Showing papers by "Alexander J. Blake published in 1999"

Solvent control in the synthesis of 3,6-bis(pyridin-3-yl)-1,2,4,5-tetrazine-bridged cadmium(ii) and zinc(ii) coordination polymers

Abstract: The reaction of cadmium(II) and zinc(II) salts with 3,6-bis(pyridin-3-yl)-1,2,4,5-tetrazine (3,3‘-pytz) affords coordination polymers, the structures of which are controlled by the choice of alcoho...

Controlling copper(I) halide framework formation using N-donor bridging ligand symmetry: use of 1,3,5-triazine to construct architectures with threefold symmetry

Abstract: The formation of co-ordination polymers between copper(I) halides and 1,3,5-triazine (tri), a potentially tridentate N-donor bridging ligand with threefold symmetry, has been studied. Complexes with both 3∶1 and 2∶1 molar ratios are formed by both CuBr and CuI. The compounds [Cu3X3(tri)]∞ (X = Br or I) are structurally similar, despite crystallising in different space groups. They are composed of (CuX)∞ columns linked by triazine molecules to generate three-dimensional constructions with non-crystallographically imposed threefold symmetry. The (CuX)∞ columnar motif can be described as a series of perpendicularly stacked Cu3X3 chairs, alternately rotated by 60° and linked by Cu–X contacts. The tetrahedral co-ordination geometry of the copper centres is completed by a tridentate triazine bridge which links two copper atoms in separate columns. Thus, each (CuX)∞ column is linked to six adjacent (CuX)∞ columns. The structure of [Cu2Br2(tri)]∞ comprises (CuBr)∞ columns and castellated (CuBr)∞ chains linked by triazine molecules to generate a construction with crystallographically imposed threefold symmetry. The (CuBr)∞ columns are similar to but more regular than those found in [Cu3Br3(tri)]∞. In this case, however, each column is linked to six adjacent chains. The (CuBr)∞ castellated chain motif is very unusual. The tetrahedral copper centres are co-ordinated by two adjacent bromide anions and by two triazine molecules each of which links a second chain and a column. Consequently, each chain is linked to four neighbouring chains and two neighbouring columns. Despite a stoichiometry identical to that of [Cu2Br2(tri)]∞, [Cu2I2(tri)]∞ has a completely different structure. The triazine molecules act as bidentate bridging ligands to link (CuI)∞ layers thereby giving alternating inorganic and organic layers. The tetrahedral co-ordination geometry of the copper centres in the (CuI)∞ layers, which are effectively undulating hexagonal nets, is provided by three iodide anions from the layers and by a bridging triazine molecule.

Template Assembly of Metal Aggregates by Imino-Carboxylate Ligands.

Abstract: Lanthanide, main group, and transition metal ion templates provide different polynuclear cages from [M(L)] (M=Ni, Mn; (L)2-=CH2[CH2N=C(CH3)COO-]2). Templating with lanthanum results in a 12-coordinate LaIII ion encapsulated by six [Ni(L)] units, whereas with sodium four Na+ ions are trapped inside a tricapped trigonal prismatic [{Ni(L)}9] cage. With manganese, an octahedrally coordinated MnII ion is surrounded by six [Mn(L)] fragments in a twisted trigonal-prismatic configuration (see picture).

Parallel interpenetration in novel herringbone sheets formed by Co(II) and Cd(II) complexes with trans-4,4′-azobis(pyridine)

Abstract: The complexes {[M2(µ-4,4′-apy)3(NO3)4]·CH2Cl2}∞ (1, M=Co; 2 M=Cd; 4,4′-apy=trans-4,4′-azobis(pyridine)) form interpenetrated 2-D grids with a (6,3) topology. These sheets exhibit a new herringbone motif in which Co(II) or Cd(II) centres are bridged by co-ordinated 4,4′-apy ligands.

Cycloaddition reactions of titanium and zirconium imido, oxo and hydrazido complexes supported by tetraaza macrocyclic ligands‡

Abstract: The tetraaza macrocycle-supported titanium and zirconium imido complexes [Ti(NR)(Mentaa)] [R = But, Ph, Tol or 4-C6H4NO2; n = 4 or 8 where H2Mentaa = tetra- or octa-methyldibenzotetraaza[14]annulene, respectively] and [Zr(NC6H3Pri2-2,6)(py)(Me4taa)] react with isocyanates or carbon dioxide to form cycloaddition products generally of the type [M{N(R)C(O)E}(Mentaa)] (M = Ti or Zr, R = aryl or tert-butyl, E = O, NBut or N–aryl). The complex [Zr{N(C6H3Pri2-2,6)C(O)N(But)}(Me4taa)] is also formed by reaction of the bis(arylimide) [Zr(NHC6H3Pri-2,6)2(Me4taa)] with ButNCO. The crystal structures of [Ti{N(Tol)C(O)O}(Me4taa)] (Tol = p-tolyl) and [Zr{N(C6H3Pri2-2,6)C(O)N(But)}(Me4taa)] are described. The tert-butyl imido complexes [Ti(NBut)(Mentaa)] (n = 4 or 8) react with Ph2NNH2 to give the corresponding terminal N,N-diphenylhydrazido derivatives [Ti(NNPh2)(Mentaa)] and these yield the cycloaddition products [Ti{N(NPh2)C(O)O}(Mentaa)] or [Ti{N(NPh2)C(O)N(Tol)}(Me4taa)] with CO2 or TolNCO, respectively. The related titanium oxo complexes [Ti(O)(Mentaa)] (n = 4 or 8) react with p-tolyl isocyanate to form the N,O-carbamate products [Ti{N(Tol)C(O)O}(Mentaa)], and with ditolylcarbodiimide to form the N,N-ureate derivative [Ti{N(Ph)C(O)N(Ph)}(Mentaa)] in which complete rupture of the TiO linkage has occurred. Reaction of the N-phenyl-N-tolyl (asymmetric) ureate [Ti{N(Ph)C(O)N(Tol)}(Me4taa)] with an excess of PhNCO gave quantitative conversion to the N,N-symmetric product [Ti{N(Ph)C(O)N(Ph)}(Me4taa)] and TolNCO. Crossover NMR tube experiments suggest that this reaction occurs via an associative mechanism.

Two- and three-dimensional CuSCN co-ordination networks including new CuSCN structural motifs

Abstract: The reaction of CuSCN with linear bridging N-donor ligands afforded two- and three-dimensional networks depending on the ligand used Reaction of two equivalents of CuSCN with one equivalent of pyrazine in ethanol and aqueous ammonia afforded the three-dimensional network [Cu2(SCN)2(pyz)]∞ Replacing pyrazine with 4,4′-bipyridyl under the same conditions gave a different three-dimensional network [Cu2(SCN)2(4,4′-bipy)]∞ In contrast two-dimensional sheets of [Cu2(SCN)2(bpe)]∞ (bpe = 1,2-trans-(4-pyridyl)ethene) were isolated from the reaction of CuSCN with bpe in a 2∶1 ratio The structures of both [Cu2(SCN)2(pyz)]∞ and [Cu2(SCN)2(4,4′-bipy)]∞ are constructed from (CuSCN)∞ layers linked in a herringbone fashion by the bridging N-donor ligands to afford three-dimensional networks The complex [Cu2(SCN)2(bpe)]∞, however, shows two-dimensional sheets which are formed from (CuSCN)∞ stair-polymers bridged by bpe ligands

Sawhorse connections in a Ag(I)-nitrite coordination network: {[Ag(pyrazine)]NO2}∞

Abstract: The Ag(I) coordination networks, {[Ag(pyrazine)]NO2}∞ and {[Ag(4,4′-bipy)]NO2}∞ have been constructed in order to investigate the effect of anion upon network topology; an unusual sawhorse connection is observed in the structure of {[Ag(pyrazine)]NO2}∞ with the nitrite anion acting to ‘block’ cis coordination sites. The preparation of extended networks using inorganic coordination polymers has become an area of increasing study in recent years One of the reasons that this interest has arisen is because the synthetic procedure used to construct these materials allows a high degree of design. Ultimately this may lead to the development of materials with tuneable properties including structures with host–guest properties similar to those observed with zeolites and compounds with interesting electronic or magnetic properties. The high degree of design arises from the coupling of the well understood coordination properties of individual metal ions and highly-developed ligand syntheses with the newer areas of supramolecular chemistry and crystal engineering We have been studying the effect of individual building-blocks upon network structure. This has included the control of network topology and interpenetration in adamantoid networks via ligand desig and studies on the effect of variation of solvent of crystallisation upon network structure The nature of the counter-anion has also been shown to have a dramatic effect upon network topology and this is particularly noticeable in Ag(I) chemistry Recently we have demonstrated that replacement of AgBF4 or AgPF6 with AgNO3 results in a fundamental change of the extended structure of a coordination polymer with the ligand 3,6-di-4-pyridyl-1,2,4,5-tetrazine due to interactions between the Ag(I) centre and the NO3- anion to give a ‘helical staircase’ structure We now report the extension of these investigations to the use of AgNO2, and report an unusual example of a sawhorse connection within an extended network.{[Ag(pyz)]NO2}∞ (pyz=pyrazine) and {[Ag(4,4′-bipy)] NO2}∞ (4,4′-bipy=4,4′-bipyridyl) were prepared as colourless microcrystalline samples by adding a solution of the appropriate ligand in EtOH to a solution of AgNO2 in H2O.† In order to assess the effect of the nitrite counter-anion upon network topology single crystals of both complexes were grown by slow diffusion between an aqueous solution of AgNO2 and an ethanolic solution of the ligand. {[Ag(pyz)]NO2}∞‡ exists as a three-dimensional network in which each Ag(I) ion adopts a distorted octahedral environment (Fig. 1): each Ag(I) centre is coordinated by two pyrazine ligands, Ag–N 2.277(5) A, which bridge adjacent Ag(I) ions, and by the chelating nitrite counter-anion, Ag–O 2.487(6) A, in the equatorial sites. The two remaining axial coordination sites are occupied by weak Ag···Ag interactions (Fig. 1). The Ag···Ag separation of 3.2168(3) Ais a typical value for Ag···Ag interactions unsupported by ligands Ag···Ag interactions have been found to be significant in the extended structures of inorganic supramolecular networks. This is perhaps best illustrated by the formation of short interactions [Ag···Ag 2.970(2) AL in the extended three-dimensional network formed by {[Ag(4,4′-bipy)]NO3}∞ in which each Ag(I) centre is coordinated by one N-donor from each of two 4,4′-bipy ligands and participates in one Ag···Ag interaction to give a T-shaped motifIt can be seen that in {[Ag(pyz)]NO2}∞ each Ag(I) ion acts as a sawhorse junction in the network, with the nitrite blocking two cis sites of the junction (Fig. 2). To our knowledge this represents the first example of such a junction within a coordination polymer array. Sawhorse junctions are extremely rare in inorganic framework structures with the most notable examples being IrF4, RhF4 and PtF4 Therefore the overall network topology (Fig. 2) can be thought of as being related to the solid-state structure of IrF4 which has been described as ‘{IrF6} octahedra which share 4 F atoms, each with one other {IrF6} group leaving a pair of cis vertices unshared’ Similarly the network of {[Ag(pyz)]NO2}∞ is built from octahedra with cis vertices unshared.The structure of {[Ag(pyz)]NO2}∞ contrasts with that observed in the corresponding NO3- salt, {[Ag(pyz)]NO3}∞ Extended chains of alternating Ag(I) ions and pyrazine ligands are observed in {[Ag(pyz)]NO3}∞12 and significantly the nitrate anion is non-coordinating, in contrast to the behaviour of the nitrite anion observed in {[Ag(pyz)]NO2}∞.Single crystal X-ray studies of {[Ag(4,4′-bipy)]NO2}∞‡ reveal that a different network structure is adopted to that observed for {[Ag(pyz)]NO2}∞. The structure consists of slightly distorted linear chains of alternating Ag(I) ions and 4,4′-bipy ligands, N–Ag–N 171.98(10)° (Fig. 3) with the NO2- anions sitting between adjacent {[Ag(4,4′-bipy)]+}∞ chains so that each Ag(I) centre forms two weak Ag···O interactions of 2.667(2) Aand one weak Ag···N interaction of 2.978(3) A. Significantly, no Ag···Ag interactions are observed in {[Ag(4,4′-bipy)]NO2}∞, in contrast to {[Ag(pyz)]NO2}∞. The bridging 4,4′-bipy ligands in {[Ag(4,4′-bipy)]NO2}∞ adopt a very twisted arrangement, with a dihedral angle between the pyridyl rings of 41.3°. This value compares with observed values of 4.3° in [{Cu(cnge)2}2(µ-4,4′-bipy)][BF4]213 (cnge=2-cyanoguanidine), and 28.0, 30.0° observed in [Cu(4,4′-bipy)(MeCN)2]BF4 Both twisted and flat 4,4′-bipy molecules are incorporated in [Cu(µ-4,4′-bipy)- (H2O)2(FBF3)2]·4,4′-bipy, with a dihedral angle of 9.29° being observed for the coordinated 4,4′bipy ligands. In contrast the non-coordinated 4,4′-bipy ligands are constrained to be ideally planar by crystallographic symmetryThe IR spectra of the two complexes {[Ag(pyz)]NO2}∞ and {[Ag(4,4′-bipy)]NO2}∞ are consistent with the non-coordinating nitrite anion in {[Ag(4,4′-bipy)]NO2}∞ [νsym(NO2)=1243 cm-1] and the chelating mode of coordination for the anion in {[Ag(pyz)]NO2}∞ [νsym(NO2)=1269 cm-1] IR spectra of both the precipitated (microcrystalline) products and single crystals were found to be identical confirming the crystal structures to be representative of the bulk.Of the few previously reported examples of structurally characterised AgNO2 complexes both strongly coordinate and uncoordinated/weakly interactin NO2- have been reported. In the former Ag–O bond lengths are comparable to those observed hereCurrent work is aimed at studying the wider application of the nitrite anion as a fundamental building-block of extended coordination polymers and investigating the use of anions as a controlling factor in Ag(I) supramolecular networks. Acknowledgements

S-Cylindrophanes: From Metal Tweezers to Metal Sandwiches.

Abstract: Inclusion of AgIand CuIions by the preorganized cylindrophane cage compound 1 provides the first examples of bis(η6) sandwich complexes of these metals. Locked in a trigonal-planar heteroatom ligand field, the guest ions are shown by NMR spectroscopy to withdraw electron density from the aromatic rings. A statistical study of η6 coordination in the solid state supports the description of arene–metal contacts between 2.5 and 3.5 A as bonds.

From molecular ribbons to a molecular fabric

Abstract: Ion-pair reinforced, hydrogen-bonded molecular ribbons are knitted together through ammonium carboxylate salt bridges into undulating sheets wherein each component participates in three ion-pairing interactions and up to twelve hydrogen bonds.

Mixed aza–thia crowns containing the 1,10-phenanthroline sub-unit. Substitution reactions in [NiL(MeCN)][BF4]2 {L = 2,5,8-trithia[9](2,9)-1,10-phenanthrolinophane}†

Abstract: The substitution reactions of the co-ordinated acetonitrile molecule in [NiL(MeCN)][BF4]2 1 (L = 2,5,8-trithia[9](2,9)-1,10-phenanthrolinophane) with different anionic and neutral ligands L′ [Cl–, Br–, I–, CN–, SCN–, H2O, pyridine (py), aniline (an), 1,3-dimethyl-4-imidazoline-2-thione (etu) or 1,3-dimethyl-4-imidazoline-2-selone (eseu)] have been studied by using electronic spectroscopy. While the reaction with all the anionic ligands is quantitative, for the neutral ones an equilibrium takes place; the corresponding equilibrium constants have been determined in MeCN at 25 °C. The complex cations [NiL(L′)](2 – n)+ (n = 0 for neutral and 1 for anionic ligands) have also been isolated in the solid state, mainly as BF4– salts and the compounds [NiL(H2O)][ClO4]2·H2O, [NiL(Cl)]Cl·H2O, [NiL(SCN)]BF4·MeNO2, [NiL(eseu)][BF4]2 and [NiL(py)][BF4]2 have been characterized by X-ray diffraction studies. In these complexes a distorted octahedral geometry is achieved at the NiII with five sites occupied by the macrocyclic ligand L and the sixth by the appropriate ligand L′. The electrochemistry of all the prepared compounds has been studied by cyclic voltammetry. In particular the reductive cyclic voltammetry of 1 in acetonitrile shows a quasi-reversible one-electron reduction wave near 1E½ = –1.0 V vs. Fc/Fc+. Electrochemical reduction by controlled-potential electrolysis at this potential in the presence of the axial ligand PMe3 and investigation of the reduced product by ESR spectroscopy confirm the reduction process to be metal based and to correspond to the formation of the [NiIL]+ species.

The asymmetric synthesis of phosphorus- and sulfur-containing tricarbonyl(η6-arene)chromium complexes using the chiral base approach

Abstract: The use of a simple chiral lithium amide base 2 enables the asymmetric transformation of tricarbonyl[η6-(diphenylphosphinoyl)benzene]chromium(0) 12 into the corresponding ortho-silylated complex in up to 86% ee. A tin derivative was prepared similarly and was then used to prepare other derivatives via reduction to the corresponding phosphine, followed by transmetallation–electrophilic quench. In the case of tricarbonyl(η6-1,3-dihydroisobenzothiophene)chromium(0) the chiral base 2 was ineffective, and it was necessary to use a bis-lithium amide base 9 to effect asymmetric substitution in high ee (up to 95%). Decomplexation gave the corresponding chiral sulfides in highly enantiomerically enriched form. In all cases the absolute stereochemistry of the products was derived by conducting X-ray structure determinations on selected examples.

Structural and spectroscopic studies of charge-transfer adducts formed between IBr and thioether crowns

Abstract: Charge-transfer complexes [9]aneS3·2IBr ([9]aneS3 = 1,4,7-trithiacyclononane), [14]aneS4·2IBr 1 ([14]aneS4 = 1,4,8,11-tetrathiacyclotetradecane), [16]aneS4·4IBr 2 ([16]aneS4 = 1,5,9,13-tetrathiacyclohexadecane) and [18]aneS6·2IBr 3 ([18]aneS6 = 1,4,7,10,13,16-hexathiacyclooctadecane) have been synthesized and the single crystal structures of 1, 2 and 3 determined. The reactions of IBr with [12]aneS4 (1,4,7,10-tetrathiacyclododecane), [15]aneS5 (1,4,7,10,13-pentathiacyclopentadecane) and [24]aneS8 (1,4,7,10,13,16,19,22-octathiacyclotetracosane) have also been examined. All the compounds were prepared by slow evaporation of solutions containing IBr and the appropriate thioether macrocycle in CH2Cl2–n-hexane. The structure determination of 1 shows the thioether crown lying across a crystallographic inversion centre with two symmetry-related IBr molecules co-ordinated through their iodine atoms to two exo-oriented S-donors [S(1)–I(1) 2.678(1), I(1)–Br(1) 2.654(2) A, S(1)–I(1)–Br(1) 175.53(4)°]. The Br· · ·Br contacts between consecutive adduct units form polymeric chains of 1 in the crystal lattice. Compound 2 is the only adduct in the present investigation to have all S-donor atoms of the macrocyclic ligand co-ordinated to IBr molecules [S(1)–I(1) 2.618(2), I(1)–Br(1) 2.7049(11), S(5)–I(5) 2.687(2), I(5)–Br(5) 2.6445(12) A, S(1)–I(1)–Br(1) 177.65(5), S(5)–I(5)–Br(5) 177.57(5)°]. The [16]aneS4·4IBr units interact with each other through I· · ·I and Br· · ·I contacts to form ribbons of interconnected molecules of 2 which propagate along the ab face diagonals of the unit cell. Compound 3 shows two symmetry-related IBr molecules co-ordinated to the macrocyclic ligand [S(1)–I(1) 2.619(3), I(1)–Br(1) 2.695(2) A, S(1)–I(1)–Br(1) 175.00(6)°]. Adduct molecules are stacked along the b axis and held together by S· · ·S interactions between [18]aneS6 units. The structural features and the FT-Raman spectra of the reported IBr adducts are compared with those of the I2 adducts obtained from the same ligands.

S-Cylindrophane: von pinzettenähnlich strukturierten Metallkomplexen zu Sandwichkomplexen

Abstract: Der Einschlus von AgI- und CuI-Ionen durch das praorganisierte Cylindrophan 1 fuhrte zu den ersten Bis(η6)-Sandwichkomplexen dieser Metalle. NMR-spektroskopisch wurde nachgewiesen, das die durch die Heteroatome trigonal-planar koordinierten Gast-Ionen die Elektronendichte an den aromatischen Ringen verringern. Nach den Ergebnissen einer statistischen Studie der η6-Koordination in Festkorpern konnen Aren-Metall-Wechselwirkungen mit Abstanden von 2.5 bis 3.5 A tatsachlich als Bindungen angesehen werden.

The diastereoselective and enantioselective substitution reactions of an isoindoline–borane complex

Abstract: The alkylation of N-methylisoindoline–borane complex, using nBuLi in THF is diastereoselective, the substitution occurring predominantly syn to the borane group. Use of the sBuLi–sparteine reagent mixture in Et2O changes the diastereoselectivity observed and enables the reaction to be conducted enantioselectively, giving the chiral isoindoline–borane complexes in up to 89% ee. The relative and absolute configurations of the chiral products were established by X-ray structure determinations and NMR studies. The new asymmetric process is shown to be an enantioselective deprotonation reaction, and the intermediate organolithium is shown to be epimerisable.

The role of π–π stacking interactions in stabilising trigonal planar copper(I) in Cu(BF4)–2,9-dimethyl-1,10-phenanthroline–nitrile systems†

Abstract: Crystallisation from MeCN solutions containing copper(I) tetrafluoroborate, 2,9-dimethyl-1,10-phenanthroline (dmp) and either 2-cyanoguanidine (cnge) or one of its substituted derivatives, 2-cyano-N,N′-dimethylguanidine (dmcnge) and 2-cyanoimino-4,6-pyrimidine (cidmp), by Et2O vapour diffusion methods yielded [Cu(dmp)(nitrile)][BF4]· xMeCN (nitrile = cnge, x = 1 2; dmcnge, x = 0; or cidmp, x = 0). In the absence of an added nitrile [Cu(dmp)(NCMe)][BF4] 3 formed. Crystallisation from CH2Cl2 solutions containing copper(I) tetrafluoroborate, dmp and cnge by Et2O vapour diffusion methods yielded [Cu(dmp)(cnge)][BF4]·0.5Et2O 1. Structural studies of 1, 2 and 3 have established that the [Cu(dmp)(nitrile)]+ cations are three-co-ordinate trigonal planar (Y-shaped) species with bidentate dmp and monodentate nitrile ligands. The MeCN molecule in 2 is hydrogen bonded to the cnge ligand in a position adjacent to the copper(I) atom. When 1, 2 and 3 are combined with a tetrahedral copper(I) species co-ordinated by a bidentate ligand, cnge and MeCN, they represent stages in a crystallographic sequence depicting associative substitution at trigonal planar copper(I). In solution an equilibrium [Ke = 3.9(6) at 298 K] exists between [Cu(NCMe)4]+, [Cu(dmp)(nitrile)x]+ (x = 1 or 2) and [Cu(dmp)2]+ cations, indicating that the stability of the [Cu(dmp)(nitrile)]+ cations in the solid phase must be due to intermolecular packing interactions. For all three structurally characterised complexes, π–π (face-to-face) stacking interactions between co-ordinated dmp molecules generate an efficient parallel packing system thus promoting the trigonal planar copper(I) co-ordination geometry.

Synthesis and crystal structures of [Na{Ph2P(S)NP(S)Ph2}(L)] (where L=triglyme or tetraglyme); two air stable complexes containing six-membered S—P—N—P—S—Na rings

Abstract: The title complexes [Na{Ph2P(S)NP(S)Ph2}(L)] (where L=triglyme 1, or tetraglyme 2) were prepared in an aqueous/methanolic mixture by reaction of the sodium salt of Ph2P(S)NHP(S)Ph2 with the respective glyme ligand Compound 1 crystallizes in the orthorhombic space group Pbca with a = 19526(5), b = 16102(4), c = 21168(5) A, and Z = 8 The complex is monomeric with all four oxygen atoms of the glyme moiety coordinated to the Na+ cation The S atoms of the Ph2P(S)NP(S)Ph2 anion are bound in a symmetrical fashion to the sodium cation Compound 2 crystallizes in the triclinic space group P $$\bar 1$$ with a = 10747 (3), b = 11541(3), c = 14932(4) A, α = 8128(3), β = 8196(4), γ = 7441(3)° and Z = 2 This structure was also found to be monomeric, with the additional oxygen of tetraglyme giving a seven coordinate rather than six coordinate Na+ cation

Intramolecular and intermolecular geometry of thiophenes with oxygen-containing substituents.

Abstract: The intramolecular and intermolecular geometries of six thiophenes carrying oxygen-containing substituents have been determined. Crystals of 2-methoxythiophene and 3-methoxythiophene were grown in situ on a diffractometer from liquid samples. The 2-methoxy group introduces significant distortions to the thiophene nucleus and each molecule participates in four S⋯O contacts leading to an infinite bilayer. The extended structure of 3-methoxythiophene comprises zigzag chains of molecules linked by S⋯O contacts. Molecules of 2-acetyl-3-methoxythiophene are arranged in pairs about inversion centres, with ring centroids 3.835 A apart. 5-Cyano-3-hydroxythiophene adopts the hydroxythiophene tautomeric form which allows conjugation between the S atom and the nitrile group: O—H⋯N hydrogen bonding leads to chains which are cross-linked by S⋯O contacts to give infinite two-dimensional layers. 5-(Methylthio)thiophen-3(2H)-one exists exclusively as the thiophen-3(2H)-one form in the solid state, allowing maximum conjugative interaction of both the ring heteroatom and the substituent with the carbonyl group: each molecule is linked to two of its neighbours through pairwise C—H⋯O interactions, forming ribbons. Spiro­[cyclohexane-1,2′-2′,3′-dihydrothiophen]-3′-one crystallizes with four independent molecules in the asymmetric unit with only minor differences between these: the five- and six-membered rings in each molecule are approximately orthogonal and C—H⋯O hydrogen bonding generates chains. The last two structures differ from the others in that they lack a fully aromatic thiophene system.

Titanium imido complexes with 1,3,5-triazacyclohexane ligands: syntheses, solution dynamics and solid state structures

Abstract: The multi-gram scale syntheses of the first 1,3,5-triazacyclohexane imido complexes [Ti(NR)(R3′tach)Cl2] (R=But, C6H3Pr2i-2,6; R′=Me, But) are described together with the X-ray structures of [Ti(NBut)(Me3tach)Cl2] and [Ti(NBut)(Bu3ttach)Cl2]; the complexes of Me3tach exhibit dynamic NMR behaviour ia an unusual trigonal twist of the facially coordinated Me3tach ligand (Me3tach and Bu3ttach=1,3,5-trimethyl- and tri-tert-butyl-1,3,5-triazacyclohexane, respectively).

The synthesis and structure of a neutral tetranuclear zinc(II) complex [Zn4(L)4] [LH2 = N,N-bis(2-mercaptoethyl)benzylamine]

Abstract: The reaction of benzylamine with ethylene sulfide yields the monoamine–dithiol N,N-bis(2-mercaptoethyl)benzylamine, LH2. Reaction of Na2L with Zn(BF4)2 affords the neutral tetranuclear complex [Zn4L4], which shows an unusual Zn4S4 metallacyclic structure.

Templatgesteuerte Anordnung von Metallaggregaten durch Imino‐Carboxylat‐Liganden

Abstract: Template in Form von Lanthanoid-, Hauptgruppen- und Nebengruppenmetallionen ermoglichen die Bildung verschiedener mehrkerniger Kafige aus [M(L)] (M=Ni, Mn; (L)2−=CH2[CH2N=C(CH3)COO−]2). Mit Lanthan fuhrt die Templatsynthese zu einem ikosaedrisch koordinierten LaIII-Ion, das von sechs [Ni(L)]-Einheiten eingeschlossen wird. Mit Natrium hingegen entsteht ein dreifach uberdachter, prismatischer [{Ni(L)}9]-Kafig, der vier Na+-Ionen im Innern enthalt. Mit Mangan schlieslich konnte ein von sechs [Mn(L)]-Fragmenten koordiniertes MnII-Ion erhalten werden, das in eine verzerrte, trigonal-prismatische Anordnung eingebettet ist (siehe Bild).

Synthesis and crystal structure of [Au2(N-Ts[9]aneNS2)Cl2]2 {N-Ts[9]aneNS2=7-(toluenesulfonyl)-7-aza-1,4-dithiacyclononane} incorporating Au···Au and π–π interactions

Abstract: Reaction of AuCl(tht) (tht=tetrahydrothiophene) with N-Ts[9]aneNS2 {N-Ts[9]aneNS2=7-(toluenesulfonyl)-7-aza- 1,4-dithiacyclononane} affords the tetranuclear Au(I) species [Au2(N-Ts[9]aneNS2)Cl2]2 which exhibits Au···Au and π–π interactions leading to an overall infinite chain structure.