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.     

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.     

The chemistry and the sterechemistry of Poly(N-Alkyliminoalanes: XIII. The crystal and molecular structure of the hexamers (ClAlN-i-Pr)6 and (Me0.83H0.17AlN-i-Pr)6MeAlN-i-Pr)6

The crystall and molecular structures of (ClAlN-i-Pr)₆ (I), and of (Me_0.83H_0.17AlN-i-Pr)₆(MeAlN-i-Pr)₆ have been determined by single crystal three-dimensional X-ray analysis. Block-matrix least-squares refinements led to conventional R factor of 0.039 for I and 0.037 for II. The compounds are isostructural, as the cage molecules consist of a prismatic hexagonal framework, (AlN)₆, similar to that observed for the parent hydrogenated analogue (HAlN-i-Pr)₆.Some differences in bond distances and angles are discussed, in connection with the different Al-bonded substituents. Crystal data: I, trigonal space group R$\text{3}$; a = 17.083(2), c = 9.652(1); Z = 3; D_c 1.46 g cm^?3; II, trigonal space group R$\text{3}$, a = 17.378(3), c = 9.706(3) »; Z = 3; D_c 1.15 g cm^?3.     

The preparation and crystal structure of bis(bis(diphenyl-phosphino)ethane)carbonylformylosmium(II) hexafluoroantimonatedichloromethane (1/1)

Reaction of trans[Os(CO)₂(dppe)₂]²⁺ with [KHB(OPrⁱ)₃] gives the formyl complex trans[Os(CHO)(CO)(dppe)₂][SbF₆] which is thermally very stable; the crystal structure shows it to have trans stereochemistry and a long Os-C bond.     

The crystal structure of copper bromide telluride

The crystal structure of CuBrTe has been determined. The compound is tetragonal with unit cell dimensions a = 16.417Å, c = 4.711Å, Z = 16, and space group I4₁/amd. Three-dimensional counterdiffraction intensity data (MoKα) were refined with full-matrix least-squares to a conventional unweighted R of 0.066. The structure consists of infinite tellurium spirals with bromine tetrahedra interspersed. Two basic types of disordered copper atoms were found. One type is at the center of the bromine tetrahedra and has several possible locations for each atom. The other type of copper lies on two possible sites in a distorted tetrahedral environment with tellurium and two bromine atoms as nearest neighbors.     

The crystal and molecular structure of hexadecaphenyloctasiloxyspiro(9,9)titanate(IV)

The crystal and molecular structures of the title compound have been determined by single crystal X-ray diffraction methods. In the spiro molecule, the metal atom has a geometry very close to tetrahedral, with OTiO angles of 107.9–111.0(2)° and very short TiO bonds of length 1.777–1.791(5)Å. The two TiO₅Si₄ rings have different, ill-defined conformations; the SiO bond lengths and SiOSi angles are similar to those in (SiO)_n rings.     

Synthesis and molecular structure of hydrido(tetrahydroborato)(1,1,1-tris(diphenylphosphinomethyl)ethane)-iron(II)

Sodium tetrahydroborate reacts with iron(II) tetrafluoroborate and 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) to give the complex (triphos)-FeH(BH₄) whose molecular structure, determined from X-ray data consists of monomolecular units in which the iron atom is six-coordinated by the three phosphorus atoms of the ligand, two hydrogen atoms of the BH₄ group, and a hydridic hydrogen atom. Variable temperature ³¹P NMR spectra reveal stereochemical non-rigidity of the complex in solution.     

Reactions of some electrophilic olefins with (carbonato)bis(triphenylphosphine)- and (carbonato)bis(triphenylarsine)-platinum complexes

Carbonato complexes L₂PtCO₃ (L = PPh₃ or AsPh₃) react with certain electrophilic olegins, such as 1,1-dicyanoolefins, under mild conditions to liberate CO₂. The reaction of L₂PtCO₃ with tetracyanoethylene at room temperature is solvent dependent, and in alcoholic solvents, in contrast to an earlier report, the dicyano complexes, L₂Pt(CN)₂, and tricyanoethenolato complexes, L₂Pt(CN) [OC(CN)C(CN)₂] have been isolated and identified.     

The preparation and X-ray crystal and molecular structure of (α,1,2-η-6-methylbenzyl) bis(triphenylphosphine)rhodium(I)

Reaction of [RhCl(PPh₃)₃] with [o-MeC₆H₄CH₂MgBr] affords high yields of the non-fluxional complex, [Rh(CH₂C₆H₄Me)(PPh₃)₂] which has been shown crystallographically to contain a 1-3-η-benzyl group bound through the phenyl carbon atom that is not substituted with the methyl group. Crystals of this compound are triclinic, space group P$\text{1}$, with a = 10.561(6). b = 17.705(3), c = 10.934(4) Å, α = 80.69(3), β = 116.86(4), γ = 102.30(4)° and Z = 2. The structure was solved via the heavy-atom method and refined to R = 0.032 using 5379 diffractometer data with I > 1.56(I). Attempts to prepare π-bonded xylylene complexes from this compound by reaction with base have been unsuccessful, but protonation followed by recrystallisation from acetone gives [Rh{(CH₃)₂CO}₂(PPh₃)₂]BF₄.     

Preparation of niobium and tantalum organoimido complexes from reactions of the pentahalides with amines: The crystal and molecular structure of bis(t-butylamine)bis(t-butylimido)bis(μ-ethoxy)tetrachloroditantalum

MCl₅ (M = Nb, Ta) reacts with 2 equivalents of Me₃SiNHCMe₃ to give [M(NCMe₃)Cl₃(NH₂CMe₃)] from which [M(NCMe₃)Cl₃(PMe₃)₂] is obtained on addition of PMe₃. One equivalent of Me₃SiNHCMe₃ reacts with MCl₅ in the presence of 3 equivalents of PMe₃ to give [M(NCMe₃)Cl₃(PMe₃)₂] and PMe₃HCl. MCl₅ reacts with excess RNH₂ (R = CMe₃, CHMe₂, CH₂Me) to give [M(NR)(NHR)Cl₂(NH₂R)] and 3 equivalents of RNH₃Cl. One equivalent of alcohol replaces the amido ligand in [M(NCMe₃)(NHCMe₃)Cl₂(NH₂CMe₃)] to give [M(NCMe₃)(OR)Cl₂(NH₂CMe₃)]₂ (M = Nb, R = OCMe₃; M = Ta, R = OEt). The structure of [Ta(NCMe₃)(μ-OEt)Cl₂(NH₂CMe₃)]₂ was determined by single-crystal X-ray diffraction methods. Crystals are triclinic, space group P$\text{1}$ with a = 9.900(5), b = 10. 161(17), c = 9.017(6) Å and α = 103.91(8), β = 97.77(4), γ = 64.40(7)°. The structure was solved by Patterson and Fourier methods and refined to an R value of 0.062 for 1319 observed data. The TaN_imido and TaN_amino bond lengths are 1.70(2) Å and 2.28(2) Å, respectively; the bridging TaO bond lengths are 2.01(2) Å and 2.32(2) Å, the longer one lying trans to the imido function.     

The molecular structure of p-bis(trimethylsilyl)-benzene from gas phase electron diffraction

Nearly regular tetrahedral silicon bond configuration and a considerably distorted ring characterize the p-bis(trimethylsilyl)benzene molecular geometry according to an electron diffraction study. The SiC_methyl bond is longer than the SiC_phenyl bond, in agreement with expectation but contrary to an X-ray diffraction determination. The extent of ring deformation is consistent with the electropositive character of the trimethylsilyl substituent and with the structural variations in other para-disubstituted benzene derivatives. The electron diffraction data are consistent with either free rotation around the SiC_phenyl bonds or with a rotamer deviating by about 15° from the eclipsed form. The following bond lengths (r_g, pm) and bond angles (°) have been determined with parenthesized estimated total errors: (CC)_mean 140.8(3), (C_ipso)(C_orthoC_meta) 1.6(7), (SiC)_mean 188.0(4), (SiC_methyl)(SiC_phenyl) 3.3(7), (CH)_methyl 111.3(3), CC_ipsoC 115.7(6), and C_phenylSiC_methyl 109.2(4).     

Crystal and molecular structure at −35°C of (π-cyclobutadiene)dicobalt hexacarbonyl

The structure of cyclobutadienedicobalt hexacarbonyl, (C₄H₄)Co₂(CO)₆, has been determined by single crystal X-ray diffraction techniques with data gathered at ?35°C by counter methods. Crystals form as red prisms in orthorhombic space group Pnma, with lattice parameters (at ?35°C) a = 12.916(3), b = 10.353(2) and c = 9.118(3) Å for a unit cell with four molecules of (C₄H₄)Co₂(CO)₆. The molecules have rigorous C_s symmetry, with a π-cyclobutadiene ring bound to the Co atom of a Co(CO)₂ moiety which, in turn, is linked to a Co(CO)₄ fragment through the metal atoms. Apparently to decrease repulsion between the cyclobutadiene ring and the bulky Co(CO)₄ group, the four-membered ring is tilted, and as a consequence the CoC₄H₄ interaction is unsymmetrical (CoC(ring) = 1.980(3) to 2.048(4) Å). Full-matrix least-squares refinement of the structure has converged with a R index (on |F|) of 0.027 for 1539 symmetry-independent reflections with I_o > 2.0σ(I_o) within the Mo-K_α shell defined by 4° < 2θ < 60°.     

The reaction of allene with β-diketonatoiridium(I) complexes: formation and crystal structure of a new bis-β-allylic derivative of iridium(III)

The reaction of allene with (Hfacac)Ir(η-C₈H₁₄)₂ to give a new bis-η-allylic complex of iridium(III) containing an allene tetramer is described; the X-ray structure of this compound is reported.     

Cationic hydrido-olefin complexes of ruthenium (II). The crystal structure of hydrido(1,3-butadiene)tris-(dimethylphenylphosphine)ruthenium(II) hexafluoro-phosphate

A route to the stable hydrido-diene salts [(diene)RuHL₃] PF₆, (diene = cycloocta-l,5-diene, hexa-l,3-diene and buta-1,3-diene, L = PMe₂ Ph; diene = cycloocta-l,5-diene, L = P(OMe)₃, P(OCH₂)₃ CMe P(OMe)Ph₂ and PMePh₂) has been found and the structure of [RuH(C₄H₆)(PMe₂Ph)₃] PF₆ has been determined by X-ray diffraction.     

The structure and magnetic properties of chromium(III) molybdate

Magnetic susceptibility measurements have shown that Cr₂(MoO₄)₃ orders magnetically at 42 K. Powder neutron diffraction experiments at 295 and 5 K indicate that Cr₂(MoO₄)₃ is chemically and magnetically isostructural with the L-type ferrimagnet Fe₂(MoO₄)₃, and has a magnetic moment of 2.5 ± 0.2 μ_B per cation at 5 K. The limitations imposed on powder neutron diffraction methods by particle-size effects are discussed.     

The preparation and structure of (divinylcyclohexene)nickel—phosphine complexes

Butadiene reacts with (hexatriene)nickel—phosphine complexes to give (divinylcyclohexene)nickel derivatives; the structure of the product from the reaction involving octatriene has been determined crystallographically.     

Polysilane derivatives of the transition metals II. The crystal and molecular structure of [tris(trimethylsilyl)silyl]pentacarbonylmanganese, (Me3Si)3SiMn(CO)5

The crystal and molecular structures of [tris(trimethylsilyl)silyl]pentacarbonylmanganese, (Me₃Si)₃SiMn(CO)₅, have been determined from three-dimensional X-ray data obtained by counter methods. The compound crystallizes in space group P$\text{1}$ of the triclinic system, with two molecules in a unit cell of dimensions: a = 9.002(2), b = 9.655(2), c = 15.639(3) Å, α = 83.66(1), β = 105.65(1), γ = 114.61(1)°.The observed and calculated densities are 1.20 (±0.03) and 1.23 g-cm^?3 respectively. Full-matrix least-squares refinement of the structure has led to a final value of the conventional R factor of 0.059 for the 818 independent reflections having F² > 3σ(F²).The coordination geometry about the manganese atom is approximately octahedral and, about the silicon atom bonded to the manganese atom, tetrahedral.The relative orientations of carbonyl and trimethylsilyl groups, when viewed down the MnSi bond, appear consistent with minimization of energy due to nonbonded interactions.Two of the equatorial carbonyl groups are displaced out of the equatorial plane towards the silicon ligand by 6°. The SiMn bond is 2.564(6) Å long and has no multiple character.     

The crystal structure of Cu4(PO4)2O

Cu₄(PO₄)₂O crystallizes in the space group $\text{P}\text{1}$ with a = 7.5393(8) Å, b = 8.1021(9) Å, c = 6.2764(8) Å, α = 113.65(1)°, β = 98.42(1)° and γ = 74.19(1)°. The structure was refined by full-matrix least-squares techniques using automatic diffractometer data to R = 0.046 (R_w = 0.056). Four unique copper atoms are in six, five-, and four-coordinated polyhedra which are linked together to form a three-dimensional network. The structure is best described in terms of a cubic close-packed array of oxygen atoms with one-tenth of the possible anion sites vacant.     

Oxidative addition reactions of dicyclopentadienyltin(II) and of tin(II) bis(acetylacetonate) with organic halides. The preparation of compounds of the type RSn(acac)2X

Oxidative addition reactions of tin(II) bis(acetylacetonate) with organic halides provide a route to new monoorganotin(IV) bis(acetylacetonate) halides. Dicyclopentadienyltin(II) undergoes oxidative addition with methyl iodide, diiodomethane and ethyl bromoacetate, but with allyl bromide, benzyl bromide and triphenylmethyl bromide carbon—carbon coupling reactions and the formation of the corresponding cyclopentadienyltin(II) halide take place. Some of the reactions are accelerated by light. NMR spectroscopic data show that the RSn(acac)₂X compounds have a cis-configuration. The compounds YCH₂Sn(acac)₂X (e.g. Y = I, CHCH₂, COOEt) provide the first examples of diastereo-topic non-equivalence of methylene protons in organotin compounds containing a hexacoordinate chiral tin centre.