La8Br7Ni4: ribbons of Ni hexagons in condensed La6 trigonal prisms

A ternary lanthanum bromide La 8Br 7Ni 4 was synthesized from La, LaBr 3, and Ni under an Ar atmosphere at 830 degrees C. It crystallizes in space group C2/ m (No. 12) with lattice constants a = 29.528(4) A, b = 4.0249(6), c = 8.708(1) A, and beta = 94.515(2) degrees . The structure features condensed Ni-centered La 6 trigonal prisms. The Ni atoms are bonded to each other to form ribbons of Ni hexagons. Band structure, bonding, and physical properties of the compound have been investigated.     

Hydrogen bonding in protonated water clusters: an atoms-in-molecules perspective

This article highlights the results of a detailed study of hydrogen bonding in the first and the second solvation shells of Eigen (H3O+) and Zundel (H5O2+) cations solvated by water in a stepwise manner. It is evident from the results that an electron density analysis clearly distinguishes the first and the second solvation shell and helps in quantifying the strength of hydrogen bonding in these clusters.     

La6Br10Fe: a La6Fe octahedron with a mixed M6X12/M6X8 type environment

The title compound was synthesized from La, LaBr3, and Fe under Ar atmosphere at 800 degrees C. It crystallizes in space group P4(1) (No. 76) with lattice constants a = 8.255(1) A and c = 30.033(6) A. The structure features an isolated Fe-centered La 6 octahedron with all corners, 9 of its 12 edges, and 3 of its 8 triangular faces coordinated, bridged, or capped by Br atoms. The La6Fe octahedron is significantly distorted, and the La coordination by Br atoms deviates from the common close-packing arrangements found in other reduced rare earth metal halides. Band structure, bonding, and physical properties of the compound have been investigated.     

Single-molecule magnets: novel Mn(8) and Mn(9) carboxylate clusters containing an unusual pentadentate ligand derived from pyridine-2,6-dimethanol

The reactions of the Mn(III)(3) and Mn(II)Mn(III)(2) complexes [Mn(3)O(O(2)CEt)(6)(py)(3)][ClO(4)] and [Mn(3)O(O(2)CEt)(6)(py)(3)] with pyridine-2,6-dimethanol (pdmH(2)) afford the mixed-valence Mn(II)(6)Mn(III)(2) octanuclear complex [Mn(8)O(2)(py)(4)(O(2)CEt)(8)(L)(2)][ClO(4)](2) (1) and the Mn(II)(7)Mn(III)(2) enneanuclear complex [Mn(9)(O(2)CEt)(12)(pdm)(pdmH)(2)(L)(2)] (2), respectively. Both compounds contain a novel pentadentate ligand, the dianion of (6-hydroxymethylpyridin-2-yl)-(6-hydroxymethylpyridin-2-ylmethoxy)methanol (LH(2)), which is the hemiacetal formed in situ from the Mn-assisted oxidation of pdmH(2). Complex 1 crystallizes in the monoclinic space group P2(1)/n with the following cell parameters at -160 degrees C: a = 16.6942(5) A, b = 13.8473(4) A, c = 20.0766(6) A, beta = 99.880(1) degrees, V = 4572.27 A(3), and Z = 2, R (R(w)) = 4.78 (5.25). Complex 2.0.2MeCN crystallizes in the triclinic space group Ponemacr; with the following cell parameters at -157 degrees C: a = 12.1312(4) A, b = 18.8481(6) A, c = 23.2600(7) A, alpha = 78.6887(8) degrees, beta = 77.9596(8) degrees, gamma = 82.3176(8) degrees, V = 5076.45 A(3), and Z = 2, R (R(w)) = 4.12 (4.03). Both complexes are new structural types comprising distorted-cubane units linked together, albeit in two very different ways. In addition, complex 2 features three distinct binding modes for the chelating ligands derived from deprotonated pdmH(2). Complexes 1 and 2 were characterized by variable-temperature ac and dc magnetic susceptibility measurements and found to possess spin ground states of 0 and 11/2, respectively. Least-squares fitting of the reduced magnetization data gave S = 11/2, g = 2.0, and D = -0.11 cm(-1) for complex 2, where D is the axial zero-field splitting parameter. Direct current magnetization versus field studies on 2 at <1 K show hysteresis behavior at <0.3 K, establishing 2 as a new single-molecule magnet. Magnetization decay measurements gave an effective barrier to magnetization relaxation of U(eff) = 3.1 cm(-1) = 4.5 K.     

Structure-directing effects in the supramolecular intercluster compound [Au9(PPh3)8]2[V10O28H3]2: long-range versus short-range bonding interactions

Although being composed of trivalent ions, the crystal structure of the supramolecular intercluster compound [Au9(PPh3)8]2[V10O28H3]2 is dominated by short-range intermolecular interactions, i.e., hydrogen bonds, and C-H/pi interactions, avoiding a simple AB-type packing.     

Synthesis, structure, and bonding of BaTl(3): an unusual competition between cluster and classical bonding in the thallium layers.

The new BaTl(3) compound has been synthesized and characterized by physical property measurements and electronic structure calculations. Its structure (Cmcm) is a new intermediate in the Ni(3)Sn family (P6(3)/mmc), and consists of thallium layers formed from two-center bond formation between the parallel chains of face-sharing octahedral clusters. The valence electron concentration (VEC) of the thallium layers is consistent with their two-dimensional nature, in comparison with those in other AX(3)-type compounds with one- or three-dimensional anionic networks with the same building blocks and different VECs. The unique geometric features of the anionic thallium layers bring on an unusual competition between inter- and intracluster bonds. Detailed studies of the energetics of BaTl(3) reveal for the first time the important role of cation-anion interactions in the bonding competition in such an anionic substructure.     

The heteronuclear bonding between heavier Group 14 elements and transition metals: a novel trioxystannate-iron complex with an unusual stannate fragment

A new trioxystannate-transition metal complex, {[Li][(Me(2)NCH(2)CH(2)O)(3)Sn-Fe(CO)(4)]}(2) (3), exhibiting an unusual type of the heteronuclear bonding between heavier Group 14 elements and transition metals, has been synthesised and completely characterised by NMR, Raman and IR spectroscopy in solution as well as by Raman spectroscopy and X-ray diffraction analysis in the solid state.     

Al14Ba8La26.3Ru18Sr53.7O167: a variant of cubic perovskite with isolated RuO6 units

The crystal structure of the title aluminium barium lanthanum ruthenium strontium oxide has been solved and refined using neutron powder diffraction to establish the parameters of the oxygen sublattice and then single‐crystal X‐ray diffraction data for the final refinement. The structure is a cubic modification of the perovskite ABO₃ structure type. The refined composition is Ba_0.167La_0.548Sr_1.118Ru_0.377Al_0.290O_3.480, and with respect to the basic perovskite structure type it might be written as (Ba₈La_13.68Sr_34.32)(Al_13.92La_12.64Ru_18.08Sr_19.36)O_192−x, with x = 24.96. The metal atoms lie on special positions. The A‐type sites are occupied by Ba, La and Sr. The Ba atoms are located in a regular cuboctahedral environment, whereas the La and Sr atoms share the same positions with an irregular coordination of O atoms. The B‐type sites are divided between two different Wyckoff positions occupied by Ru/Al and La/Sr. Only Al and Ru occupy sites close to the ideal perovskite positions, while La and Sr move away from these positions toward the (111) planes with high Al content. The structure contains isolated RuO₆ octahedra, which form tetrahedral substructural units.     

Zr(11)Sb(18): a new binary antimonide exhibiting an unusual Sb atom network with nonclassical Sb-Sb bonding

The herewith-introduced antimonides Zr(11)Sb(18) and Zr(10.4)V(0.6)Sb(18) were prepared by high-temperature techniques; both arc-melting and solid-state reactions at 1200 degrees C starting from alpha-ZrSb(2) and the metals Zr and V in powder form are possible methods. These isostructural compounds represent an unprecedented metal:antimony ratio of 11:18 and form a new structure type. Zr(11)Sb(18) crystallizes in the tetragonal space group I(-)42d, with the lattice dimensions a = 676.94(4) pm and c = 6007.3(5) pm, while the V-containing phase forms a slightly smaller unit cell with a = 676.48(8) pm and c = 6005.6(9) pm (Z = 4). Their structures are comprised of an Sb atom substructure with several intermediate Sb-Sb bonds starting at 311 pm, which is reminiscent of that found in the series (Ti,M)(5)Sb(8) (M = Zr, Hf, Nb, Mo) published last year. Interwoven with this network is the Zr atom network, which forms a diamond-like metal atom substructure with long Zr-Zr contacts of ca. 360 pm. Band structure calculations based on the linear muffin tin orbital approach reveal these antimonides to be mainly stabilized by strong M-Sb and intermediate Sb-Sb bonds, and additionally--to the smallest extent--by M-M bonds (M = Zr, V). In agreement with the electronic structure calculations, Zr(11)Sb(18) is metallic with a small positive Seebeck coefficient.     

La2XB3 (X = Cl,Br): A Novel Layered Structure with Planar Boron Nets of B3, B6 and B8 Rings

Two new layered rare earth boride halides, La₂XB₃ (X = Cl, Br) have been synthesized. They crystallize in the space group (No. 174) with a = 7.872(1) Å, c = 8.219(2) Å, V = 441.1(1) ų for the chloride, and with a = 7.834(1) Å, c = 8.440(1) Å, V = 448.6(1) ų for the bromide compound, respectively. The crystals of La₂ClB₃ are twinned resulting in an apparent symmetry P6/mmm (No. 191). In the crystal structure of La₂XB₃, trigonal La₆ prisms are condensed into sheets in the a‐b plane, and the halogen atoms X sandwich the La double layers. The connection of B atoms which center the prisms and rectangular prism faces leads to B nets of B₃, B₆ and B₈ rings embedded between the La atom double layers. The chemical bonding is analyzed for the well ordered bromide, and the characteristic disorder in the chloride is discussed.     

Synthesis, structure, and bonding of open-shell Sr3In5: an unusual electron deficiency in an indium network, beyond the Zintl boundary.

The new title compound has been synthesized and characterized by physical property measurements and electronic structure calculations. The results ratify the highly uncommon deficiency of one electron that has been long speculated for its Ca3Ga5-type structure on the basis of the simple Zintl electron counting formalism. In the Sr3In5 structure (Cmcm), 4- and 2-bonded indium atoms in a 4:1 ratio form a three-dimensional classical network that encapsulates strontium atoms in its narrow channels. The electrical conductivity of the compound shows typical metallic behavior. The detailed electronic structure analysis suggests that the electron hole is mainly localized on a nonbonding p-orbital on the 2-bonded indium atoms, and that these orbitals, stacked in a sigma-type way along avector (4.97 A), interact only weakly with each other to form highly one-dimensional bands.     

Halogen bonding to a divalent sulfur atom: an experimental study of the interactions of CF3X (X = Cl, Br, I) with dimethyl sulfide

Using FTIR and Raman spectroscopy, the formation of halogen bonded complexes of the trifluorohalomethanes CF(3)Cl, CF(3)Br and CF(3)I with dimethyl sulfide (DMS) dissolved in liquid krypton has been investigated. For CF(3)Br and CF(3)I, evidence was found for the formation of C-XS halogen bonded 1:1 complexes. At higher concentrations of CF(3)I weak absorptions due to a 2:1 complex were also observed. Using spectra recorded at temperatures between 118 and 163 K, the complexation enthalpies for the complexes were determined to be -9.5(5) kJ mol(-1) for CF(3)Br·DMS, -17.4(1) kJ mol(-1) for CF(3)I·DMS and -30.8(16) kJ mol(-1) for (CF(3)I·)(2)DMS. The results from the cryospectroscopic study are compared with ab initio calculations at the MP2/aug-cc-pVDZ(-PP) level. Apart from vibrational modes localized in the trifluorohalomethanes and the DMS moieties, for both CF(3)Br and CF(3)I, an additional band, which we assign as the intermolecular stretching mode in the complex, was identified in the infrared and Raman spectra.     

Halogen vs. ionic bonding: an unusual isomorphism between the neutral (C5Me5)2Fe/C2I2 cocrystal and ionic [(C5Me5)2Fe]Br3 crystal

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Zr2Ir6B with an eightfold superstructure of the cubic perovskite-like boride ZrIr3B0.5: Synthesis, crystal structure and bonding analysis

Single phase powder samples and single crystals of Zr₂Ir₆B were successfully synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere. Superstructure reflections were observed both on powder and on single crystal diffraction data, leading to an eightfold superstructure of ZrIr₃B_x phase. The new phase, which has a metallic luster, crystallizes in space group (no. 225) with the lattice parameters a=7.9903(4) Å, V=510.14(4) Å³. Its crystal structure was refined on the basis of powder as well as single crystal data. The single crystal refinement converged to R₁=0.0239 and wR₂=0.0624 for all 88 unique reflections and 6 parameters. Zr₂Ir₆B is isotypic to Ti₂Rh₆B and its structure can be described as a defect double perovskite, A₂BB′O₆, where the A site is occupied by zirconium, the B site by boron, the O site by iridium but the B′ site is vacant, leading to the formation of empty and boron-filled octahedral Ir₆ clusters. According to the result of tight-binding electronic structure calculations, Ir-B and Ir-Zr interactions are mainly responsible for the structural stability of the phase. According to COHP bonding analysis, the strongest bonding occurs for the Ir-B contacts, and the Ir-Ir bonding within the empty clusters is two times stronger than that in the BIr₆ octahedra.     

Syntheses, structure, and bonding of Rb14(Mg1-xInx)30. A nonstoichiometric phase with an unusual substitution in the anion framework

The title compound Rb(14)(Mg(1-x)In(x))(30) (x = 0.79-0.88) has been obtained from high-temperature reactions of the elements in welded Ta tubes. There is no analogous binary compound without Mg. The crystal structure established by single-crystal X-ray diffraction means (space group P2m (No. 189), Z = 1 and a = b = 10.1593(3) Angstroms, c = 17.783(1) Angstroms for x = 0.851) features two distinct types of anionic layers: isolated pentacapped trigonal prismatic In(11)(7-) clusters and condensed [(Mg(x)In(1-x))(5)In(14)](7-) layers. The latter consists of analogous M(11) (M = Mg/In) fragments that share prismatic edges and are interbridged by trigonal M(3) units. The structure shows substantial differences from related A(15)Tl(27) (A = Rb, Cs) in which the cation A that centers a six-membered ring of Tl(11) fragments is replaced by M(3.) Both linear muffin-tin orbital and extended Hückel calculations are used to analyze the observed phase width and site preferences. We further utilize the results to rationalize the distortion of the M(11) fragment in the condensed layer and also to correlate with electrical properties. An isomorphous phase region (Rb(y)K(1-)(y))(14)(Mg(1-x)In(x))(30) (y = 0.52, 0.66 for x = 0.79) is also formed.     

Metal-metal bonding in molecular actinide compounds: electronic structure of [M2X8](2-) (M = U, Np, Pu; X = Cl, Br, I) complexes and comparison with d-block analogues

Density functional and multiconfigurational (ab initio) calculations have been performed on [M(2)X(8)](2-) (X = Cl, Br, I) complexes of 4d (Mo, Tc, Ru), 5d (W, Re, Os), and 5f (U, Np, Pu) metals in order to investigate general trends, similarities and differences in the electronic structure and metal-metal bonding between f-block and d-block elements. Multiple metal-metal bonds consisting of a combination of sigma and pi interactions have been found in all species investigated, with delta-like interactions also occurring in the complexes of Tc, Re, Np, Ru, Os, and Pu. The molecular orbital analysis indicates that these metal-metal interactions possess predominantly d(z2) (sigma), d(xz) and d(yz) (pi), or d(xy) and d(x2-y2) (delta) character in the d-block species, and f(z3) (sigma), f(z2x) and f(z2y) (pi), or f(xyz) and f(z) (delta) character in the actinide systems. In the latter, all three (sigma, pi, delta) types of interaction exhibit bonding character, irrespective of whether the molecular symmetry is D(4h) or D(4d). By contrast, although the nature and properties of the sigma and pi bonds are largely similar for the D(4h) and D(4d) forms of the d-block complexes, the two most relevant metal-metal delta-like orbitals occur as a bonding and antibonding combination in D(4h) symmetry but as a nonbonding level in D(4d) symmetry. Multiconfigurational calculations have been performed on a subset of the actinide complexes, and show that a single electronic configuration plays a dominant role and corresponds to the lowest-energy configuration obtained using density functional theory.     

Sn12O8(OH)4(OEt)28(HOEt)4: an additional member in the family of dodecameric oxo clusters

A tin(IV) oxoalkoxo cluster with unprecedented architecture has been prepared and characterized by single-crystal X-ray diffraction. The cluster obeys the formula Sn 12O 8(OH) 4(OEt) 28(HOEt) 4 (1) and is based on an elongated centrosymmetric assembly of 12 six-coordinate tin centers, 28 peripheral ethoxy groups (terminal and bridging), 8 oxo bridges (mu2 and mu3), 4 hydroxy bridges (mu2), and 4 ethanol molecules that are all bound to tin atoms and interact strongly, through hydrogen bonds, with an ethoxy group located on a vicinal tin atom. This compound has also been fully characterized in solution by multinuclear 1D and 2D NMR, with all of its (119)Sn, (1)H, and (13)C NMR resonances assigned with respect to the structure. Altogether, the data allowed unambiguous location of the hydroxy groups. Information on the exchange of the ethoxy groups is also presented.     

Antiaromaticity in bare deltahedral silicon clusters satisfying Wade's and Hirsch's rules: an apparent correlation of antiaromaticity with high symmetry

Entirely unlike the aromatic closo BnHn2- borane dianions, isoelectronic Si62- and Si122- are antiaromatic. Their Oh and Ih symmetries are responsible, as the other deltahedral silicon dianion clusters do not exhibit this behavior. These high symmetries prevent mixing among the degenerate lone pair and skeletal orbitals, leading to paratropic behavior.