Alastair J. Nielson

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The osmiophilia, under the conditions of normal tissue fixation, of the histidine, lysine, tryptophan, cysteine and methionine side chain of proteins is suggested by in vitro studies on blocked amino acids representative of such protein side chains, and the chemical nature of the reaction products elucidated. The chemical feasibility of inter- or(More)
It has been postulated that phenol-containing areas of plant and animal tissues were osmiophilic, but proof of direct interaction between osmium tetroxide and phenolic materials, or the nature of such reactions, has been lacking. We find that, under conditions similar to those of normal tissue fixation, osmium tetroxide reacts rapidly with those phenols(More)
The fully optimised DFT structure of the d(0) complex [{CH(ArO)3}Ti(NEt2)] (2) at the B3LYP level compares well with the distorted tetrahedral geometry shown by the X-ray crystal structure. QTAIM analysis of the electron density associated with the C-H···Ti interaction shows a well defined bond critical point, a bond path between the hydrogen and titanium(More)
The molecule of the title compound, [Ti2(CH3)2(CH3O)2(C11H15O)4] or {[Ti(Me)(μ-OCH3)(OC6H3CMe3-2-Me-6)]2}, has a centrosymmetric, dimeric structure with a distorted square pyramidal array about each titanium atom. The methoxide ligands form an asymmetric bridge between the two Ti(IV) atoms [Ti-O bond lengths of 1.9794 (12) and 2.0603 (12) Å] with the two(More)
Density functional theory (DFT) calculations reveal that for ligand directed aromatic ring C-H bond activation, the agostic donation can share the same antibonding acceptor orbitals as a previously unrecognised π-donation from the aromatic ring of the ligand. The recognition of carbon based orbitals assisting the agostic interaction has significant(More)
In the title solvated salt, C9H14N(+)·Cl(-)·C19H24O2·0.5C7H7, two mol-ecules of 4,4'-(propane-2,2-di-yl)bis-(2,6-di-methyl-phenol) are linked via O-H⋯Cl hydrogen bonds to two chloride ions, each of which is also engaged in N-H⋯Cl hydrogen bonding to a 4-tert-butyl-pyridinium cation, giving a cyclic hydrogen-bonded entity centred at 1/2, 1/2, 1/2. The(More)
For the d(0) complex [{Zr(CpSiMe(2)H)Cl(3)}(2)] which contains a linear Si-H···Zr interaction across the dimer, DFT calculations are in good agreement with X-ray structures. The BP86 functional shows a slightly stronger interaction than B3LYP but for qualitative purposes either functional is sufficient. QTAIM analysis shows a bond critical point (bcp) for(More)
The crystallographically centrosymmetric zwitterion bis[tris(3,5-dimethyl-2-oxidobenzyl-kappaO)ammonium]zirconium(IV) crystallizes as the chloroform disolvate, [Zr(C(27)H(31)NO(3))(2)].2CHCl(3), with the two molecules of chloroform closely associated with two of the aromatic rings. The Zr atom has a distorted octahedral geometry with three phenoxy O atoms(More)
The title complex, [Ti2Cl4{CH3C(CH2O)2(CH2OH)}2], lies across a centre of symmetry with a diethyl ether solvent mol-ecule hydrogen bonded to the -CH2OH groups on either side of it. The Ti(IV) atom is coordinated in a distorted octa-hedral geometry by a tripodal ligand and two terminal chloride atoms. There are three coordination modes for the tripodal(More)
In vitro studies on the reactions of osmium tetraoxide, OsO4, with isoquinoline, pyridine, quinuclidine, and a series of structurally related alkaloids suggest that these species, under the conditions of normal tissue staining and fixation, are potentially osmiophilic. The structure of the products and their reactions with unsaturated substrates are(More)