Careful selection of the spacer group used to separate the metal-binding domains allows control of the directionality in a helix; self-assembly leads uniquely to a double-helical cation with a head-to-tail (HT) configuration (shown schematically) in both the solid state and solution.

No abstract

The effect of changes in the angles at the connection points of linear/circular helicates is explored as a route to control the nuclearity and architecture of metallo-supramolecular arrays. This effect is probed by changing the geometry of the metal centre used to assemble bis-pyridylimine ligands that contain a 1,3-bis(aminomethyl) benzene spacer group. Tetrahedral metal ions favour linear dimers, whereas octahedral nickel(II) predominantly gives a triangular circular helicate. Five-coordinate copper(II) falls in the middle of these extremes and results in the formation of solvent-dependent mixtures of dimer and trimer. The trinuclear, triangular, circular helicate structures, which result from coordination to copper(II) and nickel(II), are structurally characterised by X-ray crystallography and reveal that the units can aggregate into hexagonal arrays that contain anion-filled tube-like channels in the solid state.

Ein geeigneter Spacer zwischen zwei Metallbindungsstellen eines Liganden ermöglicht es, die Ausrichtung dieses Liganden in einem Helicat zu steuern; dessen Selbstorganisation führt in Lösung und im festen Zustand ausschließlich zu einem doppelhelicalen Kation mit einer Kopf‐Schwanz‐Anordnung (siehe schematische Darstellung; „H”︁ für „head”︁, „T”︁ für „tail”︁).

Pages 73-79. The reaction of cyclopropylphenylcarbinol with phosphorus tribromide at -15°g ives 4rbromo-l-phenyl-1-butene, identified by its nmr spectrum and by its conversion to trans-1phenyl-1,3-butadiene on treatment with sodium amide in liquid ammonia, rather than cyclopropylphenylcarbinyl bromide, in confirmation of the report of A. Maercker and J. D. Roberts, J.