Allan H. White

Bio: Allan H. White is an academic researcher from University of Western Australia. The author has contributed to research in topics: Crystal structure & Denticity. The author has an hindex of 69, co-authored 1701 publications receiving 32900 citations. Previous affiliations of Allan H. White include James Cook University & Griffith University.

Designed Synthesis of Mononuclear Tris(heteroleptic) Ruthenium Complexes Containing Bidentate Polypyridyl Ligands

Abstract: A general synthetic methodology is reported for tris(bidentate)ruthenium(II) complexes containing three different polypyridyl ligands, based on the sequential addition of the ligands to the oligomer [Ru(CO)₂Cl₂](subscript n). The tris(heteroleptic) complexes were characterized by FAB mass spectrometry and NMR spectroscopy. An X-ray crystal structure determination was made for the complex, [Ru(Me₂bpy)(phen)(bpa)](PF₆)₂. C₆H₁₄·[C₄ₒH₄₃F₁₂N₇P₂Ru, M = 1062.8; Me(2)bpy = 4,4'-dimethyl-2,2'-bipyridine, phen = 1,10-phenanthroline, bpa = bis(2-pyridyl)amine]: triclinic, space group

Cationic, linear Au(I) N-heterocyclic carbene complexes: synthesis, structure and anti-mitochondrial activity

Abstract: Six linear, two-coordinate cationic Au(I) N-heterocyclic carbene complexes of the form [(R2Im)2Au]+ (R = Me 1, Me, Et 2, i-Pr 3, n-Bu 4, t-Bu 5 and Cy 6) have been prepared by the reaction of two equivalents of the appropriate dialkylimidazol-2-ylidene (R2Im) with (Me2S)AuCl in dmf Single crystal structural studies for 1·PF6, 2·PF6, 3·Cl and 4–6·PF6 show that for all six complexes the gold(I) centres have quasi-linear C–Au–C coordination, with quasi-parallel pairs of aromatic imidazole planes, except in 5·PF6 where they are quasi-normal; in the latter, Au–C are 2038(3), 2033(3) A, cf (eg) 3 2027(2) A Inter-cation Au⋯Au are close at 3487(2), 3525(2) A in 1·PF6 and 2·PF6 The structural studies and low temperature NMR experiments provide no supportive evidence for the presence of π back-bonding within this series of complexes The lipophilicities of the six compounds, as estimated from the logarithm of the n-octanol–water partition coefficients (log P), varied across the series within the range −109 to 173 To investigate their potential as possible anti-mitochondrial anti-tumour agents, five of the compounds have been evaluated for their propensities to induce mitochondrial membrane permeabilization (MMP) in isolated rat liver mitochondria At concentrations between 1–10 µM compounds 1·Br and 3–6·Cl induced dose-dependent, Ca2+-sensitive mitochondrial swelling at rates that increased with the lipophilicities of the complexes, with the most lipophilic compounds inducing the most rapid onset of swelling The swelling was completely inhibited by cyclosporin A, the specific inhibitor of the mitochondrial permeability transition pore

Click Chemistry: Diverse Chemical Function from a Few Good Reactions.

Abstract: Examination of nature's favorite molecules reveals a striking preference for making carbon-heteroatom bonds over carbon-carbon bonds-surely no surprise given that carbon dioxide is nature's starting material and that most reactions are performed in water. Nucleic acids, proteins, and polysaccharides are condensation polymers of small subunits stitched together by carbon-heteroatom bonds. Even the 35 or so building blocks from which these crucial molecules are made each contain, at most, six contiguous C-C bonds, except for the three aromatic amino acids. Taking our cue from nature's approach, we address here the development of a set of powerful, highly reliable, and selective reactions for the rapid synthesis of useful new compounds and combinatorial libraries through heteroatom links (C-X-C), an approach we call "click chemistry". Click chemistry is at once defined, enabled, and constrained by a handful of nearly perfect "spring-loaded" reactions. The stringent criteria for a process to earn click chemistry status are described along with examples of the molecular frameworks that are easily made using this spartan, but powerful, synthetic strategy.

A critical account on π–π stacking in metal complexes with aromatic nitrogen-containing ligands

Abstract: A geometrical analysis has been performed on π–π stacking in metal complexes with aromatic nitrogen-containing ligands based on a Cambridge Structural Database search and on X-ray data of examples in the recent literature. It is evident that a face-to-face π–π alignment where most of the ring-plane area overlaps is a rare phenomenon. The usual π interaction is an offset or slipped stacking, i.e. the rings are parallel displaced. The ring normal and the vector between the ring centroids form an angle of about 20° up to centroid–centroid distances of 3.8 A. Such a parallel-displaced structure also has a contribution from π–σ attraction, the more so with increasing offset. Only a limited number of structures with a near to perfect facial alignment exists. The term π–π stacking is occasionally used even when there is no substantial overlap of the π-ring planes. There is a number of metal–ligand complexes where only the edges of the rings interact in what would be better described a C–H⋯π attraction.