Studies on organometallic compounds with hetero multiple bridges : V. Crystal and molecular structure of the parent rhenium complex Re2Br2(CO)6(THF)2 and substituted products of tricarbonylrhenium(I) derived from it

Reactions of the tetrahydrofuran adduct Re₂Br₂(CO)₆(THF)₂ with some phosphorous- and nitrogen-containing donors under mild conditions are reported, which led to the formation of substituted products of tricarbonylrhenium(I). Bromide abstraction from the THF adduct by secondary amines and CS₂ produced the dithiocarbamato derivatives Re(S₂CNR₂)(CO)₃(HNR₂) whose behaviour in solution with CO was also investigated. Mass spectral data for some of the substituted products have been measured. The title compound crystallizes in the space group P2₁/n with cell constants a = 8.661(2), b = 11.251(3), c = 11.424(3) Å and β = 110.36(2)°, U = 1043.67 ų and D_calc = 2.686 g cm^?3, Z = 2. The molecule consists of a planar Re₂Br₂ moiety, as demanded by symmetry. The two THF groups are on opposite sides of this plane and the three CO groups around each rhenium atom are arranged in a fac arrangement. The unique ReBr distances are 2.642(5) and 2.644(4)Å, while the ReO distance is 2.129(31) Å. The ReBrRe and BrReBr angles are 97.3(2) and 82.7(1)°, respectively. The Re?Re nonbonding distance is 3.967(3) Å. The THF ligands consist of a nearly planar C₄ fragment (maximum deviation from planarity 0.06 Å), while the oxygen is 0.348 Å out of that plane, the angle defined by the C₄ plane and the COC fragment of the THF ligand being 24.99°. Final values of the discrepancy indices are R(F) = 0.074 and R_w(F) = 0.095.     

The preparation and structures of Ph3AsGaI3 and [Ph3AsI][GaI4]

Colourless crystals of Ph₃AsGaI₃ (1) have been prepared by reaction of triphenylarsine with GaI₃·OEt₂ in diethyl ether. The structure of 1, in which the length of the AsGa donor-acceptor bond is 2.490(2) Å, has been determined by an X-ray diffraction study. In contact with the solvent phase, 1 is transformed into yellow crystals of [Ph₃AsI][GaI₄], 2 which has been structurally characterised by Raman spectroscopy (AsI stretching at 196 cm⁻¹) and by X-ray diffraction. The salt 2 is the first arsenic(V) iodo complex to have been examined crystallographically; the AsI bond distance is 2.485(1) Å.     

Synthesis and structure of tetrakis(phenylenethiourea)tellurium(II) chloride dihydrochloride,C28H26N8S4Cl4Te

Reaction of tellurium(IV) with excess phenylenethiourea(2-mercaptobenzimidazole) in aqueous methanolic hydrochloric acid leads to the formation of Te(II) complex, tetrakis(phenylenethiourea)tellurium(II) chloride dihydrochloride. The characterisation and crystal structure of the complex are reported. The crystals are monoclinic, space group P2₁/c, a = 13.939(5), b = 26.523(9), c = 4.873(2) Å, β = 100.29(4)°, V = 1772.6 ų, M = 872.4, D_c = 1.651 g cm^?3, Z = 2, F(000) = 868, μ(MoK_α) = 1.298 mm^?1. Final R = 0.055 and R_W = 0.056 for 918 independent reflections. The tellurium atom in the molecule lies at the crystallographic centre of symmetry and is bonded to four phenylenethiourea sulphur atoms in a square planar arrangement with TeS(1) = 2.678(6), TeS(2) = 2.674(5) Å and S(1)TeS(2) is 90.5(3)°. The ligand behaves as a thione. Chlorine atoms remain outside the coordination sphere of the Te and stabilise the packing arrangement in the unit cell through hydrogen bondings to nitrogen atoms.     

X-ray crystal structure of tribenzylaluminum · diethyl etherate

The crystal structure of tribenzylaluminum · diethyl etherate has been determined by single crystal X-ray diffraction techniques. It crystallizes in the monoclinic system, space group P2₁, with unit cell dimensions of a 8.106(1), b 15.098(2), c 10.037(1) Å, β 111.02(1)°, V 1146.6(3) ų, and Z = 2. The final full matrix least-squares refinement on 1139 data gave R_F 3.8 and R _wF 5.2%. The compound is similar to other organoaluminum adducts yielding a four coordinate aluminum atom with average AlC distances of 1.986 and an AlO distance of 1.901(4) Å which is significantly shorter than the AlO distance observed in other ether adducts. The average CAlC and CAlO angles are 113 and 106°, respectively.     

Synthesis and structural characterization of a polar Os(II,III) complex,Os2(fhp)4Cl

The title compound was prepared by prolonged reaction of Os₂(CH₃COO)₄Cl₂ with Hfhp (Hfhp = 6-fluoro-2-hydroxypyridine) in refluxing toluene in the presence of LiCl. The product, Os₂(fhp)₄Cl (1), is a result of ligand displacement with a concomitant core reduction of Os₂⁶⁺ to Os₂⁵⁺. Crystals were grown by slow diffusion of hexane into a dichloromethane solution of 1. Crystallographic data are as follows: tetragonal crystal system, space group I4mm (No. 107), a = b = 11.000(3) Å, c = 13.142(2) Å, V= 1590(1) ų, Z = 2. The molecule possesses crystallographic 4mm symmetry, with the OsOs bonds lying along the four-fold axes. The four fhp ligands are arranged in a polar fashion around the diosmium core, blocking one axial site. The second axial position is occupied by a chloride ion. The principal distances in 1 are: Os(1)Os(2) = 2.341(1) Å, Os(1)N = 2.027(12) Å, Os(2)O = 2.014(5) Å, Os(2)Cl = 2.487(7) Å. The title compound was also investigated by several physical methods. The electrochemistry as determined by cyclic voltammetry revealed two processes: a reversible, one-electron reduction at E_ox = −0.63 V in dichloromethane and an irreversible oxidation at E_ox = +0.95 V in dichloromethane vs Ag-AgCl at room temperature. The electronic spectrum shows strong bands at 413 nm (ε = 4290 M⁻¹ cm⁻¹), 309 nm (ε = 23,560 M⁻¹ cm⁻¹) and at 294 nm (ε = 26,500 M⁻¹ cm⁻¹) as well as shoulders at 334 and 261 nm.     

Antiferromagnetic complexes involving metalmetal bonds : I. Synthesis and molecular structure of an antiferromagnetic dimer with a CrCr bond

The binuclear complex (C₅H₅)₂Cr₂(S)(SCMe₃)₂ was prepared by refluxing a solution of chromocene and t-butylmercaptane in heptane. The structure of the product was determined by single crystal X-ray diffraction. The chronium atoms are linked by a sulphide bridge (SCr 2.24 Å;, <CrSCr 74.1° and two SCMe₃ bridges (CrS 2.38 Å;, <CrSCr 68.3–69.3°). The two cyclopentadienyl ligands (CC 1.41 Å;, CrC 2.23 Å;) are in apical positions, their ring planes being parallel to each other. The complex is an antiferromagnet (?2J cm^?1) despite the small CrSCr angles and short chromiumchromium distance (2.689 Å;) indicative of strong CrCr bonding.     

The chemistry and the stereochemistry of poly(N-alkyliminoalanes) : IV. The preparation and crystal structure of [H(HAlN-i-Pr)5AlH2]·LiH/Et2O

The compound [H(HAlN-i-Pr)₅AlH₂]·LiH/Et₂O has been prepared, and its crystal and molecular structure has been determined from single-crystal, three-dimensional X-ray diffractometer data. The molecular structure is a pseudohexameric cage, consisting of a five-membered fragment, AlNAlNAl, crosslinked to a six-membered cyclohexane type ring, (AlN)₃. The hydrogen atom of LiH is indistinguishable from the other hydridic hydrogens, so that the N-isopropyliminoalane part of the molecule may be considered as an anion with a formal charge of ?1. The lithium cation is linked to two adjacent molecules through three LiHAl bridges, the fourth position of its tetrahedral coordination being occupied by the oxygen of diethyl ether. Large distortions of the tetrahedral valence angles occur, both on the aluminum atoms and on the nitrogen atoms, together with a noticeable spread of the AlN bond lengths, averaging 1.919(4) Å. Colourless crystals of the compound have the following crystal data: orthorhombic space group Pna2₁; a = 19.76(2), b = 10.38(1), c = 16.60(2) Å; Z = 4; calculated density 1.048 g/cm³. The structure has been refined by block-matrix least-squares methods, using 2487 independent reflections, to an usual R factor of 5.9%.     

Crystal and molecular structure of tricyclopentadienyltetrahydrofuranuranium(III), (η5-C5H5)3U·OC4H8

Tricyclopentadienyltetrahydrofuranuranium(III), (η⁵-C₅H₅)₃U·OC₄H₈, crystallizes in the centrosymmetric monoclinic space group P2₁/n with a 8.248(3), b 24.322(17), c 8.357(4) Å, β 101.29(5)°, V 1644.0 ų and ρ(calc) 2.04 g cm^?1 for Z = 4 and mol.wt. 595.0. Diffraction data (Mo-K_α, 2θ(max) 45°) were collected on an Enraf-Nonius CAD4 diffractometer and the structure was refined to R_w(F) 4.7% for those 1530 reflections having I > 2σ(I). The molecule consists of a distorted tetrahedral arrangement of THF and (η⁵-C₅H₅) ligands with CpUCp angles in the range 110.4–122.4° and CpUO angles between 90.2 and 106.0°. Individual uranium-carbon distances range from 2.76(2) to 2.82(2) Å and average 2.79[1] Å. The uranium-oxygen distance of 2.551(10) Å suggests a 10-coordinate U³⁺ radius of 1.20 Å in this class of compounds.     

Synthesis and structure of hexabenzyl-dimolybdenum (MoMo)

The homoleptic benzyl Mo₂(CH₂Ph)₆ has been obtained by reaction of either MoCl₄(thf)₂ or Mo₂(OPrⁱ)₆ with Mg(CH₂Ph)₂. The dark-red, sparingly soluble complex has been characterized by ¹H and ¹³C NMR as well as by a solid-state structure analysis. Pertinent bond distances (Å) and angles (°) for the unbridged, ethane-like molecule which contains crystallographic S₆-symmetry are: MoMo = 2.175(1), MoC = 2.162(2), MoMoC = 97.61(6), and MoCC(Ph) = 98.9(1).     

Antiferromagnetic complexes with a metal—metal bond: VIII. Synthesis and structure of the antiferromagnetic heteronuclear cluster, “butterfly” (or “metal-chain”), (Cp4Cr2Ni2)(μ3-S)2(μ4-S)

By heating the mixture of solutions of (CpCrSCMe₃)₂S (I) in benzene and [CpNi(CO)]₂ in pentane followed by chromatography on alumina, dark cherry-red needles of the heteronuclear cluster (Cp₄Cr₂Ni₂)(μ³-S)₂(μ⁴-S) (II) were obtained, whose structure was established on the basis of a complete X-ray analysis. The crystals are rhombic, spatial group Pbca; a = 12.07(1), b = 18.50(2), c = 17.36(1) Å, Z = 8. The metallic skeleton of II has the “butterfly” or “metal-chain” structure with a direct CrCr bond (2.62(1) Å) and inequivalent CrNi bonds, 2.86(1) and 2.64(1) Å, while the Ni·Ni distance is nonbonding (4.34(1) Å). The NiCr₂ triangle planes produce a dihedral angle of 127°. The two μ³-bridged sulfur atoms locate under these triangles whereas the third sulfur atom is μ⁴-bridging coordinating all four metal atoms in the cluster with mean NiS and CrS distances of 2.29(1) and 2.25(1) Å, respectively. The Ni₂S₃ group is planar and almost perpendicular to the CrCr axis. Complex II is anti-ferromagnetic and its exchange parameter — 2J (418 cm^-1) is close to that found for the initial binuclear complex I (— 2J = 430 cm^-1 with a CrCr bond length of 2.689(8) Å). The role of the Ni coordination number in the generation of II is discussed.     

Titan-stickstoff-verbindungen: XIX. Darstellung Und Struktur Des Spirocyclischen Titan-Silylamids Ti(NMeSiMe2MeN)2

deTi(NMeSiMe₂SiMe₂MeN)₂ (I) has been obtained from the reaction of LiNMeSiMe₂SiMe₂NMeLi with TiBr₄. It forms yellow crystals ofconsiderable stability which can be sublimed without decomposition. Its ¹H NMR, IR and Raman spectra are reported. The crystal structure of I was determined by X-ray diffraction and was refined to R = 0.059. The titanium atom in the spiro type molecule is tetrahedrally coordinated by nitrogen atoms with TIN distances of 1.905 Å SiN and SiSi distances in the slightly puckered five-membered rings are 1.733 and 2.355 Å, respectively.     

Die kristall- und molekúlstruktur der dimeren dimethylaluminium- und dimethylgallium-N,N′-dimethylacetamidine [(CH3)2M(NCH3)2CCH3]2 (M = Al,Ga)

Dimethylaluminium- and dimethylgallium-N,N′-dimethylacetamidine (I and II) are doubly associated forming a puckered eight-membered ring. They crystallize isostructurally in the monoclinic space group P2₁/c with two dimers per unit cell. The lattice constants of I are a 8.187, b 7.266, c 14.778 Å, β 103.58° and those of II a 8.163, b 7.277, c 14.835 Å, β 103.46°. The MN and the NC bond lengths within the rings are nearly equal, their mean values are for I: AlN 1.925 Å, CN 1.330 Å and for II: GaN 1.979 Å, CN 1.335 Å. This is also true for the exocyclic bond lengths with average values AlC 1.975 Å, NC 1.474 Å, CC 1.509 Å (for I) and GaC 1.998 Å, NC 1.484 Å and CC 1.507 Å (for II). The metal atoms are tetrahedrally coordinated, and the distortion is only slight. The final R-values are 0.034 and 0.056, respectively.     

The crystal structure of Mg51Zn20

The crystal structure of Mg₅₁Zn₂₀, a phase designated conventionally as “Mg₇Zn₃,” has been determined by the single-crystal X-ray diffraction method. It was solved by the examination of a Patterson synthesis, and refined by the ordinary Fourier and least-squares method; the R value obtained was 4.8% for 1167 observed reflections. The crystal is orthorhombic, space group Immm, with a = 14.083(3), b = 14.486(3), c = 14.025(3) Å, and Z = 2. There are 18 independent atomic sites, Zn1Zn6, Mg1Mg10, A, and B, and the last two sites are statistically occupied by Zn and Mg atoms with the occupancies; 0.46(2)Zn7 + 0.52(2)Mg11 and 0.24(2)Zn8 + 0.74(2)Mg12, for A and B, respectively. The structure of the crystal is described as an arrangement of icosahedral coordination polyhedra, to which all the atomic sites but Zn3 site belong. In this arrangement the Zn atoms other than the Zn3 and Zn8(B) center the icosahedral coordination polyhedra with coordination number 12. The Zn3, Zn8 atoms, and all the Mg atoms except Mg11(A) are located at the centers of various coordination polyhedra with the coordination numbers from 11 to 15. The distances between neighboring atoms are 2.71–3.07, 2.82–3.65, and 2.60–3.20 Å for ZnZn, MgMg, and ZnMg, respectively.     

Author index for volume 31

The solid state reactions of MMoO₄ (M = Mg²⁺, Fe²⁺, and Ni²⁺) and orthorhombic TeO₂ were investigated. A new metal telluromolybdate MgTeMoO₆ was obtained in the case of Mg; its structure belongs to the orthorhombic system with unit-cell dimensions a = 5.262Å, b = 5.028 Å, c = 8.880 Å. Fe₂(MoO₄)₃ and a new compound were formed in the case of Fe. The new compound is made up with Fe³⁺ ions and its chemical formula cannot be recognized as FeTeMoO₆. In the case of Ni a complex reaction mixture is obtained. An explanation is given of the ability of M²⁺ ions to form the metal telluromolybdates. The catalytic properties of MgTeMoO₆ are discussed and compared to those of the other metal telluromolybdates.     

Etude EXAFS de la structure pyrochlore type RbNiCrF6

EXAFS studies of modified pyrochlore RbNiCrF₆-like structure have been performed to obtain independent informations about the local environment of M^II and M^III ions. MF distances (for example, ZnF = 2.01 Å and GaF = 1.89 Å in CsZnGaF₆) were found to be consistent with mean distances observed in well-known fluoride compounds and their significant difference establishes that the Fd3m space group does not apply at the local scale. With a near-constant MM distance, locally different MF distances lead to variable MFM angles and can explain the large thermal parameter values found in X-ray determinations.     

The crystal structures of 1-allyl-1-bromo-3,4-benzo-1-telluracyclopentane [C8H8Te(C3H5)Br], 1-phenacyl-1-bromo-3,4-benzo-1-telluracyclopentane [C8H8Te(C8H7O)Br] and 1-deuteromethyl-1-iodo-3,4-benzo-1-telluracyclopentane [C8H8Te(CD3)I]; the trans effect in organotellurium bromides and iodides

The crystal structures of the title compounds have been determined from three-dimensional X-ray counter data.C₈H₈Te(CH₂CHCH₂)Br (I) is orthorhombic, space group Pbca with a 9.642(1), b 25.586(7), c 9.680(3) Å, Z = 8. The structure has been refined to R 5.2% for 1262 observed reflections.C₈H₈Te(CH₂COPh)Br (II) is orthorhombic, space group Pccn with a 23.593(6), b 14.337(3), c 9.180(2) Å, Z = 8. R = 5.5% for 1374 reflections.C₈H₈Te(CD₃)I (III) is orthorhombic, space group Pbca with a 11.200(3), b 15.976(2), c 23.328(3) Å, Z = 16. R = 5.6% for 2142 reflections.In I and II, tellurium is coordinated in an approximately octahedral geometry by the organic residues and three halogen contacts, with TeC and TeBr distances in the ranges 2.14(1)–2.19(1) Å and 3.328(2)–3.368(2) Å in (I) and 2.12(1)–2.18(1) Å and 3.292(2)–3.391(2) Å in II.In III, each of the two crystallographically independent complexes has tellurium coordinated in a distorted octahedral geometry. The TeC bond lengths are 2.10(2)–2.16(2) Å. In each case two TeI distances are in the range 3.596(2)–3.688(2) Å and a third, longer interaction (3.870(2) and 4.112(2) Å) completes the coordination.In each of the structures I–III the three covalent TeC bonds are oriented cis within the octahedra and exert a trans bond-lengthening effect on the Tehalogen interactions, precluding covalent-type bonding; the structures are essentially ionic, (C₈H₈TeR)⁺ cations and halide anions forming extended arrays.     

Direct synthesis from MoCl3(THF)3 of a complex containing the [Mo3S4]4+ core

By reaction of MoCl₃(THF)₃ with NaSH in tetrahydrofuran, followed by addition of Me₂PCH₂CH₂PMe₂(dmpe), then chromatography on silica-gel, and finally addition of NH₄PF₆, the compound [Mo₃S₄Cl₃(dmpe)₃]PF₆·CH₃OH was prepared in moderate yield. X-ray crystallography showed the presence of a chiral cation based on a Mo₃S₄ core with chelating dmpe units arranged like the blades of a ship's screw. The three Cl atoms fill the remaining octahedral sites on each metal atom. The compound crystallizes in space group R3c with (hexagonal) cell dimensions of a = 15.310(7) Å, c = 30.640(3) Å and Z = 6. The [Mo₃S₄Cl₃(dmpe)₃]⁺ ion and the PF₆⁻ ion each have crystallographic C₃ symmetry. The principal distances and theirs esds are: MoMo, 2.766(4) Å; Mo(μ₃-S), 2.360(9) Å; Mo(μ₂-S), 2.290(7) Å, 2.336(7) Å; MoP, 2.534(8) Å, 2.605(8) Å; MoCl, 2.473(7) Å; PF, 1.56(2) Å, 1.64(3) Å. The correct enantiomer was obtained by refining both to convergence, which give R = 0.059 and R = 0.064.     

Isodimorphism of the salts 2RbCl · MIICl2 · 2H2O (MII = Mn,Fe, Co,Cu)

The three-component systems RbClMnCl₂H₂O, 2RbCl · CoCl₂ · 2H₂O2RbCl · CuCl₂ · 2H₂OH₂O, 2RbCl · CoCl₂ · 2H₂O2RbCl · MnCl₂ · 2H₂OH₂O have been studied at 25°C. In the 2RbCl · CoCl₂ · 2H₂O2RbCl · CuCl₂ · 2H₂OH₂O system, a discontinuous series of mixed crystals is formed and in the 2RbCl · CoCl₂ · 2H₂O2RbCl · MnCl₂ · 2H₂OH₂O system, a continuous series is present.The unit cell parameters of the 2RbCl · CoCl₂ · 2H₂O double salt were determined: a = 5.586(2) Å, b = 6.469(3) Å, c = 6.988(2) Å, α = 65.31(3)°, β = 87.69(3)°, γ = 84.65(4)°, volume 228.4 ų, Z = 1.The results obtained and discussed in conjunction with the crystal structure data suggest that for 2M^ICl · M^IICl₂ · 2H₂O type salts the triclinic structure is stable only when the large rubidium and cesium ions participate in combinations with non-Jahn-Teller metal(II) ions. In the cases of Jahn-Teller metal(II) ions or with potassium or ammonium ions a tetragonal structure is always stable.     

Barreleneiridium(I) complexes. Crystal structures of [Ir(Me3TFB)(η6-C6H4Me2)]ClO4 and [Ir(TFB)(η5-PhNPh2)]BF4·CH2Cl2 (TFB = tetrafluorobenzobarrelene)

A new series of cationic areneiridium(I) complexes of formula [Ir(barrelene)(arene)]⁺ or [Ir(barrelene)(PhNRPh)]⁺ (R= Ph or H) have been synthesized from neutral iridium complexes of the type [IrY(barrelene)]_x (barrelene = Me₃TFB, Y = Cl or OMe (x = 2), Y = acac (x = 1); barrelene = TFB, Y = OMe (x = 2), Y = acac (x = 1)). The crystal structures of [Ir(Me₃TFB)(1,4-C₆H₄Me₂)]ClO₄ and [Ir(TFB)(PhNPh₂)]BF₄·CH₂Cl₂ have been determined by X-ray diffraction. They crystallize in the space groups Pbca and Pna2₁ respectively with lattice constants of 17.6947(11), 15.8072(10), 16.0019(11) Å and 9.8059(2), 20.8097(9), 14.3367(4) Å. Final R factors were 0.063 and 0.042 for the observed data. Both complexes show a staggered arrangement between the arene and the TFB moieties and deviation from planarity of the coordinated arene ligands. In the second complex the IrC and NC distances, the CNC angle, the type of arene puckering, and the spectroscopic data indicate a distortion of the coordinated arene towards a η⁵-coordinated iminocyclohexadienyl form.     

Reduction of copper (II) chloride by molybdenum and rhenium biscyclopentadienyl hydrides. Investigation of the crystal and molecular structure of [(η5-C5H5)2Re]+[CuCl2]−

The reduction of copper (II) chloride by molybdenum and rhenium biscyclopentadienyl hydrides upon their interaction in donor-type solvents has been studied by NMR, X-ray diffraction, and magnetic methods. It is established that the ionic complex [(η⁵-C₅H₅)₂Re]⁺[CuCl₂]^? forms ortho rhombic crystals with a - 13.696(2) Å, b = 7.317(1) Å, c = 5.969(1) Å, space group Pm2₁n, Z = 2. The cyclopentadienyl rings make a bent-sandwich with an angle between the ring centres and Re atom of 150.1°; the ClCuCl angle being 174.8° and the ReCu minimum distance 4.346(29) Å. The solution of [(η⁵-C⁵H₅)²Re]⁺ [CuCl₂]^? seems to activate the CH bond of the C₅H₅ rings, which results in the addition of the [(C₅H₅)(C₅H₄)ReH]⁺ hydride ion.