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Jack M Harrowfield

Publications and source records attributed to Jack M Harrowfield.

7 recordsLinked to original sources
PubMed2004

Polyhapto-aromatic interactions in lead(II) coordination.

In its crystalline form, the Pb(II) complex of 1,3-diphenylpropane-1,3-dionate (dibenzoylmethanide, DBM(-)) can be regarded as containing polymeric chains of centrosymmetric, dimeric Pb(2)(DBM)(4) units linked through hexahapto interactions of the Pb atoms with phenyl groups from adjacent units. Each Pb atom also appears to be involved in intraunit dihapto-aromatic interactions, thus attaining a total hapticity of thirteen. Comparison with the analogous Sn(II) compound indicates that the unusually high coordination number may reflect the capacity of Pb(II) to act as both a Lewis acid and a Lewis base.

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PubMed2004

Stereochemistry in functionalized macrocycle complexes: control of hydroxyl substituent orientation.

Use of a hydroxyl-functionalized open chain tetramine in a template reaction based on its Cu(II) complex leads, after reduction, to a new tetraaza macrocycle with both amino and hydroxyl substituents. The macrocycle is formed predominantly as its trans (anti) isomer, though the cis form is detectable and both have been structurally characterized in the form of their metal complexes. Although both the Cu(II) and the Co(III) complexes of the tetramine precursor ligand have the hydroxyl group in an axial position of a chair six-membered chelate ring, the trans macrocycle forms Co(III) complexes with this substituent in both equatorial and axial positions.

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PubMed2004

Functionalized macrocycles from functionalized tetra-amines: pendent-arm macrocycles derived from dichloropivalic acid.

Reaction between ethane-1,2-diamine and 3,3'-dichloropivalic acid results in different, isomeric tetra-amine derivatives, one a tetraamino carboxylic acid and the other a carboxamidotriamino alcohol, depending upon reaction conditions. Intended conversion of the Cu(II) complex of the former to a cyclam-like macrocycle through reaction with nitroethane and formaldehyde results in isolation of derivatives of both the former and the latter. This can be rationalized by assuming the intermediacy of an azetidinone, a species similar to that seen in simpler reactions of dichloropivalates. A single reaction thereby provides pendent-arm macrocycles where one has an electrophilic and the other a nucleophilic substituent. Parallel chemistry is not seen in the reaction between propane-1,3-diamine and 3,3'-dichloropivalate.

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PubMed2004

Factors influencing solvent adduct formation by calixarenes in the solid state.

Structural studies of seven very differently functionalised derivatives of calix[4]arene have been used to provide an analysis of the numerous factors which may influence solvent adduct formation by calixarenes. Evidence is presented that even where a solvent guest is included within the calixarene cavity, interactions solely within the cavity cannot be seen as the sole influences upon the guest position and orientation.

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PubMed2003

Alkali metal ion complexes of functionalised calixarenes--competition between pendent arm and anion bonding to sodium.

Determination of the crystal structure of the acetonitrile inclusate of the complex formed between sodium trifluoromethanesulfonate (triflate, CF3SO3-) and the narrow-rim functionalised calix[4]arene, 5,11,17,23-tetra-tert-butyl-25,27-di(phenylmethoxy)-26,28-di(2'-methoxyethoxy)calix[4]arene, has shown, somewhat unexpectedly, that the diether pendent arms do not chelate the sodium cation, although coordination of all four phenolic oxygen atoms does draw the calixarene into a nearly symmetrical cone form, consistent with conclusions drawn earlier from solution 1H NMR data. Crystals of C64H80O6.NaO3S.CF3.CH3CN obtained from acetonitrile solvent are monoclinic, C2/c, a structure determination at 'low' temperature (153 K) resolving several difficulties encountered in earlier attempts to analyse data acquired at approximately 295 K, and indicative of an interesting temperature dependence of substituent and anion orientations.

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PubMed2002

Koilands from thiophiles: mercury(II) clusters from thiacalixarenes.

Tetra- and hexa-nuclear mercury(II) complexes have been obtained from tetrathiacalix[4]arene and tetramercaptotetrathiacalix[4]arene, respectively, and structurally characterised in the solid state; the complexes provide new digonal and trigonal receptors of the koiland type.

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