The crystal and molecular structures of tris(O-ethylxanthato)-gallium(III) and indium(III)

The crystal structures of the title compounds, Ga(S₂COEt)₃ (1) and In(S₂COEt)₃ (2) have been determined by three dimensional X-ray diffraction methods. Both compounds crystallize in the trigonal space group R with Z = 6. Cell dimensions for (1) are a_hex 15.065(1) and c_hex 13.421(1) Å and for (2) 15.319(3) and 13.522(4) Å. Final R. and R_w values 0.044 and 0.049 for (1) and 0.040 and 0.037 for (2) for 668 and 1153 statistically significant reflections respectively.The complexes are isostructural. The metal centres are in a distorted octahedral environment, the distortion arising from the restricted bite distance of the xanthate ligands. For each compound, each xanthate moiety chelates the metal atom with similar M-S bonds.     

The crystal and molecular structure of diethylenetriammonium hexachloro-antimonate(III)

A compound of the type [DenH₃]SbCl₆ (DenH₃ = diethylenetriammonium cation) was prepared and characterized by means of structural and vibrational measurements. The structure consists of monomeric SbCl₆^3? anions and triprotonated diethylenetriam-monium cations. The SbCl₆^3? anion has a strongly distorted octahedral geometry, presenting three short (2.415–2.495 Å) and three long (2.836–3.114 Å) SbCl bonds. The presence of multiple hydrogen bonds, mainly involving the counterion and the three long-bonded chlorine atoms, is considered to be responsible for the octahedral distortion. Vibrational properties of the complex are discussed in the light of its known crystal structure.     

Structural features of group V A xanthates. The crystal and molecular structures of tris(O-isopropylxanthatoarsenic(III), antimony(III) and -bismuth(II)

The crystal structures of the title compounds, M(S₂COⁱC₃H₇)₃, M = As(III), (1); Sb(III), (2); and Bi(III), (3) have been determined by three dimensional X-ray diffraction techniques and refined by a least square method. Crystals of (1) and (2) are isomorphous and both crystallize in the rhombohedral space group R$\text{3}$, with unit cell parameters for (1) a_hex = 11.559(2), c_hex = 28.131(3) Å and for (2) a_hex = 11.696(2) and c_hex = 28.135(2) Å, Z = 6. The central metal atom in both (1) and (2) is coordinated by three asymmetrically chelating xanthate ligands [AsS 2.305(2) and 2.978(2) Å and SbS 2.508(1) and 3.006(1) Å] which form a distorted octahedral environment consistent with the presence of a stereochemically active lone pair of electrons. Crystals of (3) are orthorhombic, space group Pnma, Z = 4 with dimensions a = 11.003(3), b = 20.833(4) and c = 9.428(2) Å. The environment of the bismuth atom in (3) is seven coordinate and is comprised of six sulphur atoms, derived from three asymmetrically coordinating xanthate ligands, and a bridging sulphur atom from a neighbouring molecule which results in the formation a polymeric array. For (1) final R and R_W 0.050 and 0.047 respectively for 936 reflections [I ? 3σ(I); (2) R 0.040, R_w 0.040 for 1455 reflections I ? 2σ(I)]; and (3) R 0.052, R_w 0.039 for 1796 reflections [I ? 2σ(I).     

Crystal and molecular structure of tris(propane-1,3-diamine)nickel(II) dinitrate complex

The title compound, [Ni(1,3-pn)₃](NO₃)₂, crystallizes in the orthorhombic space group Pbca with eight formula units in a cell of dimensions a = 17.146(8), b = 14.364(5) and c = 15.054(7). The structure was solved by the heavy-atom method and refined by least-squares calculations to R = 0.053 for 1439 counter data. It consists of discrete, slightly distorted octahedral [Ni(1,3-pn)₃]²⁺ cations and NO₃^? anions. One of the three six-membered chelate rings show a pronounced flattening unusual chair conformation. Magnetic and spectroscopic data agree to a lower stability of six-membered chelate rings, compared to five-membered chelate ones.     

The effect of pressure on the photochemistry of tris(bipyridyl)chromium(III) ion

The quantum yield for the photoaquation of Cr(bpy)₃³⁺ in basic medium decreases with increasing pressure, with an apparent volume of activation of 3.8 ± 1.0 ml mol⁻¹. From this value and that associated with the phosphorescence lifetime, the volumes of activation for non-radiative decay to the ground state and for formation of photoproduct are derived as −1.6 and +2.9 ml mol⁻¹, respectively. The latter value is consistent with either an associative process with water entering from pockets between the ligands or a dissociative process involving one or both bonds to a bipyridyl ligand.     

The copper(II) catalyzed reaction of L-ascorbinc acid with tris(oxalato)cobaltate(III) ion in aqueous solution

The kinetics of the reaction between tris(oxalato)cobaltate(III) ion and L-ascorbic acid were studied in aqueous solution over a range of copper(II) ion concentrations, ascorbic acid concentrations, pH values and temperatures. A rate law of the type rate = k[HA^?][Cu²⁺][Co³⁺], where HA^? = ascorbate, is suggested by the experimental results. A mechanism involving a copper-ascorbate complex is proposed.     

Synthesis and characterization of nitroimidazole complexes of platinum and palladium and the crystal and molecular structure of trans-dichlorobis(misonidazole)platinum(II)

The synthesis and properties of some nitroimidazole complexes of platinum and palladium starting from the MCl₄^2- salts are described. Both 5-NO₂-imidazole and metronidazole give cis-[MCl₂L₂] complexes whereas trans-[MCl₂L₂] is obtained for 2-NO₂-imidazole and misonidazole. The crystal structure of trans-dichlorobis(misonidazole)platinum(II) was determined by three-dimensional X-ray methods. The compound crystallized in space group P2₁/c in discrete monomeric units with a = 11.303(5), b = 13.002(5) and c = 8.125(3) Å, B = 91.39(3)°, Z = 2 and the observed and calculated densities are 1.83 and 1.859 respectively. The final full-matrix least-squares refinement gave values of R₁ = 0.037 and R₂ = 0.045 for 142 variables. The complex is square-planar with Pt-Cl and Pt-N distances of 2.294(3) and 2.016(9) Å respectively. The mean plane of the misonidazole ring is twisted 56° with respect to the PtCl₂L₂ square plane and the Cl-Pt-N angles are 89.4(3) and 90.6(3)°; the nitro group also lies out of the plane of the misonidazole ring. The closest nonbonded contact between non-hydrogen atoms in the unit cells is 2.80 Å suggesting hydrogen bonding between the hydroxyl proton and the ether oxygen in the misonidazole side-chain, i.e. O-H?O. Aspects of the chemistry of these species in relation to their biological activity are discussed.     

Preparation and crystal structure of bis(acetato)(trans-1,2-diaminocyclohexane)platinum(II)

The structure of the complex [Pt(trans-1,2-di- aminocyclohexane) (acetate)₂]·H₂O has been determined by X-ray diffraction. This racemic compound is orthorhombic, space group Aba2, a = 20.813(9), b = 7.926(5), c = 17.296(8) Å, Z = 8. The structure was refined on 1214 nonzero Cu Kα reflections to R = 0.028. The square planar environment of Pt includes the amino groups of the diamine in cis positions and oxygens from two monodentate acetates. The PtN and PtO distances average 2.00(3) and 2.02(3) Å, respectively. The bite of the diamine ligand imposes a NPtN angle of 85(1)°, whereas the small OPtO angle of 85(1)° probably results from packing effects. The average plane through the puckered cyclohexyl ring makes an angle of 19° with the PtN₂O₂ plane. The molecules are stacked by pairs along the b axis. The two molecules of each pair are 180° apart about the stacking axis, and form altogether four NH···O hydrogen bonds.     

Synthesis and crystal and molecular structure of a methyl N,N-diethylcarbamylmethylenephosphonato dysprosium thiocyanate complex

Bis-Methyl N,N-diethylcarbamylmethylenephosphonato dysprosium thiocyanate, Dy[O₂P(OCH₃)CH₂C(O)N(C₂H₅)₂]₂(NCS) was prepared from the combination of ethanolic solutions of Dy(NCS)₃·xH₂O and (CH₃O)₂P(O)CH₂C(O)N(C₂H₅)₂. The complex was characterized by infrared and NMR spectroscopy, and single crystal X-ray diffraction methods. The crystal structure was determined at 25 °C from 3727 independent reflections by using a standard automated diffractometer. The complex was found to crystallize in the monoclinic space group P2₁/c with a = 13.282(4) Å, b = 19.168(5) Å, c = 9.648(2) Å, β = 90.09(2)°, Z = 4, V = 2456.4 ų and ?_cald = 1.72 g cm^?3. The structure was solved by standard heavy atom techniques, and blocked least-squares refinement converged with R_f = 4.7% and R_wF = 4.9%. The Dy atom is seven coordinate and bonded in a bidentate fashion to two anionic phosphonate ligands [O₂P(OCH₃)CH₂C(O)N(C₂H₅)₂^?] through the carbonyl oxygen atoms and one of two phosphonate oxygen atoms. In addition, each Dy atom is coordinated to two phosphonate oxygen atoms from two neighboring complexes and to the nitrogen atom of a thiocyanate ion. This coordination scheme gives rise to a two-dimensional polymeric structure. Some important bond distances include DyNCS 2.433(8) Å, DyO(carbonyl)_avg 2.39(2) Å, DyO(equat. phosphoryl)_avg 2.303(8) Å, DyO(axial phosphoryl)_avg 2.25(2), PO(phosphoryl)_avg 1.493(3) Å and CO(carbonyl)_avg 1.25(1) Å.     

Interaction of metal ions with humic-like models. Part 5. The crystal and molecular structure of diaquabis(2,6-dihydroxybenzoato)-dioxouranium(VI) octahydrate

The crystal and molecular structure of the complex [UO₂(DHB)₂(H₂O)₂]·8H₂O (DHB = 2,6-di- hydroxybenzoato) has been determined from single- crystal X-ray analysis and refined to a final R value of 0.033 for 3620 observed reflections. The complex crystallizes in the monoclinic system, space group C2/m, with a = 6.704(3), b = 20.171(6), c = 9.454(4) Å and Z = 2. The coordination about the uranyl group, which is linear, involves two bidentate carboxylate groups and two water molecules in trans positions giving rise to an irregular hexagonal bipyramid. Intra- molecular hydrogen bonds between phenolic and carboxylate groups forming six-membered rings allow the molecule to be nearly planar. Spectroscopic (IR, NMR and electronic absorption) data and thermal properties of the compound are also reported.     

The structure of 1,3-diphenyl-1,3-propandionatobis(triphenylantimony)diphenylrhodium(III)dibenzene

1,3-Diphenyl-1,3-propandionatobis(triphenylantimony)diphenylrhodium(III)dibenzene, [Rh(DPD)(SbPh₃)₂Ph₂]·2(C₆H₆) has been isolated as the product of the reaction between the Rh(I) complex 1,3-diphenyl-1,3-propandionatodicarbonylrhodium(I), [Rh(DPD)(CO)₂], and triphenylantimony in acetone and in n-hexane medium. The crystal and molecular structure was determined from single crystal X-ray diffractometer data. The unit cell is triclinic with a = 19.083, b = 13.167, c = 13.536 Å, α = 81.81°, β = 111.59°, γ = 100.49°, Z = 2 and space group P_$\text{1}$. The structure was refined to a R-value of 0.079 for 6637 contributing reflections. The coordination polyhedron can be described as a slightly distorted octahedron in which the Rh-atom is coordinated by two phenyl groups, two oxygen atoms of a chelate ring, which are in cis position to one another, and two antimony-atoms of the two SbPh₃ ligands, which are in trans positions.     

Synthesis and x-ray crystal structure of a tin(IV) tetrahalide adduct with a crown ether

The polymeric structure of the complex, [SnCl₄(H₂O)₂]18-crown-6·2H₂O, prepared by the addition of a solution of SnCl₄ to 18-crown-6, has been determined by X-ray analysis. The structure has been solved by three-dimensional Patterson-Fourier synthesis to a conventional R-factor of 0.13, by using 1394 reflections with I>3σ(I). The crystals are monoclinic, with a = 15.753(3), b = 15.072(3), c = 12.209(4), β = 97.77°(1.0), z = 4, and space group P2_1/^a. The tin atom is octahedrally coordinated to four chlorine atoms and two water molecules in cis positions. A very complex network of hydrogen bonding links together the tin coordination octahedron, the two water hydration molecules, and the two crystallographically-different half crown-ethers.     

The preparation,spectral studies,and the crystal structure of dimethylbis(O-ethylxanthato)tin(IV)

Tin-119 NMR data indicate that the tin atom in (CH₃)₂Sn(S₂COC₂H₅)₂ is four co-ordinated in dichloromethane solution. However, single crystal X-ray analysis shows the tin atom to be six co-ordinated in the solid state in which the bidentate xanthate ligands display gross asymmetry in their mode of co-ordination to the tin. The crystals are molecular and there is no association between neighbouring molecules. The unit cell of Me₂Sn(exa)₂ is orthorhombic, Pnma, a = 14.165(1), b = 7.675(9), c = 13.977(2) Å with Z = 4. The structure was refined by conventional least squares methods with final R 0.041 and R_w 0.043 for 1229 unique reflections with 1 ? 2σ(I).     

The preparation and crystal structure analysis of a 2:1 complex between L-lysine and copper(II) chloride

The crystal structure of bis(L-lysine)Cu(II) chloride dihydrate has been determined by X-ray analysis. The complex crystallizes in the monoclinic space group P2₁, with cell dimensions a = 5.189(1), b = 16.988(3), c = 11.482(2) Å, β = 93.57(1)°. The position of the Cu atom was found from a Patterson synthesis, the remaining atoms were located with DIRDIF. The structure was refined by least-squares to R = 0.060 and R_w = 0.065 for 2637 observed reflections. The copper(II) atom has an essentially square planar coordination with the two lysine molecules chelated via the carboxy oxygen and the α-amino nitrogen. However the two chlorine atoms form weak interactions with the metal to complete a strongly tetragonally elongated six-fold coordination. The two aliphatic chains have rather different geometries and are extended in a zig-zag mode. Extensive hydrogen bonding links the complex and the water molecules together.     

The crystal and molecular structure of [Co(NH3)5PO4]·3H2O,a Na+-K+ ATPase probe

The title compound, Co(NH₃)₅PO₄, prepared by a modified literature procedure, was used to study the inhibition of Na⁺-K⁺ ATPase and to serve as a structural model for ML₄(nucleotide) complexes. The structure was determined by single crystal X-ray diffraction techniques. The crystals are monoclinic, space group P2₁/n, a = 8.638(3), b = 14.517(2), c = 9.145(2) Å, and β = 112.71(2)°. The structure, solved by the heavy atom method to an R value of 3.3% for 1924 reflections, consists of a slightly distorted octahedron with the cobalt bound to the five amines and a monodentate phosphate. Solution structural data is taken from ³¹P NMR measurements. From comparison with other metal phosphate complexes it is concluded that multiple monodentate coordination of a di- or triphosphate closely resembles the coordination of a monophosphate This is based on the similarity of the MO bond angle which is 129.6° in the present example.     

Light-induced electron-transfer reactions. Part 2. Kinetics of the intra-molecular redox decomposition of tris(oxalato)-cobaltate(III) by irradiation with visible light of aqueous solution containing tris(2,2′-bipyridine)ruthenium(II) ion

The rate of the intra-molecular redox decomposition of the tris(oxalato)cobaltate(III) ion [Co(Ox)₃]^3? is greatly accelerated by irradiation with visible light of aqueous acidic solutions containing the tris(2,2′-bipyridine)ruthenium(II) ion [Ru(bpy)₃]²⁺. The rate of the light-induced reaction in hydrochloric acid with an acidity range 0.05–0.18 mol dm^?3 is of zero-order with respect to the [Co(Ox)₃]^3? ion concentration and is proportional to the light-intensity irradiated and also essentially to the [Ru(bpy)₃]²⁺ ion concentration. Moreover, the rate is independent not only of the oxalate ion concentrations, but also of the acidity over the range 0.05–0.18 mol dm^?3 hydrochloric acid. The ionic-strength dependence, as well as temperature dependence, were extremely small. The [Ru(bpy)₃]²⁺ concentration does not change during the occurrence of the reaction and the tris(2,2′-bipyridine)ruthenium(II) ion acts as a homogeneous catalyzer. However, a dramatic indication that the situation was rather different was found in the stronger acid solutions of 0.5 or 1.0 mol dm^?3 hydrochloric acid, in which the [Ru(bpy)₃]²⁺ concentration decreased greatly immediately after the initiation of reaction and then increased up to the initial concentration. Such a decrease at the initial stage of the reaction disappeared by addition of oxalate before the start of the reaction. A chain mechanism of reaction is proposed to account for these results.     

Trans-bis(benzo(1,3)-thiazole)bis(N,N-dimethylformamide)bis(N-thiocyanato)-cobalt(II): spectroscopy,thermal analysis and crystal structure

Disolution of Co(bzt)₂(NCS)₂ (bzt = benzo 1,3- thiazole) in dimethyl formamide (dmf) produces Co(bzt)₂(NCS)₂(dmf)₂. The stoichionmetry of the complex has been established by a combination of chemical (C, H, N) and thermal analysis. The comlex has an octahedral structure with pairs of ligands in trans configuration as well as a CoN₄O₂ coordination sphere with CoN distances of 2.185(2) Å (bzt); 2.082(2) Å (NCS) and CoN(dmf) of 2.118(2) Å. The infrared and electronic absorption spectra are consistent with this arrangement.     

Synthesis and optical study of Ln(III)(tetramethylurea)(AsF6)3 (Ln = LaLu,Y) and crystal structure for Ln = Eu [Eu(TMU)6(AsF6)3]

The fluorescence spectrum of Eu³⁺ recorded at a temperature of 12 K between 14.000 and 20.000 cm^?1 shows transitions from the excited stare ⁵D_o to the Stark components of the lowest ⁷F_j. The optical analysis suggests an octahedral site symmetry for the rare earth ion which is confirmed by the three-dimensional crystal determination. The highly disordered crystal structure refined in space group F23 to an R-factor of 13.2%. Both the europium and the arsenic ions are located in special positions of point symmetry 23(T). The EuO bond distance is 2.28 Å. The value of the B_q^k parameters was determined.