Substituent effects on aromatic stacking interactions.

Synthetic supramolecular zipper complexes have been used to quantify substituent effects on the free energies of aromatic stacking interactions. The conformational properties of the complexes have been characterised using NMR spectroscopy in CDCl(3), and by comparison with the solid state structures of model compounds. The structural similarity of the complexes makes it possible to apply the double mutant cycle method to evaluate the magnitudes of 24 different aromatic stacking interactions.

Formation and reactivity of Ir(III) hydroxycarbonyl complexes.

Kinetic studies show that the reaction of [TpIr(CO)2] (1, Tp = hydrotris(pyrazolyl)borate) with water to give [TpIr(CO2H)(CO)H] (2) is second order (k = 1.65 x 10(-4) dm(3) mol(-1) s(-1), 25 degrees C, MeCN) with activation parameters DeltaH++= 46+/-2 kJ mol(-1) and DeltaS++ = -162+/-5 J K(-1) mol(-1). A kinetic isotope effect of k(H2O)/k(D2O) = 1.

RuII complexes incorporating tetrathiamacrocycles: synthesis and conformational analysis.

The synthesis of a series of RuII complexes incorporating thiacrown ligands ([12]ane-S4, [14]ane-S4, [16]ane-S4), as well as 2,2'-bipyridine (bpy) or pyridine, is reported. Structural studies on these complexes have been carried out using a variety of techniques. Detailed 1H NMR spectroscopic studies on the previously reported [Ru([12]ane-S4)(bpy)]2+ (1) reveal that-contrary to earlier reports-the observed fluxional 1H NMR behavior is not due to chemical exchange involving cleavage of the bpy Ru--N bond but is, in fact, due to lone-pair inversion of coordinated macrocyclic sulfur donor atoms.

Solid-supported cross-coupling catalysts derived from homogeneous nickel and palladium coordination complexes.

Solid-supported catalysts derived from homogeneous nickel(II) and palladium(II) non-symmetrical salen-type coordination complexes have been prepared and shown to be effective in the heterogeneous catalysis of carbon-carbon cross-coupling reactions. The nickel catalyst has been used in room-temperature Tamao-Kumada-Corriu reactions and the palladium catalyst in the Heck reaction at elevated temperatures. The complexes were prepared by improved methods and characterised by spectroscopic techniques.

Experimental measurement of noncovalent interactions between halogens and aromatic rings.

Chemical double mutant cycles have been used to quantify the interactions of halogens with the faces of aromatic rings in chloroform. The halogens are forced over the face of an aromatic ring by an array of hydrogen-bonding interactions that lock the complexes in a single, well-defined conformation. These interactions can also be engineered into the crystal structures of simpler model compounds, but experiments in solution show that the halogen-aromatic interactions observed in the solid state are all unfavourable, regardless of whether the aromatic rings contain electron-withdrawing or electron-donating substituents.

Metal complexes with a new N(4)O(3) amine pendant-armed macrocyclic ligand: synthesis, characterization, crystal structures, and fluorescence studies.

The synthesis of a new oxaaza macrocyclic ligand, L, derived from O(1),O(7)-bis(2-formylphenyl)-1,4,7-trioxaheptane and tren containing an amine terminal pendant arm, and its metal complexation with alkaline earth (M = Ca(2+), Sr(2+), Ba(2+)), transition (M = Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+)), post-transition (M = Pb(2+)), and Y(3+) and lanthanide (M = La(3+), Er(3+)) metal ions are reported. Crystal structures of [H(2)L](ClO(4))(2).3H(2)O, [PbL](ClO(4))(2), and [ZnLCl](ClO(4)).

Highly diastereoselective aziridination of imines with trimethylsilyldiazomethane. Subsequent silyl substitution with electrophiles, ring opening, and metalation of C-silylaziridines--a cornucopia of highly selective transformations.

Treatment of a range of N-sulfonyl (Ts and SES) imines derived from aromatic, heteroaromatic, aliphatic, and unsaturated aldehydes with trimethylsilydiazomethane gave C-silylaziridines in good yield (32-83%) and with high diastereoselectivity in favor of the cis product (80:20-100:0). In contrast, an alpha-imino ester gave predominantly the trans-aziridine (89:11) in high yield (91%). The synthetic potential of C-silylaziridines was investigated.

Noncovalent Assembly of [2]Rotaxane Architectures.

Reversible zinc-pyridine coordination and hydrogen-bonding interactions have been used to assemble a [2]rotaxane from three components. Cooperativity in the macrocyclization process that results in the porphyrin dimer makes the system exceptionally stable. However, the kinetic lability of the zinc-porphyrin interaction means the dimer is in dynamic equilibrium with its monomer, and this has been exploited in the construction of a [2]rotaxane.