Nonlinear dynamics in a complex cubic one-dimensional model for sensory psychophysics

A cubic recursion with complex variable, has different properties in the phase spases of the reals and the imaginaries. The separation of the dynamics of the parts may be interpretable in terms of sensory intensity signal transmission through higher neural networks in man.This work was supported by the Australian Research Grants Scheme, Grant No. A28515714I in 1986, held by Prof. Gregson, to whom requests for offprints should be directed.     

Julia sets for the gamma recursion in nonlinear psychophysics

Julia sets for the map za(z–ie)(1–z)(z+ie) are illustrated for some attractors of interest. This work extends previous analyses of the cubic complex polynomial and considers dynamics in regions which may be associated with the modelling of the results of overload in sensory inputs.Work supported by grant No. A7881403 (1988) from the Australian Research Council.     

Bis(4‐hydroxy­benzoato‐O)(1,4,8,11‐tetra­aza­cyclo­tetra­decane‐κ4N)nickel(II): a three‐dimensional framework built from O—H⋯O and N—H⋯O hydrogen bonds

The title compound, [Ni(C₇H₅O₃)₂(C₁₀H₂₄N₄)], contains octahedral Ni^II in a centrosymmetric trans configuration with Ni—N distances of 2.0637 (17) and 2.0699 (16) Å and an Ni—O distance of 2.1100 (14) Å. The mol­ecules are linked by a single type of O—H?O hydrogen bond [O?O 2.618 (2) Å and O—H?O 161°] into two‐dimensional sheets; a singletype of N—H?O hydrogen bond [N?O 2.991 (2) Å and N—H?O 139°] links these sheets into a three‐dimensional framework.     

Redox control within single-site polymerization catalysts

The activity of a single-site titanium-based lactide polymerization initiator supported by a ferrocenyl-derivatized salen ligand is shown to be modulated by a chemical redox switch; a substantially higher rate of propagation is found for the neutral catalyst compared to its oxidized dicationic ferrocenium counterpart.     

Synthesis of vinylic iodides for incorporation into the C17-C27 fragment of bryostatins

Vinylic iodides were identified as useful intermediates for the synthesis of the C17-C27 fragment of the bryostatins with control of the geometry of the exocyclic methoxycarbonylmethylene group. Following literature precedent, the Piers (E)-stereoselective addition of tributyltin hydride to an alkynoate followed by ester reduction and tin-iodine exchange gave vinylic iodides that could be used to form the C20-C21 bond of the bryostatins. Chelation controlled addition of lithiated 3-silyloxypropynes to 2-alkoxyaldehydes followed by reductive iodination was used to prepare vinylic iodides that could be used in the complementary assembly of the C21-C22 bond of the bryostatins. Initial studies of the synthesis of intermediates for metathesis studies using metal catalysed reactions of a vinylic iodide for C21-C22 bond formation were complicated by cyclisation reactions.     

The synthesis, coordination chemistry and ethylene polymerisation activity of ferrocenediyl nitrogen-substituted ligands and their metal complexes

Treatment of aminoferrocene with substituted 2-hydroxybenzaldehydes yields the air- and moisture-stable ligands 1–4, which were then reacted to form the chromium dichloride complexes 5–7 and the nickel bis-chelate species 8 and 9. The metal compounds are very air-sensitive but the chromium compounds act as pre-catalysts for the polymerisation of ethylene. Reaction of 1,1′-bis(amino)ferrocene with similarly substituted 2-hydroxybenzaldehyes or simple benzaldehyde gives the ligands 10–12 and 17, respectively. The X-ray crystal structure of 11 shows the molecule to have non-crystallographic C₂ symmetry and to be linked by C–Hπ interactions between the anthracene rings. Titanium-containing complexes 13–16 can be formed utilising ligands 10–12 and there is a change in geometry within the complexes dependent on the adjacent co-ligands, whilst ligand 17 can be reacted with PdClMe(COD) to form the chelate complex 18. Cyclic voltammetric studies have been carried out on 18 and its oxidised analogue 19, but both complexes are inactive towards ethylene polymerisation.