Al Spek

The crystal and molecular structure of cyclopentadienyltin(II) chloride. The bonding of the cyclopentadienyl group in tin(II) compounds

Abstract The crystal and molecular structure of cyclopentadienyltin(II) chloride has been determined from three-dimensional X-ray data. The crystals are orthorhombic, space group Pc21n. The unit cell, of dimensions a = 5.711(5), b = 6.225(5), c = 17.24(2) A, contains four molecules. The structure has been refined by full matrix least squares techniques to a final R value of 0.083 for 717 independent reflections. In the crystal unsymmetrical tin-chlorine bridges are present between the units of C5H5SnCl. It is suggested that in cyclopentadienyltin(II) compounds the cyclopentadienyl group occupies more than one coordination site as a result of the donation of π electron density from the cyclopentadienyl ring into an empty acceptor orbital of the tin atom having π symmetry.

MONOMERIC ARYLCHROMIUM(II) COMPLEXES - THE CRYSTAL-STRUCTURES OF [CIS-MES2CR(THF)2](THF), [CIS-MES2CR(BIPY)](THF), [MES4CRLI2(THF)2](THF) AND PH4CRLI2(THF)4 (MES = 2,4,6-MESITYL, BIPY = 2,2'-BIPYRIDINE)

Abstract The square-planar geometry of the monomeric [Mes 2 Cr(THF) 2 ](THF) ( 1 ) and [Mes 2 Cr(bipy)](THF) ( 2 ) (Mes = 2,4,6-mesityl; bipy = 2,2′-bipyridine) was determined by X-ray diffraction analysis. Crystal data are as follows. 1 : orthorhombic, Pccn with a 12.447(3), b 14.500(2), c 16.593(2) A), V 2994.7(9) A 3 , Z = 4, R = 0.121, R w = 0.121. 2 : Monoclinic, P 2 1 / c with a 14.316(2), b 11.071(2), c 17.645(3) A, β 91.24(1)°, V 2795.9(3) A 3 , Z = 4, R = 0.060, R w = 0.068. Further reaction of 1 with an excess of MesLi or reaction of CrCl 2 (THF) 2 with 4 equiv. of PhLi, allows the isolation of the monomeric chromates [Mes 4 CrLi 2 (THF) 2 ](THF) ( 3 ) and Ph 4 CrLi 2 (THF) 4 ( 4 ) in crystalline form. Crystal data for 3 and 4 are as follows. 3 : orthorhombic, I 222 with a 8.703(1), b 14.129(1), c 17.993(1) A, V 2212.6(3) A 3 , Z = 2, R = 0.052, R w = 0.054. 4 : Triclinic, P 1 with a 9.187(1), b 10.263(1), c 10.851(1) A, α 110.77(1), β 92.16(1), γ 97.48(1)°, V 944.7(2) A 3 , Z = 1, R = 0.059, R w = 0.057.

EFFECT OF CONFORMATION OF CYCLIC SULFIDE LIGANDS ON THE MODE OF COMPLEXATION TO SILVER SALTS

The cyclic trisulfide 1,3,5-trithiane has a flattened chair conformation. It forms with AgSO3CF3 a dimeric complex wherein each silver is tetracoordinated bearing three sulfides and one triflate ion as ligands. On the other hand 1,4-dithiane, which also has a chair conformation, forms an infinite polymer with AgO2CCF3 wherein each silver is coordinated to two different dithianes and two different CF3CO2 ligands.

Internally coordinated organozinc-transition metal compounds. Crystal structure of (CH3)2N(CH2)3ZnW(ν-C5H5)(CO)3

Abstract The stabilities of simple and internally coordinated organozinc-transition metal compounds towards disproportionation have been investigated by the microwave titration technique. Simple alkyl- and aryl-derivatives disproportionate to such an extent as to preclude isolation. Internal coordination was found to stabilize the asymmetric compounds, and several derivatives containing the dimethylaminopropyl group were isolated. The crystal structure of one of them, Me 2 N(CH 2 ) 3 -ZnW(Cp)(CO) 3 , was determined by a single-crystal X-ray study. The crystals are orthorhombic, space group P 2 1 2 1 2 1 , with four molecular units in a cell with parameters a 8.406(1), b 12.179(2) and c 16.642(2) A. The structure was solved by standard Patterson and Fourier techniques. The refinement, with anisotropic temperature factors for the two heavy atoms, converged at R F = 0.092 ( R wF = 0.089) for 1536 observed reflections with I >2.5σ( I ). The molecule consists of a central tungsten atom, surrounded in a tetragonal pyramidal fashion by a cyclopentadienyl group in the apical position and three carbon monoxyde molecules and a zinc atom occupying the basal positions. The zinc atom is three-coordinate, being surrounded by the tungsten atom and the chelating dimethylaminopropyl group; there is, however, a short intermolecular contact between zinc and a carbonyl oxygen atom at 2.61(3) A.

Crystal structure and reactivity of C4Ph4TiCl3·Mg2Cl3(THF)6, a new type of organometallic complex

Reaction of TiCl3·3THF, diphenylacetylene and i-PrMgCl yields a blue complex of composition C4Ph4TiMg2Cl2·6THF. The complex is very sensitive to moisture. An X-ray diffraction study has shown that it consists of an ion pair (C4Ph4TiCl3)−, containing a planar cyclobutadiene ring, and (Mg2Cl3·6THF)+, in which the magnesium atoms are octahedrally surrounded by three bridging chlorine atoms and three disordered THF molecules.

Caesium–Lithium Phyllosilicate, Cs1.33Li0.67Si2O5

The crystal structure of a (Cs,Li) phyllosilicate with composition Cs 1.33 Li 0.67 Si 2 O 5 has been characterized by a single-crystal X-ray diffraction study. Its silica sheet is exceedingly tortuous with a four-eight-twelve-membered ring topology and a large variation in bridging-oxygen number density in the sheet, thus differing from the six-membered ring topology of Li phyllosilicate and the four-eight-membered ring topology in Cs and Rb phyllosilicate. The title compound lacks the characteristic sandwich structure of sheet silicates. It resembles a three-dimensional network in which Si atoms are replaced by strictly threefold O-coordinated Li atoms which form flat sheets at ca y = 0 and y = 1/2 with seven- to twelvefold O-coordinated Cs atoms between the silica-lithium sheets at y = 1/4 and y = 3/4. The Cs atoms recur in two types of honeycomb tunnels parallel to the b axis.

Chlorobis{2-[(dimethylamino)methyl]phenyl-C1,N}(pyridine)vanadium(III)

The octahedral coordination of the tervalent bis-aryl vanadium complex [VCl(C5H5N)(C9H12N)(2)] is completed by one pyridine and one Cl ligand with a V-Cl distance of 2.395 (2) Angstrom.

CRYSTAL-STRUCTURE OF THE NOVEL COMPOUND (1-ALPHA, 3-BETA, 5-ALPHA)-1,3-DIPHENYL-5-HYDRIDO-5-ISOPROPOXY-1-LAMBDA-6,3-LAMBDA-6,2,4,6,5-LAMBDA-5-DITHIATRIAZAPHOSPHORINE-1,3-DIOXIDE - A COMPARISON WITH RELATED STRUCTURES

Abstract The title compound (1α, 3β, 5α)-(NSOPh)2NP(H)O-i-Pr crystallizes in the spacegroup P21/n with cell dimensions: a = 12. 150(2), b = 8.911(1), c = 17.614(3) A, β = 107.52(1)o; Z = 4. The structure was solved by direct methods and refined by least-squares techniques to an R value of 0.048 for 2420 independent reflections (collected at room temperature) with I > 2.5 σ(I). The unit cell contains dimeric units which are formed by unprecedented P[sbnd]H…O[dbnd]S bridges. The conformation of the inorganic ring skeleton can be described as a boat; phosphorus and sulfur atoms show a distorted tetrahedral geometry. The S[sbnd]N bond lengths differ slightly, ranging from 1.547(3) to 1.588(2) A. The exocyclic bond lengths are P[sbnd]H = 1.34(2), P[sbnd]O = 1.553(2), S[sbnd]O = 1.439(2) (mean value), and S[sbnd]C = 1.767(4) (mean value) A. From a comparison with analogous structures the degree of asymmetry (ΔI = {[P[sbnd]N]-[S[sbnd]N]}A) in the SNP unit is related to the difference in electronegativity between...