), has a polymeric structure, with uncoordinated disordered PhTz mol­ecules in the cavities. The coordination polyhedron of the Cu atom is a highly elongated octahedron. The equatorial positions are occupied by two Cl atoms [Cu—Cl = 2.2687 (9) and 2.2803 (7) Å] and two N atoms of the PhTz ligands [Cu—N = 2.0131 (19) and 2.0317 (18) Å]. The more distant axial positions are occupied by two Cl atoms [Cu—Cl = 3.0307 (12) and 2.8768 (11) Å] that lie in the equatorial planes of two neighbouring Cu octahedra. The [CuCl₂(PhTz)₂] units are linked by Cu—Cl bridges into infinite chains extending parallel to the a axis. The chains are linked into two‐dimensional networks by intermolecular C—H⋯N interactions between the phenyl and tetrazole fragments, and by face‐to‐face π–π interactions between symmetry‐related phenyl rings. These two‐dimensional networks, which lie parallel to the ac plane, are connected by intermolecular π–π stacking interactions between phenyl rings, thus forming a three‐dimensional network.     

Stapelvarianten aus SrPtSb‐ und CaAl2Si2‐analogen Baublöcken

Stacking Variants of SrPtSb and CaAl₂Si₂ analogous Units Structure determinations on the basis of single crystal X‐ray methods revealed, that the crystal structures of Ca₃Cu₂Zn₂P₄ (P3 m1; Z = 1; a = 4.034(1), c = 14.604(3) Å), the isotypic Eu compound (a = 4.150(9), c = 15.210(7) Å), of Ca₂CuZn₂P₃ (P6₃/mmc; Z = 2; a = 4.048(2), c = 21.466(11) Å) and Ca₄Cu₃Zn₂P₅ (P6₃/mmc; Z = 2; a = 4.041(1), c = 37.060(7) Å) respectively can be described as stacking variants built up by two different segments. The first one corresponds with the hexagonal SrPtSb structure type, the second one with the trigonal CaAl₂Si₂ structure type. The segments along [001] are arranged one another and are represented with different weightiness in the compounds concerned.     

Rare‐Earth‐Rich Magnesium Compounds RE23Rh7Mg4 (RE = La,Ce, Pr,Nd, Sm,Gd) with Tetrahedral Mg4 Clusters

The rare earth‐rich compounds RE₂₃Rh₇Mg₄ (RE = La, Ce, Pr, Nd, Sm, Gd) were prepared by induction‐melting the elements in sealed tantalum tubes. The new compounds were characterized by X‐ray powder diffraction. They crystallize with the hexagonal Pr₂₃Ir₇Mg₄ type structure, space group P6₃mc. The structures of La₂₃Rh₇Mg₄ (a = 1019.1(1), c = 2303.7(4) pm, wR2 = 0.0827, 1979 F² values, 69 variables), Nd₂₃Rh₇Mg₄ (a = 995.4(2), c = 2242.3(5) pm, wR2 = 0.0592, 2555 F² values, 74 variables) and Gd₂₃Rh_6.86(5)Mg₄ (a = 980.5(2), c = 2205.9(5) pm, wR2 = 0.0390, 2083 F² values, 71 variables) were refined from single crystal X‐ray diffractometer data. The three crystallographically different rhodium atoms have trigonal prismatic rare earth coordination with short RE–Rh distances (283–300 pm in Nd₂₃Rh₇Mg₄). The prisms are condensed via common edges, leading to a rigid three‐dimensional network in which isolated Mg₄ tetrahedra (312–317 pm Mg–Mg in Nd₂₃Rh₇Mg₄) are embedded. Temperature dependent magnetic susceptibility data of Ce₂₃Rh₇Mg₄ indicate Curie‐Weiss behavior with an experimental magnetic moment of 2.52(1) μ_B/Ce atom, indicative for stable trivalent cerium. Antiferromagnetic ordering is evident at 2.9 K.     

Mg15Ir5Si2, ein Magnesium‐Iridiumsilicid mit isolierten Ir5Si2‐Baugruppen

Mg₁₅Ir₅Si₂ a Magnesium Iridium Silicide with Isolated Ir₅Si₂ Building Groups Mg₁₅Ir₅Si₂ (tetragonal, P4₂/n, a = 1371.7(1) pm, c = 873.0(2) pm, Z=4, 1497 reflections, 103 parameters, R1 = 0.048) was prepared by reaction of the elements at 900 °C in sealed tantalum ampoules. The compound is the silicide with the highest alkaline earth metal content known so far. It is the first example of a silicide with an isolated transition metal silicon building group embedded in a matrix of non‐transition metal atoms. The structure contains planar Ir₂SiIrSiIr₂ groups with silicon atoms in nearly trigonal planar coordination of three iridium atoms (d_Ir‐Si = 235 and 236 pm).     

Spatial Separation of Covalent,Ionic, and Metallic Interactions in Mg11Rh18B8 and Mg3Rh5B3

The crystal structures of Mg₁₁Rh₁₈B₈ and Mg₃Rh₅B₃ have been investigated by using single‐crystal X‐ray diffraction. Mg₁₁Rh₁₈B₈: space group P4/mbm; a=17.9949(7), c=2.9271(1) Å; Z=2. Mg₃Rh₅B₃: space group Pmma; a=8.450(2), b=2.8644(6), c=11.602(2) Å; Z=2. Both crystal structures are characterized by trigonal prismatic coordination of the boron atoms by rhodium atoms. The [BRh₆] trigonal prisms form arrangements with different connectivity patterns. Analysis of the chemical bonding by means of the electron‐localizability/electron‐density approach reveals covalent B? Rh interactions in these arrangements and the formation of B? Rh polyanions. The magnesium atoms that are located inside the polyanions interact ionically with their environment, whereas, in the structure parts, which are mainly formed by Mg and Rh atoms, multicenter (metallic) interactions are observed. Diamagnetic behavior and metallic electron transport of the Mg₁₁Rh₁₈B₈ and Mg₃Rh₅B₃ phases are in agreement with the bonding picture and the band structure.     

Darstellung und Kristallstrukturen von Ln2Al3Si2 und Ln2AlSi2 (Ln: Y,Tb–Lu)

Synthesis and Crystal Structures of Ln ₂Al₃Si₂ and Ln ₂AlSi₂ ( Ln : Y, Tb–Lu) Eight new ternary aluminium silicides were prepared by heating mixtures of the elements and investigated by means of single‐crystal X‐ray methods. Tb₂Al₃Si₂ (a = 10.197(2), b = 4.045(1), c = 6.614(2) Å, β = 101.11(2)°) and Dy₂Al₃Si₂ (a = 10.144(6), b = 4.028(3), c = 6.580(6) Å, β = 101.04(6)°) crystallize in the Y₂Al₃Si₂ type structure, which contains wavy layers of Al and Si atoms linked together by additional Al atoms and linear Si–Al–Si bonds. Through this there are channels along [010], which are filled by Tb and Dy atoms respectively. The silicides Ln₂AlSi₂ with Ln = Y (a = 8.663(2), b = 5.748(1), c = 4.050(1) Å), Ho (a = 8.578(2), b = 5.732(1), c = 4.022(1) Å), Er (a = 8.529(2), b = 5.719(2), c = 4.011(1) Å), Tm (a = 8.454(5), b = 5.737(2), c = 3.984(2) Å) and Lu (a = 8.416(2), b = 5.662(2), c = 4.001(1) Å) crystallize in the W₂CoB₂ type structure (Immm; Z = 2), whereas the structure of Yb₂AlSi₂ (a = 6.765(2), c = 4.226(1) Å; P4/mbm; Z = 2) corresponds to a ternary variant of the U₃Si₂ type structure. In all compounds the Si atoms are coordinated by trigonal prisms of metal atoms, which are connected by common faces so that Si₂ pairs (d_Si–Si: 2.37–2.42 Å) are formed.     

Die Cluster‐Salze Bi14Si2MI12 (M = Rh,Ir): [Bi8Si2]‐ und [MBi6I12]‐Baugruppen in CsCl‐analoger Anordnung

The Cluster Salts Bi₁₄Si₂MI₁₂ (M = Rh, Ir): [Bi₈Si₂] and [MBi₆I₁₂] Building Groups in CsCl‐like Structure The reaction of bismuth and iridium with iodine in evacuated quartz ampoules at 1320 K yields black, air insensitive crystals of Bi₁₄Si₂IrI₁₂. The silicon therein is abstracted from the ampoule material whereby the oxygen is gettered in BiOI. The synthesis of Bi₁₄Si₂RhI₁₂ requires the addition of niobium, which gives NbOI₂ with the oxygen originating from the SiO₂. X‐ray diffraction on single crystals showed that the two isotypic compounds crystallize in the space groups P 4/m c c with a = 1018.3(1), c = 2020.1(4) pm for M = Ir, and a = 1019.0(1), c = 2018.7(4) pm for M = Rh. The crystal structures consist of two types of isolated clusters, which form a CsCl‐like packing. In the [MBi₆I₁₂] cuboctahedron the central transition metal atom is octahedrally surrounded by bismuth atoms, and the iodine atoms bridge the edges of the octahedron. The [Bi₈Si₂] polyhedron is a tetragonal antiprism of bismuth atoms of which square faces are capped by silicon atoms. Based on crystal chemistry and band structure calculations the compounds may be formulated as cluster salts [Bi₈Si₂]³⁺[MBi₆I₁₂]^3–. Measurements of the electrical conductivity showed that Bi₁₄Si₂IrI₁₂ is a semiconductor with a band gap of about 0.1 eV. A single unpaired electron out of 1903 electrons per formula causes paramagnetic behaviour that is superposed by strong diamagnetic contributions.     

Di‐μ‐methanolato‐bis[(η4‐tetrafluorobenzobarrelene)rhodium(I)]

The versatile synthetic precursor methanolate‐bridged title rhodium complex, [Rh₂(CH₃O)₂(C₁₂H₆F₄)₂] or [Rh(μ‐OCH₃)(tfbb)]₂ [tfbb = tetrafluorobenzobarrelene or 3,4,5,6‐tetrafluorotricyclo[6.2.2.0^2,7]dodeca‐2(7),3,5,9,11‐pentaene], has been structurally characterized. The asymmetric unit contains half a molecule that can be expanded via a twofold axis. The title compound has been shown to be a dinuclear rhodium complex where each metal centre is coordinated by two O atoms from two bridging methanolate groups and by the olefinic bonds of a tfbb ligand. Comparison of the bite angles of tfbb, norbornadiene (nbd) and cyclooctadiene (cod) olefins in their η⁴‐coordination to rhodium reveals similarities between the tfbb and nbd ligands, which are much more rigid than cod. The short distance found between the distorted square‐planar metal centres [2.8351 (4) Å] has been related to the syn conformation of the folded core `RhORhO' ring.     

Hexa‐μ2‐chloro‐μ4‐oxo‐tetrakis[(2‐ethyl­tetrazole‐κN4)copper(II)]

In the title molecular complex, [Cu₄Cl₆O(2‐EtTz)₄], where 2‐EtTz is 2‐ethyl­tetrazole (C₃H₆N₄), the central O atom is located on the symmetry site and is tetrahedrally coordinated to four Cu atoms, with Cu—O distances of 1.8966 (4) Å. A very slight distortion of Cu₄O from a regular tetrahedron is observed [two Cu—O—Cu angles are 108.76 (3)° and four others are 109.828 (13)°]. Each Cu atom is connected to three others via the Cl atoms, forming a slightly distorted Cl octahedron around the O atom, with O⋯Cl distances of 2.9265 (7) Å for Cl atoms lying on the twofold axis and 2.9441 (13) Å for those in general positions. The Cu atom has a distorted trigonal–bipyramidal environment, with three Cl atoms in the equatorial plane, and with the N atom of the 2‐ethyl­tetrazole ligand and the μ₄‐O atom in axial positions. The Cu atom is displaced out of the equatorial plane by ca 0.91 Å towards the coordinated N atom of the 2‐­ethyl­tetrazole ligand.