Synthesis and structural characterization of heavier group 1 methyl tetrazolate complexes: New bridging coordination modes of the tetrazolate ligand

A series of sodium, potassium, rubidium, and cesium complexes of methyl tetrazolate was prepared and structurally characterized. Treatment of methyl tetrazole (MetetzH) with the group 1 hydroxides in water at ambient temperature afforded Na(Metetz)(H₂O)₂ (92%), K(Metetz) (92%), Rb(Metetz) (97%), and Cs(Metetz) (97%) as colorless solids after workup. These complexes were characterized by spectral and analytical methods, thermogravimetric analysis, and by X-ray crystallography. Na(Metetz)(H₂O)₂ adopts a structure that consists of approximately octahedrally coordinated sodium ions that form infinite chains built up by two μ₂-aqua ligands and two μ₂-N₁,N₂-tetrazolate ligands between each sodium atom. The aqua ligand hydrogen atoms engage in hydrogen bonding with uncoordinated nitrogen atoms to hold the chains together. K(Metetz) and Rb(Metetz) are isostructural, with eight-coordinate metal ions and two metal–nitrogen bonds per nitrogen atom in each Metetz ligand. Cs(Metetz) has 10-coordinate cesium ions with two cesium–nitrogen bonds to two of the Metetz ligand nitrogen atoms and three cesium–nitrogen bonds to the other two nitrogen atoms. K(Metetz), Rb(Metetz), and Cs(Metetz) exhibit new coordination modes for the tetrazolate ligand.     

The unexpected decarbonylation of a molybdenum(O) dithiocarbamate and the formation of a molybdenum(V) dimeric product: Crystal structure of di-μ-sulfido-bis[oxo(pyrrolidinedithiocarbamato)molybdenum(V)]

The interaction of molybdenum hexacarbonyl with ammonium pyrrolidinedithiocarbamate in warm dimethylsulfoxide solution gives not the expected complex [NH₄][Mo(CO)₄(S₂CN(CH₂)₄)] but the molybdenum(V) dimer, di-μ-sulfido-bis[oxo(pyrrolidinedithiocarbamato)molybdenum(V)]. The structure of this oxidized product [MoO(S₂CN(CH₂)₄)S]₂ (1) was determined by single-crystal X-ray diffraction analysis. The crystals are triclinic, space group P$\text{I}$ with two molecules in a unit cell of dimensions a = 8.775(1), b = 16.592(2), c = 6.661(1) Å, α = 97.67(1), β = 97.89, γ = 80.23(1)°. The structure was solved by the heavy-atom method and refined by block-diagonal least-squares calculations to R = 0.037 for 3772 observed data. In the binuclear complex the two Mo atoms are bridged via two S atoms [Mo-S 2.303-2.317(1) Å]. Each Mo atom is also coordinated by a terminal O atom [1.688(4) and 1.682(4) Å] and two S atoms from the bidentate ligand [Mo-S 2.455-2.475(1) Å]. The geometry around the metal atoms is distorted square pyramidal.     

Structure and antiferroelectric properties of cesium niobate, Cs2Nb4O11

The compound cesium niobate, Cs₂Nb₄O₁₁, is an antiferroelectric, as demonstrated by double hysteresis loops in the electric field versus polarization plot. The crystal structure refinement by X-ray diffraction at both 100 and 297 K shows it to have a centrosymmetric structure in point group mmm and orthorhombic space group Pnna, which is consistent with its antiferroelectric behavior. The 100-K structure data is reported herein. The lattice is comprised of niobium-centered tetrahedra and octahedra connected through shared vertices and edges; cesium atoms occupy channels afforded by the three-dimensional polyhedral network. Antiferroelectricity is produced by antiparallel displacements of niobium atoms along the c-axis at the phase transition temperature of 165 °C. The critical field for onset of ferroelectric behavior in a single-crystal sample is 9.5 kV/cm at room temperature.     

Kentuckia: A 4,6,8-connected tetragonal structural pattern in space group P4/nmm

The crystal structure of a novel, hypothetical 4,6,8-connected tetragonal structural pattern with the ternary stoichiometry ABC ₂ is described. The novel pattern belongs to the P4/nmm space group (no. 129). It possesses the Wells point symbol (4⁴(4¹²6¹²)(4¹²)₂ and has the Wellsean Schläfli index (4.4615, 6). The new structural type may be represented by ternary bimetallic oxide in which two oxygen atoms within the unit cell adopt octahedral coordination with respect to two different metal atoms. A probable composition is CaPtO₂.     

An optically pumped,highly polarized cesium beam for the study of spin-dependent electron scattering

We have set up an atomic beam of cesium for the study of spin-dependent electron-cesium scattering. The beam is produced by an effusive oven with continuous recirculation of the condensed metal. The beam is optically pumped by circularly polarized light from two laser diodes tuned to the 6² S _1/2(F=3)→6² P _3/2(F′=4) and 6² S _1/2(F=4)→6² P _3/2(F′=5) transitions, respectively. Nearly all atoms are transferred into theF=4,m _F =+4 orm _F =?4 Zeeman level of the ground state, depending on the sense of circular polarization of the pumping light. The population distribution in the optically pumped beam is analyzed in terms of them _J =?1/2 andm _J =+1/2 components with a Stern-Gerlach magnet. We find the atomic polarization to be very close to unity at a density of 8×10⁸ atoms/cm³ in the scattering center. The polarization decreases slightly with increasing density of the cesium beam due to radiation trapping. A spin flipper serves as a means of polarization reversal, introducing no systematic errors in the spin asymmetry measurements. Lock-in technique is used to stabilize the atomic beam polarization by detecting fluorescence light signals.     

Synthesis and crystal structure of cyclopentadienyl(1,4-dimethyl-1,4-dibora-2,5-cyclohexadiene)cobalt

The synthesis of the organometallic derivative cyclopentadienyl(1,4-dimethyl-1,4-diboracyclohexa-2,5-diene)cobalt is described. This complex, [(CH₃BC₄H₄BCH₃)Co(η-C₅H₅)], forms red-oranged monoclinic crystals, space group P2₁/a with Z = 4 in a unit cell of dimensions a 11.362(7), b, 7.467(7), c 13.290(12) Å, β 103.76(6)°. The structure has been elucidated by heavy-atom methods from 1732 reflections (I > 2σ(I)) measured on a Syntex P2₁ four-circle diffractometer and refined to R = 0.055. In the coordination complex all six atoms of the cyclohexadiene ring are within bonding distance of the metal atom, but the two boron atoms bend away from the metal atom, and the ring elongates slightly in the B---B direction. As a standard of comparison the known geometry of the free ligand [1,4-difluoro-1,4-dibora-2,3,5,6-tetramethylcyclohexa-2,5-diene] is used. The terminal methyl groups on the boron atoms, by contrast, bend slightly back towards the metal atom. The cyclopentadienyl ring remains planar but is positionally disordered.     

Au2PbP2, Au2TlP2, and Au2HgP2: Ternary Gold Polyphosphides with Lead, Thallium, and Mercury in the Oxidation State Zero

The polyphosphide Au₂PbP₂ was prepared by reaction of the elemental components using liquid lead as a reaction medium. Well-developed crystals were obtained after dissolving the matrix in hydrochloric acid. Their crystal structure was determined from four-circle X-ray diffractometer data: Cmcm, a=323.6(1) pm, b=1137.1(2) pm, c=1121.8(1) pm, Z=4, R=0.023 for 478 structure factors and 20 variable parameters. The structure contains zigzag chains of phosphorus atoms with a typical single-bond distance of 219.4(2) pm. The two different kinds of gold atoms are both in linear phosphorus coordination with typical single-bond distances of 232.6(2) and 234.2(2) pm, and the lead atoms have only metal neighbors (7 Au and 2 Pb). Accordingly, chemical bonding of the compound may be expressed by the formula (Au⁺¹)₂Pb^±0(P⁻¹)₂. The corresponding thallium and mercury polyphosphides Au₂TlP₂ (a=324.1(1) pm, b=1136.1(1) pm, c=1122.1(1) pm) and Au₂HgP₂ (a=322.1(1) pm, b=1131.4(2) pm, c=1122.6(1) pm) were found to be almost isotypic with Au₂PbP₂. Their crystal structures were refined from single-crystal X-ray data to R=0.036 (682 F values, 25 variables) and R=0.026 (539 F values, 35 variables), respectively. The structure of these compounds may also be described as consisting of a three-dimensional network of condensed 8- and 10-membered Au₂P₆ and Au₄P₆ rings forming parallel channels, which are filled by the lead, thallium, and mercury atoms. The lead atoms are well localized in these channels, while the thallium and even more the mercury atoms occupy additional positions within these channels. Freshly prepared samples of Au₂HgP₂ show reproducibly slightly different axial ratios and larger cell volumes (ΔV=0.5%) than those after exposure of the samples to air for several days.     

Über die Synthese von Tris(trimethylsilyl)silyl-kalium, -rubidium und -caesium und die Molekülstrukturen zweier Toluolsolvate

About the Synthesis of Tris(trimethylsilyl)silyl Potassium, Rubidium and Cesium and the Molecular Structures of two Toluene Solvates . Solventfree tris(trimethylsilyl)silyl potassium ( 1 ), rubidium ( 2 ) and cesium ( 3 ) are obtained by the reaction of the zink group bis[tris(trimethylsilyl)silyl] derivatives with the appropriate alkali metal in n-pentane. Addition of benzene or toluene to the colourless powders yields deeply coloured solutions. From these solutions single crystals of tris(trimethylsilyl)silyl rubidium—toluene (2/1) ( 2 a ) and tris(trimethylsilyl)silyl cesium—toluene (2/3) ( 3 a ) suitable for X-ray structure analysis are iso- lated [ 2a : orthorhombic; P2₁2₁2₁; a = 1 382.1(3); b = 1 491.7(5); c = 2 106.3(6) pm; Z = 4 (dimers); 3a : orthorhombic; P2₁2₁2₁; a = 2 131.0(6); b = 2 833.1(2); c = 925.2(2) pm; Z = 4 (dimers)]. The central structure moieties are folded four-membered Rb₂Si₂ and Cs₂Si₂ rings, respectively. Small Si? Si? Si angles (100 to 104°) on the one hand and extreme highfield ²⁹Si-NMR shifts of the central silicon atoms on the other hand indicate a strong charge transfer from the alkali metal atoms to the tris(trimethylsilyl)silyl fragments, i.e. mainly ionic interactions between alkalimetal and silicon atoms.     

The chemical identity of “[Ag(py)2]MnO4” organic solvent soluble oxidizing agent and new synthetic routes for the preparation of [Ag(py)n]XO4 (X = Mn,Cl, and Re,n = 2–4) complexes

Abstract

A widely used oxidizing agent in organic chemistry with an assumed structure of “[Ag(py)₂]MnO₄” and its perchlorate and perrhenate analogues are studied. Their synthesis in pure form is challenging. In order to clarify the chemical nature of the known compounds and find routes to new derivatives, a systematic study is presented for the synthesis of [Ag(py)_n]XO₄ (X?=?Mn, Cl, and Re, n?=?2–4) complexes. Ten complexes including four new derivatives, [Ag(py)₄]MnO₄, [Ag(py)₄]MnO₄·4[Ag(py)₂]MnO₄, [Ag(py)₂]ClO₄·0.5 py, and [Ag(py)₂]ReO₄, are synthesized and characterized. The chemical identity of “Ag(py)₂MnO₄” is also clarified. A novel route to prepare [Ag(py)₂]MnO₄ is developed. The reaction of AgXO₄ salts with neat pyridine followed by various crystallization techniques is used to prepare [Ag(py)₂]XO₄, [Ag(py)₄]XO₄, [Ag(py)₄]XO₄·4[Ag(py)₂]XO₄, and [Ag(py)₂]XO₄·0.5py (X?=?Cl, Mn) complexes. The solid phase structure of [Ag(py)₂]MnO₄·0.5py is determined (a?=?19.410 Å, b?=?7.788 Å, c?=?21.177 Å, β?=?104.20°, C2/c (15), Z?=?4 (3a)). [Ag(py)₂]⁺ cations in the crystal form dimeric units where silver ions are connected by oxygen atoms of two MnO₄^– anions. The Ag…Ag distance is indicative of argentophilic interactions. The pyridine ring π…π interactions contribute to the stability of the crystal lattice.     

Structural refinements of praseodymium and neodymium orthophosphate

The crystal structures of PrPO₄ and NdPO₄ have been determined by single crystal X-ray diffraction techniques. The structures are isostructural with CePO₄ and LaPO₄, and are monoclinic in space group $\text{P2}{}_1\text{n}$. The cell constants are a = 6.741(3), b = 6.961(4), c = 6.416(3) Å, and β = 103.63(3)° for PrPO₄ and a = 6.722(1), b = 6.933(1), c = 6.390(2) Å, and β = 103.72(2)° for NdPO₄. The least-squares structural refinements of PrPO₄ and NdPO₄ yielded R values of 0.034 and 0.038 based on 810 and 947 unique reflections, respectively. The lanthanide metal atoms are coordinated with nine oxygens and are linked together by very slightly distorted tetrahedral phosphate groups. The nine oxygen atoms ligating the lanthanide atoms form a polyhedron that is best described as a pentagonal interpenetrating tetrahedron.     

Cs2B2S4 – Ein Salz der dimeren Metathioborsäure

Cs₂B₂S₄ – A Derivative of the Dimeric Metathioboric Acid Cs₂B₂S₄ (structure: I4₁/acd; a = 7.270(1) Å, c = 35.737(7) Å; Z = 8; substructure: I4/mmm; a′ = 5.141(1) Å, c′ = 17.868(4) Å, Z = 2) is prepared by the reaction of cesium sulfide with stoichiometric amounts of boron and sulfur (effective molar ratio M:B:S = 2:2:4) at 600°C and subsequent annealing. The crystal structure contains isolated [B₂S₄]^2? groups consisting of four-membered B₂S₂ rings with two exocyclic sulfur atoms on each of the boron atoms. The cesium cations are nine-coordinate between these rings. The structural feature of two edge-sharing BS₃ groups forming an isolated anion appears for the first time in thioborate chemistry, although it is known as a part of the polymeric network in B₂S₃.     

X-ray crystal structure of azoxybenzene oxotetrachlorotungsten(VI), (C6H5N)2OWVIOCl4

The crystal and molecular structure of azoxybenzene oxotetrachlorotungsten(VI) has been determined from X-ray diffractometer data. The structure was solved by Patterson and Fourier methods and refined by least-squares techniques to R = 0.058 for 1869 independent reflections.The crystals are monoclinic, space group P2₁/c, with Z = 4, in a unit cell of dimensions: a = 8.314(3), b = 15.100(5), c = 12.901(7) Å, α = 95.31(5)°. The azoxybenzene residue, the structure of which resembles that of free trans azobenzene, is linked to the tungsten atom through its oxygen atom. The coordination at the metal (two oxygen atoms and four chlorine atoms) corresponds to a distorted octahedron.This distortion is very similar to those observed in similar tungsten compounds. There is a intramolecular C?O distance of 2.77 Å between two atoms four bonds apart, of the azoxybenzene residue.     

The crystal and molecular structure of the tetraethylammonium salt of tetrahydridopentadecacarbonyltetrarhenate(2−) in two crystallographic forms

The structure of the title compound, (NEt₄)₂[H₄Re₄(CO)₁₅], is reported in two crystallographic modifications, I and II. Both forms axe monoclinic and the cell constants are as follows: I, a 11.355(2), b 21.204(4), c 17.416(3) Å, β 94.15(2)°, space group P2₁/c; II, a 21.831(4), b 17.584(3), c 11.446(2) Å, β 96.02(2)°, space group P2₁,/n. Two sets of 3042 (I) and 2870 (II) independent diffraction intensities, collected by counter methods, were used for the solution and refinement of the two structures. The final conventional R factors have values 5.5% (I) and 6.3% (II), respectively. The crystal packings are compared, showing different conformations of the (NEt₄)⁺ cations. The anions contain a tetrametal cluster formed by an isosceles triangle plus an apically bound metal atom; the carbonyl groups are all terminally bonded to the rhenium atoms. Some differences, present both in the metal atom clusters and in the carbonyl dispositions, are discussed and compared with a third, previously reported, crystallographic modification of the same compound.     

Preparation and x-ray crystal structure of racemic bis(ethylfumarate)bis(acetonitrile)cobalt(0)

The preparation and properties of some new tetracoordinated cobalt(0) complexes containing nitrile and fumaric ester ligands are described. One of them, Co(C₂H₅OOCCHCHCOOC₂H₅)₂(CH₃CN)₂, (la), reacts with 1,10-phenanthroline to give new pentacoordinated and hexacoordinated cobalt(0) complexes.The structure of Ia has been determined from X-ray diffractometer data. The structure was solved by Patterson and Fourier methods and refined by least square techniques to R  0.060 for 2215 independent reflections. Crystals are triclinic, space group P$\text{1}$, with Z  2 in a unit cell of dimensions: a 14.794(18), b 9.448(11), c 10.125(12) Å, α 108.55(9), β 111.42(11), γ 84.95(18)°. The metal is linked to the four carbon atoms of the CHCH groups of the ethyl fumarate residues and to the nitrogen atoms of the two acetonitrile ligands. The coordination of the four ligands around the cobalt atom corresponds to a distorted trigonal pyramid. The four asymmetric carbon atoms of a molecule have the same absolute configuration. RRRR and SSSS molecules are present in the unit cell.     

Isomerism and Vibration Spectra of M2XO4 Molecules (M = Li,Na, K; X = S,Se, Te,Cr, Mo,W)

The equilibrium geometries, isomerization energies, force fields, vibration frequencies, and band intensities in the IR spectra of M₂XO₄ molecules (M = Li, Na, K; X = S, Se, Te, Cr, Mo, W) were calculated ab initio by the Hartree-Fock method in extended basis sets using relativistic effective core potentials. The relative energies of alternative structures were refined by the configuration interaction method taking into account single- and double-excited configurations, with the Davidson correction for quartic excitations. The results show that the chemical bonds between the metal atom and the acid residue XO₄ are highly polar. The majority of M₂XO₄ molecules have two isomers. In both isomers the XO₄ ^{2 -} anion coordinates the metal cations M⁺ in the bisbidentate (bb) fashion. The equilibrium configurations ofthe nuclei in the ground (bb) and excited (bb') isomers have the D ₂ d and C _s symmetry, respectively. In the bb isomer, the cations coordinate at the opposite, and in the bb' isomer, at the adjacent edges of the XO₄ ^{2 -} anion, having the shape of a distorted tetrahedron. The relative energy of the bb' isomer is 9-28 kJ mol^{- 1}. The energy barriers to intramolecular rearrangements bb'(C _4s) bb(D _{2 d}) are also low: 15-35 kJ mol^{- 1}. These results show that the M₂XO₄ molecules are structurally nonrigid, with a polytopic character of the M-XO₄ chemical bonds. The calculation results were compared to the published experimental data on the structure and vibration spectra of the M₂XO₄ molecules.     

The crystal structure of U5Re3C8

U₅Re₃C₈ crystallizes tetragonal in space group P4/mbm with the lattice constantsa=1 131.3(1) pm,c=330.29(7) pm,V=0.4227 nm³ andZ=2 formula units per cell. The structure was determined from single-crystal counter-data and refined to a residual ofR=0.032 for 649 structure factors and 24 variable parameters. It is of a new type with carbon atoms on three different sites with approximately octahedral environment of five uranium and one rhenium or four uranium and two rhenium atoms. The positions of the metal atoms correspond to those of a (slightly distorted) cubic body centered structure as is also found for Ho₂Cr₂C₃, UCr₄C₄, UMoC₂, YCoC, and U₂IrC₂.     

Alkalimetall‐Phosphaniminate. Neue Synthesen und die Kristallstrukturen von [RbNPPh3]6 und [CsNPPh3]4

Alkali Metal Phosphoraneiminates. New Syntheses and Crystal Structures of [RbNPPh₃]₆ and [CsNPPh₃]₄ The alkali‐metal phosphoraneiminates MNPPh₃ with M = Na, K, Rb, Cs have been synthesized by reactions of Ph₃PI₂ with the alkali‐metal amides in liquid ammonia and were obtained as pure samples by subsequent extraction with toluene. The ethyl derivative KNPEt₃ has been prepared by an analogous route from Et₃PBr₂ and extraction with hexane. Single crystals of the phosphoraneiminates of rubidium and cesium are obtainable by crystallization from toluene and toluene/hexane, respectively. They were suitable for crystal structure determinations. [RbNPPh₃]₆ · 4¹/₂ toluene ( 1 ): space group P1, Z = 2, lattice dimensions at 193 K: a = 1525.5(2); b = 1902.9(2); c = 2178.3(2) pm; α = 95.435(12)°; β = 91.145(12)°; γ = 90.448(12)°; R₁ = 0.0529. The compound forms a Rb₆N₆ skeleton of a double cube with a common face of two rubidium and two nitrogen atoms, the latter being fivefold coordinated by four rubidium atoms and the phosphorus atom. [CsNPPh₃]₄ · 2 toluene · 3³/₄ hexane ( 2 a ): space group Fd3, Z = 8, lattice dimensions at 123 K: a = b = c = 2679.7(1) pm; R₁ = 0.0405. [CsNPPh₃]₄ · 2 toluene ( 2 b ): space group P2₁/n, Z = 4, lattice dimensions at 193 K: a = 1418.9(1); b = 2258.9(1); c = 2497.6(1) pm; β = 91.055(6)°; R₁ = 0.0278. Both cesium compounds form Cs₄N₄ heterocubane structures which are different by means of the packing and by different bond angles at the cesium and nitrogen atoms.     

Pyrazolate thiocarbonylrhodium complexes. X-ray structure of [Rh(μ-3,5-Me2Pz)(CS)(PPh3)]2

The preparation and properties of complexes of general formulae [Rh(CS)-(HL)(PR₃)₂]ClO₄ (HL = pyrazole (HPz), 3-methylpyrazole (H3-MePz), 3,5-dimethylpyrazole (H3,5-Me₂Pz), PR₃ = triphenylphosphine, tricyclohexylphosphine) and [(PR₃)₂(CS)Rh(μ-Pz)AuPPh₃]ClO₄ are reported. Complexes of the first set react with potassium hydroxide to give [Rh(μ-L)(CS)(PPh₃)₂ or RhPz(CS)(PR₃)₂ complexes. The structure of the complex [Rh(3,5-Me₂Pz)(CS)(PPh₃)]₂ has been determined by X-ray diffraction methods. The crystals are monoclinic, space group P2₁/c, with Z = 4 in a unit cell of dimensions a = 12.700(11), b = 17.217(16), c = 23.041(18) Å, β = 116.55(8)°. The structure has been solved by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.059 for 1978 independent reflections. The structure consists of dimeric complexes, in which each rhodium atom is in a square-planar environment being bonded to a carbon atom of a thiocarbonyl ligand, a phosphorus atom of a triphenylphosphine molecule and to two nitrogen atoms of pyrazolate ligands bridging the metal atoms. The dihedral angle of 71.1° between such two square planes leads to a bent configuration with an intramolecular rhodium-rhodium distance of 3.220 Å. The thiocarbonyl and triphenylphosphine ligands are in a trans disposition.     

Compounds of molybdenum and tungsten with high specific surface area: II. Carbides

Temperature-programmed carburization of W₂N and Mo₂N powders in CH₄H₂ mixtures up to 1150 and 970 K, respectively, leads to metastable face-centered cubic carbide phases. The reaction is topotactic in the sense that the face-centered cubic structure of the metal atoms remains unaltered, while the nitrogen and carbon atoms exchange their interstitial positions. Thus, the product retains the structure, crystallite size, and high specific surface area of its nitride parent, namely, 55 and 185 m² g^?1 for β-WC_1?x and α-MoC_0.45, respectively.     

Structure of C, N-chelated nButyltin(IV) fluorides and their use as fluorinating agents of some chlorosilanes, chlorophosphine and metal halides

The tin atom in the solid-state structure of {2-[(CH₃)₂NCH₂]C₆H₄}nBu₂SnF is five coordinated with carbon atoms in equatorial and fluorine and nitrogen atoms in axial positions. The fluorination of {2-[(CH₃)₂NCH₂]C₆H₄}nBuSnCl₂ is described by NMR methods. The successful attempts to fluorinate various chlorosilanes, chlorophosphine and metal halides are also reported.