Isolation of [{HB(Me2pz)3}MoO2(OC6H4S)]2, a binuclear Mo(VI) complex containing a disulfide bond

Aerial recrystallization of the mononuclear molybdenum(V) complex {HB(Me₂pz)₃}MoO(OC₆H₄-o-S) produced the novel binuclear Mo(VI) complex [{HB(Me₂pz)₃}MoO₂(OC₆H₄- o-S)]₂ which contains a disulfide bond. The dimer crystallizes as the dioxane solvate in the space group C2/c with cell parameters a=23.46(2), b=11.100(4), c=21.571(8) Å, β=104.23(4)°, Z=4. Final R_w=0.062 (2236 reflections with F_o>3σ(F_o), 301 variable parameters). The dimer contains two crystallographically identical distorted octahedral MoO₂²⁺ centers. One face of each octahedron is occupied by two oxo ligands and a phenolate oxygen atom; the opposite face is occupied by three nitrogens of the HB(Me₂pz)₃⁻ ligand. The two Mo(VI) centers of the dimers are linked by a disulfide bond formed upon oxidation of the 2-mercaptophenolate ligand of the original molybdenum(V) compound.     

95Mo NMR spectra of MoO2(C8H7N2S)2 and X-ray crystal structure of Mo2O4(C8H7N2S)2(C3H7NO)2

The facile preparation of MoO₂(C₈H₇N₂S)₂ is given and its complex behaviour in dimethylformamide, as revealed by ⁹⁵Mo NMR spectroscopy, discussed. The X-ray crystal structure of one of the products obtained from this dimethylformamide solution is briefly described. This structure indicates that the Mo(VI) has been reduced to Mo(V) and is based on the [Mo₂O₄]²⁺ core.     

Structural chemistry of dicyclopentadienidehalides of lanthanides Part 4. Erbiumdicyclopentadienidechloride [Er(C5 H5)2Cl]2

The crystal structure of erbiumdicyclopentadienidechloride [Er(C₅H₅)₂Cl]₂ has been determined from X-ray diffraction data. The compound crystallizes in space group P2₁/c with a=11.056(3), b= 8.015(1), c=12.154(3) Å, β=110.28(2)°, V= 1010.2(7) ų, D_c=2.189 g cm⁻³ and Z=2 dimers. The structure has been refined by full-matrix least- squares techniques to a conventional R factor of 0.027 for 2042 reflections (with I > 2σ(I)). In the unit cell centrosymmetric dimers of orte type exist with bridging chlorine atoms and C₅H₅ groups bonded in η⁵-fashion to the metal (mean ErC 2.59 Å). The [Er(C₅H₅)₂Cl]₂-type is compared to the [Sc(C₅H₅)₂Cl]₂-type structure which is realized in several dicyclopentadienidebromides of the lanthanides.     

95Mo NMR studies of complexes containing the Mo2O52+ core and crystal structure of Mo2O5[SC6H4NHCH2C5H4N]2(C3H7NO)3

The crystal structure of Mo₂O₅[SC₆H₄NHCH₂C₅H₄N]₂(C₃N₇NO)₃ is reported and seen to consist of a single oxo-bridged species with each Mo atom bonded to cis dioxo groups and the nitrogen atoms and thiolate group of the tridentate ligand. ⁹⁵Mo NMR spectra of this and three related complexes are presented and attempts made to interpret them in terms of their crystal structures.     

Crystal structure of bis(pyrrole-N-carbothioate)bis(triphenylphosphine)nickel(II), C46H38N2S2P2Ni

The crystal structure of Ni(C₄H₄NCOS)₂[(C₆H₅)₃P]₂, Ni(ptc)₂(Ph₃P)₂, has been determined by single crystal X-ray diffraction methods. This species exists as a square planar complex. The structure is monoclinic, P2₁/n, a=12.759(4), b=10.069(2), c= 16.158(6) Å, and β=91.96(3)°. The unit cell contains 2 formula units with an observed density of 1.31 g cm⁻³ (1.34 calculated). The final R index= 0.047 (R_w=0.038) for 2618 non-zero reflections having I > 3 σ(I).     

Synthesis,properties and structure of hexaaquo-tris(N,N-dimethylformamide)-lanthanide trifluoromethanesulfonates

The compounds of general formula [Ln(DMF)₃- (H₂O)₆](CF₃SO₃)₃ (Ln = LaEu, Tb, Dy) were synthesized and characterized by microanalysis, conductance measurements, IR absorption (Nd³⁺) and emission (Eu³⁺) spectra. The crystal structure of the neodymium compound was determined by X-ray diffraction techniques. The compound crystallizes in the triclinic system, space group P1, a = 8.589(4), b = 11.222(2), c = 12.271(2) Å, α = 56.83(2), β = 62.13(2), γ = 75.14(2)°, V = 875.2 ų, M = 918.4, Z = 1, D_c = 1.73 g cm⁻³, λ(Mo Kα) = 0.71073 Å, μ = 1.65 mm⁻¹, F(000) = 456, R = 0.056, R_w = 0.057, for 2979 independent reflections with I > 3σ(I). Nd³⁺ is coordinated to the oxygen atoms of six independent water molecules at a mean distance NdO = 2.52(1) Å, and to the oxygen atoms of three independent DMF groups at a mean distance NdO = 2.40(2) Å. The coordination polyhedron is a tricapped trigonal prism of point symmetry C_3v.     

Intramolecular hydrogen bonding: synthesis and crystal structure of nickel(II) and copper(II) complexes of a tetradentate amine oxime

In the reaction of the tetradentate ligand 3,3′-(1,4- butanediyldiamino) bis (3-methyl-2-butanone)-dioxime (BnAO) with nickel(II) and copper(II), the monomeric [Ni(BnAO-H)]I·H₂O and a mixed monomer/dimer salt [Cu(BnAO-H)H₂O]₂[(Cu(BnAO-H))₂](ClO₄)₄, respectively, are formed, and all complexes have an intramolecular hydrogen bond between cis oxime groups. The OHO bonds give the characteristic infrared absorptions as well as the downfield proton-NMR signal (Ni complex). [Ni(BnAO-H)]I·H₂O crystallizes in space group P2₁/a with a=13.511(2), b=10.599(2), c=14.096(2) Å, β=97.52°, Z=4 and D_c=1.623 g/cm³. The structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares techniques to a final R of 0.021 for 2124 reflections with I 2σ(I). The nickel(II) atom in the complex has slightly distorted square planar geometry with an intramolecular O···O contact of 2.417(7) Å. The copper(II) complex crystallizes in space group P2₁/c with a =13.425(2), b=21.446(3), c=14.349(4) Å, β= 104.4(5)°, Z=8 (monomers) and D_c=1.485 g/cm³. The final R value for this complex was 0.053 for 3033 reflections with I 2σ(I). This structure contains a monomeric [Cu(BnAO-H)H₂O]⁺ ion and a dimeric [(Cu(BnAO-H))₂]²⁺ ion, having intramolecular O···O hydrogen bonds of 2.421(5) and 2.531(5) Å, respectively. The copper(II) ions have square-pyramidal coordination with the axial positions occupied by an oxygen of the water of hydration in the monomer and by an oxime oxygen atom in the dimer. A center of symmetry relates the two halves of the dimer. The copper atom in each case is out of the plane of the four nitrogen atoms toward the axial site. The copper(II) complex is unusual in that the crystal contains both a monomer and a dimer.     

Synthesis,structure, reactivity and electrochemistry of a new molybdenum(0) dithiocarbamato complex, [Et4N][Mo(CO)4(S2CNEt2)]

A new molybdenum(0) dithiocarbamato complex [Et₄N] [Mo(CO)₄(S₂CNEt₂)] (1) has been synthesized by the reaction of Mo(CO)₆, NaS₂CNEt₂ and Et₄NCl in MeCN and characterized by routine elemental analysis, spectroscopy methods. The crystal and molecular structure of 1 was determined from X-ray three dimension data. 1 crystallizes in the orthorhombic, space group Pbc2₁ with a= 8.148(2), b=19.618(2), c=14.354(2) Å; V=2294 ų; Z=4; R₁=0.052, R₂=0.058 for 1308 independent reflections with I ⩾ 3σ(I). The geometry around Mo(0) atom in the anion [Mo(CO)₄(S₂CNEt₂)]^- of 1 is distorted octahedral with a small SMoS of 67.70° and a small angle of 3.6° between plane MoSS and MoC(1)C(2). Two groups of MoCO bond distances and the longer MoS bond distance observed in 1 are similar to that in the dinuclear Mo(0) complexes containing SR bridges but very different from those observed in the dithiocarbamato complexes of Mo in higher oxidation states. Different oxidizing products containing Mo in II-V oxidation states Mo(CO)₂(S₂CNEt₂)₂, MoO(S₂CNEt₂)₂, Mo₂O₃(S₂CNEt₂)₄ and Mo₂O₄(S₂CNEt₂)₂ were isolated from the oxidation of 1 with I₂ (or in the presence of traces of air). The electrochemical behavior of 1 in MeCN was investigated by cyclic voltammetry at Pt and C electrodes. The anodic peaks observed at 0.04, 0.14, 0.26 and 0.44 V versus SCE implied that 1 probably underwent oxidation in company with dissociation of dithiocarbamate and substitution of carbonyls resulting in several complexes of Mo in different oxidation states. The relationship between reactivity and structure is also discussed.     

The crystal and molecular structures of dioxo mo(VI) complexes of tripodal,tetradentate N,S-donor ligands

The crystal and molecular structures of the complexes MoO₂((SCH₂CH₂)₂NCH₂CH₂SCH₃), I and MoO₂((SCH₂CH₂)₂NCH₂CH₂N(CH₃)₂), II, have been determined from X-ray intensity data collected by counter methods. Compound I crystallizes in two forms, Ia and Ib. In form Ia the space group is P2₁/n with cell parameters a = 7.235(2), b = 7.717(2), c = 24.527(6) Å, β = 119.86(2)°, V = 1188(1) ų, Z = 4. In form Ib the space group is P2₁/c with cell parameters a = 14.945(5), b = 11.925(5), c = 14.878(4) Å, β = 114.51(2)°, V = 2413(3) ų, Z = 8. The molecules of I in Ia and Ib are very similar having an octahedral structure with cis oxo groups, trans thiolates (cis to both oxo groups) and N and thioether sulfur atoms trans to oxo groups. Average ditances are MoO = 1.70, MoS (thiolate) = 2.40, MoN = 2.40 and MoS (thioether) = 2.79 Å. Molecule II crystallizes in space group P2₁2₁2₁ with a = 7.188(1), b = 22.708(8), c = 7.746(2) Å, V = 1246(1) ų and Z = 4. The coordination about Mo is octahedral with cis oxo groups, trans thiolates and N atoms trans to oxo. Distances in the first coordination sphere are MoO = 1.705(2), 1.699(2), MoS = 2.420(1), 2.409(1) and MoN = 2.372(2), 2.510(2) Å. The conformational features of the complexes are discussed. Complex I displays MoO and MoS distances which are very similar to those found by EXAFS in sulfite oxidase. This similarity is discussed.     

The structure of a dinuclear silver(I) complex: Ag2[S2C2(CN)2] [P(C6H5)3]4

The crystal structure of the dimeric Ag maleonitriledithiolate complex, Ag₂[S₂C₂(CN)₂] [P(C₆- H₅)₃]₄ (1), has been performed. Complex 1 crystallizes in the space group P2₁/c with a = 12.2898(77), b = 23.8325(91), c = 23.1790(118) Å, β = 101.315(43)° and Z = 4. Refinement using 3253 reflections with F_o²>3σ(F_o²) yielded R = 0.0662, R_w= 0.0669. The most interesting aspect of the structure is the strong bridging interaction of the chelating maleonitriledithiolate ligand with the second Ag center, where a Ag-S distance of 2.478 Å is observed. The residual bonding capability of the sulfur atoms in the chelating anion [Ag(S₂C₂(CN)₂)(PPh₃)₂]⁻ for [Ag(PPh₃)₂]⁺ is demonstrated.     

Structural comparison of octahedral MoO22+ complexes of bidentate and linear tetradentate N,S-donor ligands

The structures of MoO₂[NH₂C(CH₃)₂CH₂S]₂ and MoO₂[SC(CH₃)₂CH₂NHCH₂CH₂NHCH₂C(CH₃)₂S] have been determined using X-ray diffraction intensity data collected by counter techniques. MoO₂[NH₂C(CH₃)₂CH₂S]₂ crystallizes in space group Pbca with a = 11.234(3), b = 11.822(3) and c = 20.179(5) Å, V = 2680(2) ų and Z = 8. Its structure is derived from octahedral coordination with cis oxo groups [MoO = 1.705(3) and 1.705(3)], trans thiolate donors cis to the oxo groups [MoS = 2.416(1) and 2.402(1) and N donors trans to oxo [MoN = 2.325(3) and 2.385(4) Å]. MoO₂[SC(CH₃)₂CH₂NHCH₂CH₂NHCH₂C(CH₃)₂S] crystallizes in the space group P2₁/c with a = 10.798(5), b = 6.911(2), c = 20.333(9) Å, β = 95.20°, V = 1511(2) Å₃ and Z = 4. Its structure is very similar to that of MoO₂[NH₂C(CH₃)₂CH₂S]₂ with MoO = 1.714(2) and 1.710(2), MoS = 2.415(1) and 2.404(1) and MoN = 2.316(3) and 2.362(3). The small differences in the geometries of the two compounds are attributed to the constraints of the extra chelate ring in the complex with the tetradentate ligand. The structures in this paper stand in contrast to those reported for complexes of similar ligands wherein steric hindrance produces complexes with a skew trapezoidal bipyramidal structure.     

A heteronuclear (Pt,Zn) complex of 1-methyluracil with different coordination geometries (square-planar and square-pyramidal) of the two metals

Reaction of cis-(NH₃)₂Pt(1-MeU)₂ (1-MeU = 1- methyluracil anion, C₅H₅N₂O₂) with ZnSO₄·7H₂O leads to the formation of a dinuclear complex of composition [(NH₃)₂Pt(C₅H₅N₂O₂)₂Zn(H₂O)₃]SO₄· 2H₂O. The compound crystallizes in space group P2₁/c with a = 10.534(1), b = 17.933(2), c = 11.490(1) Å, β=94.61(1)°, Z=4. The structure was refined to R=0.043 and R_w=0.061. In this compound, Pt is coordinated through N3 to the 1-MeU ligand, while Zn is bound through the two O4 oxygens and completes its distorted square-pyramidal coordination sphere by three aqua ligands. The positions of the two metals relative to their basal donor atoms and the shortness of the PtZn separation (2.760(1) Å) suggest a bonding interaction between the two metals. Using ¹H NMR spectroscopy, a formation constant of ca. 114 1 mol^?1 for the Pt, Zn complex has been estimated.     

Crystal and Molecular Structure of (+)-Carba-Thymidine,C11 H10 N2 O6

Abstract

The molecular structure of (+)-carba-thymidine possessing notable anti-HSV activity has been determined by single crystal X-ray diffraction. It crystallizes in the monoclinic space group P2 with unit cell dimensions a = 4.810(2), b = 11.560(1)¹, c = 10.014(1) A, β = 92.34(2)°, Z = 2. The structure was solved by direct methods and refined by least squares to a final R = 0.038 for 1027 reflections (I < 36(I)). The torsion angle x around the glycosidic N1-C1′ bond agrees with that of thymidine (37.5°vs 39.1°) whereas the C3′-exo pucker of the five-membered ring is shifted to an even less common C1′-eao form.     

Metal—phenoxyalkanoic acid interactions. Part 14. The crystal and molecular structures of diaquabis(4-fluorophenoxyacetato)copper(II) bis(4-fluorophenoxyacetic acid)dihydrate and tetra-μ-(4-fluorophenoxyacetato-0,0′)-bis[(2-aminopyrimidine)copper(II)]

The crystal structures of two copper(II) complexes of 4-fluorophenoxyacetic acid (4-FPAH) have been determined by X-ray diffraction. [Cu(4-FPA)₂(H₂O)₂]·2(4-FPAH)·2H₂O (1) is triclinic, space group P1 with Z = 1 in a cell of dimensions a = 14.808(2), b = 9.832(2), c = 6.847(2) Å, α = 87.77(2), β = 98.41(2), γ = 112.33(2)° and was refined to a residual of 0.038 for 1697 ‘observed’ reflections. The coordination sphere in this complex is tetragonally distorted octahedral comprising two waters [CuO, 1.940(3) Å], two unidentate carboxylate oxygens [CuO, 1.942(2) Å] and two ether oxygens [CuO, 2.471(2) Å]. Two adducted [4-FPAH] acid molecules are linked to the un-coordinated oxygens of the acid ligands by hydrogen bonds [2.547(4) Å]. [Cu₂(4-FPA)₄(2-aminopyrimidine)₂] (2) is triclinic, space group P1 with Z = 1 in a cell of dimensions a = 12.688(2), b = 11.422(2), c = 7.951(1) Å, α = 78.74(1), β = 107.51(1), γ = 75.78(1)°, and was refined to a residual of 0.042 for 2683 ‘observed’ reflections. (2) is a centrosymmetric tetracarboxylate bridged dimer with four similar CuO (equatorial) distances [1.967–1.987 Å; 1.977(3) Å mean] and the axial position occupied by the hetero nitrogen of the 2-aminopyrimidine ligand [CuN, 2.176(3) Å]. The Cu---Cu separation is 2.710(1) Å. Crystal data are also presented which confirm the isostructurality of complex (2) with [Cu₂(phenoxyacetate)₄(2-aminopyrimidine)₂], the Co^II, Mg^II and Mn^II4-fluorophenoxyacetate complexes with their phenoxyacetic and 4-chlorophenoxyacetic acid analogues, and of Cd^II4-fluorophenoxyacetate with Cd^II and Zn^II phenoxyacetates.     

The hydrogen bonding effect on the halobismuthate(III) geometry: thermal,spectroscopic and structural properties of halobismuthate complexes of 4,6-dimethylpyrimidine-2(1H)-thione

Reactions involving Bi(III) halides and 4,6- dimethylpyrimidine-2(1H)-thione (L) in HX solution result in the formation of [HL]₃[BiX₆]·2H₂O (X=C1, Br) and [HL]₃[Bi₂I₉]. These compounds together with the organic molecule in the form of the hydrochloride, (HLCl) were characterized by means of spectroscopic and thermogravimetric measurements. For HLCl·H₂O (1) and [HL]₃[BiCl₆]·2H₂O (2), X-ray structures were determined. In 1, which crystallizes in the space group Pca2₁, with four molecules in the cell, the structure consists of roughly planar protonated organic molecules stacked along the [100] axis and built up by hydrogen bonds involving chlorine atoms and water molecules. For 2, the space group is P2₁/n, Z=4, the structure contains [BiCl₆]³⁻ anions, protonated organic molecules stacked along the [010] axis and water molecules which form strong hydrogen bonds with the [BiCl₆]³⁻ anions. The final R indices are 0.0320 and 0.0465 for 1 and 2, respectively.     

Preparation,crystal structure and thermal behaviour of bischromatodihydroxobis-(pyridine)tricopper(II) [Cu3(CrO4)2(OH)2(C5H5N)2]

The title compound was prepared by slow crystallization from a hot aqueous solution of copper(II)- dichromate and pyridine. The structure determination was performed at room temperature on a single crystal in the triclinic space group P$\text{1}$, a = 5.378(1), b = 5.619(1), c = 13.569(2) Å, α = 93.32(1), β = 100.25(1), γ=98.45(1)°. Using 2026 reflections with F_o² > (F_o²) obtained on a CAD-4 single crystal diffractometer the structure was solved by conventional Patterson and Fourier methods and full matrix least-squares refinement to R = 0.047. The structure consists of complex chains built up from two different (4 + 2) distorted copper(II) octahedra sharing common edges. These chains are linked via OCrO bonds thus forming a two-dimensional infinite network. The pyridine rings extending into the space between these layers are disordered due to rotation around the CuN bond. In the course of the refinement two favoured positions with occupation probabilities 50:50 percent were found. During thermal decomposition the compound loses pyridine and water followed by a release of oxygen to yield poly- crystalline CuCr₂O₄ and CuO. An intermediate phase with empirical formula Cu₃O(CrO₄)₂ was detected by X-ray powder diffraction and its unit cell parameters were determined.     

Synthesis and crystal structure of (pipzH2)2Mo2Cl8·4H2O (pipz = piperazine)

The title compound (pipzH₂)₂Mo₂Cl₈·4H₂O (pipz = piperazine),was isolated from the solution of (morphH)₂Mo₂Cl₆(H₂O)₂ in HCl 1:1 by addition of (pipzH₂)Cl₂. This reaction indicates the reversibility of the substitution of chloride ions in Mo₂Cl₈^4? by water molecules. (pipzH₂)₂Mo₂Cl₈·4H₂O crystallizes in the Pbca space group, with a = 15.154(2), b = 13.170(2), c = 12.208(2) Å and Z = 4. The structure was solved by the Patterson method and refined to the unweighted and weighted residuals of 0.050 and 0.048. The crystal structure is built form Mo₂Cl₈^4?, (pipzH₂)²⁺ and H₂O. The MoMo distance of 2.129(3) Å is the shortest one found in all structurally-characterised Mo₂X₈^4? (X = Cl, Br) anions. Four independent MoCl distances are 2.456(3), 2.445(3), 2.463(4) and 2.455(4) Å. The (pipzH₂²⁺ exists in a usual chair conformation. There is a network of hydrogen bonds of the type NH?Cl, NH?O, OH?Cl and OH?O between the ions and water molecules.     

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.