Biomedical subjects

Kathryn E Preuss

Publications and source records attributed to Kathryn E Preuss.

4 recordsLinked to original sources

PubMed2006

Dinuclear cobalt bis(dioxolene) complex exhibiting two sequential thermally induced valence tautomeric transitions.

4,6-Di-2'-pyridylpyrimidine is employed as a bis(diimine) ligand bridging two cobalt bis(dioxolene) centers. The thermally induced valence tautomeric transitions of these two metal centers are coupled through the ligand. The result is that sequential switching from high-spin Co(II) to low-spin Co(III) of one center, followed by the onset of switching of the other center at lower temperature, is observed in a solid amorphous thin film by IR absorption spectroscopy.

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PubMed2006

Testing bridge-mediated differences in dinuclear valence tautomeric behavior.

Two structurally characterized dinuclear valence tautomers are described. Cobalt ions are bridged by p- and m-phenylene units connected to 2,2'-bipyridines. X-ray crystal structures show that the molecules are in the [(Co(III))(Co(III))] forms at ca. 125 K, while spectroscopic studies show that both molecules can achieve the [(Co(II))(Co(II))] form above 400 K and confirm the [(Co(III))(Co(III))] form below 10 K. Magnetic susceptibility studies are also included. Our results highlight the necessity of studying both crystalline and amorphous samples to distinguish the effects of intrinsic electronic structure and intermolecular forces on valence tautomeric behavior.

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PubMed2005

Synthesis and magnetic properties of a 4-(2'-pyrimidyl)-1,2,3,5-dithiadiazolyl dimanganese complex.

A spin-bearing bis-bidentate ligand, designed from a pyrimidyl-substituted R-CN2S2 neutral radical, is used to co-ordinate two Mn(II) metal centres yielding a thermally stable complex with antiferromagnetic coupling between the ligand-centred spin and the metal-centred spins, and thus an overall ferrimagnetic coupling scheme with a ground state S = 9/2.

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PubMed2004

Design and synthesis of a 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl cobalt complex.

The 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl neutral radical 1 has been prepared for use as a spin-bearing bidentate ligand. The coordination of this ligand to bis(hexafluoroacetylacetonato)cobalt affords a thermally stable complex 2. Magnetic susceptibility measurements of the crystalline complex indicate ferromagnetic coupling between the ligand-centered spin and the unpaired electrons of the high-spin Co(II).

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