Scott W. Gordon-Wylie

Designing ligands to achieve robust oxidation catalysts. Iron based systems

Abstract Nitrile solvents containing α-CH substituents are catalytically oxidized by the tetraamido-N-FeIII-aqua complex, 3, with t-butyl hydroperoxide. Every observable product resulting from 3 has been characterized. An FeIV–cyano complex, 5, is the major inorganic product; the cyano ligand emanates from the solvent–substrate. A new type of ligand oxidative degradation giving 6 proceeds to ca. 10% of the iron macrocycle; its characterization indicates how the already robust macrocycle should be redesigned to further improve its oxidative stability. Such improvement has led to long-lived catalysts for hydrogen peroxide oxidation in water from neutral to basic pH at room temperature. Download : Download full-size image

New Magnetically Coupled Bimetallic Complexes as Potential Building Blocks for Magnetic Materials

Long-lived organic cation radical species, [1I]−and [2I]−, are formed when bimetallic CoIII or VV(O) complexes of a new binucleating ligand are oxidized by one electron. The VV(O) complex, [2I]−, has a total spin, ST, of 1/2, while the robust CoIII complex, [1I]−, has ST=3/2. The figure shows the spin arrangement within the complexes as deduced from combined EPR and SQUID measurements. The ferrimagnetic system, [1I]−, has both CoIII spin centers aligned in a common direction, an important step towards building ferromagnetic or ferrimagnetic network solids.

7,7-Dimethyl-5H-dibenzo[e,i][1,4,8]triazacycloundecine-6,9,15(7H,8H,14H)-trione pyridine solvate.

The X-ray crystal structure and hydrogen-bonding patterns of the title compound, C18H17N3O3.C5H5N, a non-N-alkylated cyclotripeptide containing one alpha- and two beta-amino acids, are reported. The amides in the 11-membered ring have an unprecedented all-transoid configuration. The torsion angles and Dunitz parameters describing non-planarity of the amides contained in the cyclotripeptide are discussed.

Ligand Design Approaches for Controlling Exchange Coupling and Fabricating Molecular Magnetic Materials

A proposal is reviewed for using ligand design to control the sign and magnitude of the exchange-coupling constant, J, in multinuclear ions. The approach promises utility for obtaining a J of ferromagnetic sign. Its origin lies in the use of a planar array of four strongly sigma-donating ligands at a first metal ion that is bridged via two of these to a second ion [1]. Strategies are discussed for extending the local concept to complete crystals. The relationships between local site and global structural parameters are summarized for chains and helices obtained by linking D3 ions. The properties of a magnetically interesting crystalline substance consisting of stacked chains are described.