Elizabeth J. MacLean

Synthetic studies related to diketopyrrolopyrrole (DPP) pigments. Part 1: The search for alkenyl-DPPs. Unsaturated nitriles in standard DPP syntheses: a novel cyclopenta[c]pyrrolone chromophore

Abstract Reactions of the anion of ethyl 4,5-dihydro-5-oxo-2-phenylpyrrole-3-carboxylate with the Diels–Alder adducts of acrylonitrile and various dienes rarely yield the expected DPP derivatives. The reaction with cyclohex-3-enecarbonitrile provides a noteworthy exception: thermolysis of the resulting cyclohexenyl-DPP gives butadiene and impure 3-ethenyl-6-phenyl-DPP, the latter being thermally unstable. Michael additions predominate when the above anion reacts with α,β-unsaturated nitriles: acrylonitrile and methacrylonitrile give 4,4-bis(cyanoethyl) and 4,4-bis(2-cyanopropyl) derivatives, and cinnamonitrile, substituted cinnamonitriles and 3-(2-thienyl)acrylonitrile give deep red 3-aryl-5-cyano-4-hydroxy-2H-cyclopenta[c]pyrrol-1-ones. These ambident nucleophiles may undergo N- and either O- or C-alkylation according to the alkylating agent used.

Strategies for the synthesis of porous metal phosphonate materials

The use of bifunctional phosphonate anions and metal cations that can adopt different co-ordination environments is proposed as a strategy for synthesising porous metal phosphonates. The hydrothermal methods described use phosphonic acids and dialkylphosphonates, which are hydrolysed in situ by the acidic metal solutions, to derive the desired phosphonate anions. A series of isostructural hydroxymethylphosphonates, M(O3PCH2OH) [M = Zn, Co, Cu and Mn], which contain a hexagonal array of cylindrical channels (approximate diameter 5.7 A), were prepared by reaction of the relevant metal acetate with diethyl hydroxymethylphosphonate. Zn(O3PCH2C(O)NH2)·H2O was prepared by reaction of zinc acetate and diethyl cyanomethylphosphonate. The structure was determined by single crystal X-ray diffraction and contains two orthogonal channel systems with water molecules situated at the intersections of the channels. Zn3(O3PCH2CO2)2·nH2O [n = 3, 4] was prepared by reaction of phosphonoacetic acid and zinc acetate. Single crystal analysis reveals the presence of channels in the [100] direction with a cross-section of 10.02 × 6.78 A. All three of the Zn-based materials can be isomorphously doped with Co.

Spin transition in a triazine-based Fe(II) complex: variable-temperature structural, thermal, magnetic and spectroscopic studies

The crystal structure of a new monomeric Fe(II) spin-crossover thiocyanate complex with a polypyridyl triazine-based ligand is reported at three temperatures. Spectroscopic, thermal and magnetic studies are presented that allowed the characterization of the thermal spin-crossover experienced by this compound and its cooperative character. The temperature of the transition is close to 200 K and the process is characterized by thermodynamic variations of ΔtrsH = 7.22(2) kJ mol−1 and ΔtrsS = 36.4(2) J mol−1 K−1.

Dirhodium(II) carboxylate complexes as building blocks. Synthesis and structures of square boxes with tilted walls

The crystal structures of four new molecular boxes with substituted benzene-1,4-dicarboxylate side walls are described, showing how substituents larger than hydroxyl cause the walls to tilt in the solid state.

The effect of substitution of a thioether donor by a phosphine donor in thiacrown complexes of iron

Abstract Electrospray mass spectrometry and thermogravimetric analysis reveals that bis(1-phenyl-1-phospha-4,7-dithiacyclononane)iron(II) is more susceptible to ethene loss than bis(1,4,7-trithiacyclononane)iron(II). This is in accord with X-ray crystallographic studies, which show that the C–S bonds are longer in the former complex suggesting an increased population of the C–S σ* π-acceptor orbitals.

2,4,6-Triisopropylbenzenesulfonamide: Monte Carlo structure solution from X-ray powder diffraction data for a molecular system containing four independent asymmetric rotors.

The crystal structure of 2,4,6-triisopropylbenzenesulfonamide, C(15)H(25)NO(2)S, has been solved from X-ray powder diffraction data collected at 120 (1) K using synchrotron radiation and refined by Rietveld methods. The structure was solved by the application of a Monte Carlo method in which trial structures were generated by random movement of the molecule in the unit cell and assessed using a full-profile-fitting technique. Intramolecular flexibility was introduced into the structure solution in the form of four independent asymmetric rotors, allowing the isopropyl and sulfonamide groups to rotate freely within the molecule. The structure is monoclinic P2(1)/c, a = 16.9600 (6), b = 8.1382 (2), c = 11.7810 (2) Å, beta = 104.777 (2) degrees with Z = 4. The molecules are linked by N-H.O hydrogen bonds, with N.O distances of 2.77 (1) and 2.92 (1) Å, into two-dimensional sheets built from R(2)(2)(8) and R(6)(6)(20) rings.

Polymorphism in nickel phosphonates: synthesis of layered and microporous Ni(O3PCH2C(O)NH2)·H2O

Two new polymorphic nickel phosphonates have been prepared by a reaction between nickel acetate and diethyl cyanomethylphosphonate. The acidity of the nickel solution affects the hydrolysis of the phosphonate to produce the phosphonic acid in situ.

Tillmannsite, (Ag3Hg)(V, As)O4, a new mineral : its description and crystal structure

Tillmannsite, (Ag 3 Hg)(V, As)O 4 , was found in the old copper mines of Roua (Alpes-Maritimes, France), associated with pecoraite, vesignieite, olivenite, kolfanite, janggunite, chlorargyrite, cuprite, native copper, native silver, native silver containing 2 % of mercury, domeykite, djurleite and algodonite. It forms aggregates (0.2 mm diameter) consisting of pseudooctahedral crystals (50 μm maximum dimension). The crystals are red, brownish red. The mineral is tetragonal, I 4, a = 7.727(7) A, c = 4.648(5) A, V = 277.5(5) A 3 , Z = 2 and D calc = 7.733(3) g/cm 3 . The strongest lines in the X-ray powder diffraction pattern (d obs in A, (hkl), I VIS ) are: 5.45, (110), 25; 2.772, (211), 100; 2.324, (002), 30; 2.254, (301), 20. Luster is adamantine translucent, streak is brownish red; crystals are uniaxial(+) with ω ∼ 2.3, ϵ ∼ 2.5 at 589 nm. Pleochroism is intense with ϵ = red orange intense, ω = orange brown. The crystal structure was solved from data collected using synchrotron radiation by traditional direct methods and refined using 350 observed unique reflections to R (F) = 0.037, Rw (F 2 ) = 0.075. The structure of tillmannsite containes isolated tetrahedra (V, As)O 4 and tetrahedral clusters (Ag 3 Hg) formed by metallic atoms. Each (Ag, Hg) metallic atom is coordinated by 3 metallic neighbors and by 3 oxygens.

Crystal Structure of Zdenekite NaPbCu5(AsO4)4Cl · 5H2O

The crystal structure of the mineral zdenekite NaPbCu5(AsO4)4Cl · 5H2O was established (Bruker SMART CCD diffractometer, synchrotron radiation, λ = 0.6843Å, R = 0.096 for 1356 reflections). Single-crystal X-ray diffraction study demonstrated that zdenekite belongs to the monoclinic system with the unit-cell parameters a = 10.023(7) Å, b = 19.55(1) Å, c = 10.023(6) Å, β = 90.02(1)°, sp. gr. P21/n, Z = 4. The structure consists of polyhedral layers parallel to the (010) plane. These layers are formed by Cuϕ polyhedra φ = O, Cl, H2O) and AsO4 tetrahedra. Distorted Na octahedra and Pb 7-vertex polyhedra and H2O molecules coordinated to these metal atoms are located between the layers.

Crystal structure of mahnertite

Mahnertite, (Na 0.88 Ca 0.12 )Cu 2.75 [AsO 4 ] 2 Cl 0.62 ·3.63 H 2 O, M = 565.17, is tetragonal, with space group I 4/ mmm, a = 10.037(1), c = 23.739(1) A, V = 2391.5(4) A 3 , Z = 8, ρ o = 3.32, ρ c = 3.14 g/cm 3 , μ = 9.78 mm -1 . The crystal structure of mahnertite was solved and refined against data collected at the Daresbury Synchrotron Radiation Source, using a 20 × 20 × 2 μm 3 single crystal, Λ = 0.6898 A, F (000) = 2150, R = 0.049 for 639 reflections with I > 2σ( I ). The structure consists of sheets parallel to (001), which comprise two symmetrically independent distorted Cu 5-vertex square pyramids Cuϕ 5 (ϕ =O, Cl or H 2 O) as well as AsO 4 tetrahedra. Four Cuϕ 5 pyramids located around the 4-fold axis share edges to form clusters linked by AsO 4 tetrahedra. The sheets are linked by the common apical vertex of the Cu(2)ϕ 5 polyhedra. As a result, a heterogeneous framework is formed. (Na,Ca) atoms, additional Cu(3) cations and H 2 O molecules are located in the interlayers. The mineral is structurally related to zdenekite, NaPbCu 5 (AsO 4 ) 4 Cl·5H 2 O.