Systematic Studies of the Structural, Magnetic, and Spectroscopic Properties of Clusters and Extended Arrays Based on Cyanide Ligands

Texas A&M Research Foundation, College Station TX

Investigators

Abstract

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor Kim Dunbar at Texas A&M University to prepare series of cyanide clusters and 1-D arrays in order to provide insight into their influence of molecular size and shape and magnitude of ground state spin (S) values as well as the combination of specific metal spin centers on the properties of high spin molecules. This proposal encompasses two main synthetic goals: (1) new bi- and tri-metallic cyanide clusters based on mixed octahedral and five-coordinate or tetrahedral geometries, and (2) families of magnetic chains with the building units being of two types: (a) square, cube or trigonal bipyramid cyanide clusters with subsitutionally labile halide ligands or dangling cyanides and (b) octahedral metal precursors with trans-diphosphine ligands. The synthesis of clusters involves the use of bidentate, tridentate or pentadentate capping ligands to restrict the dimensionality to the molecular level in order to produce molecules that exhibit slow paramagnetic relaxation with hysteresis at low temperatures. The second goal is aimed at the design of magnetic chains with strong intra-chain coupling and Ising anisotropy. Planned experiments include synthesis, structural characterization and physical properties measurements including a.c. and d.c. susceptibility and microSQUID measurements at low temperatures, as well as Mossbauer and high-field, high frequency epr spectroscopy. In addition, the electrochemical and optical properties of new compounds will be investigated to explore mixed valency and photoinduced magnetic behavior. The phenomenon of spincrossover, will also be a focus. This research has relevance to potential applications such as magnetic storage devices, magnetically bistable devices and, in general, the control of magnetic responses at small length scales. The research will provide valuable multi-disciplinary training to students and postdocs who will be exposed to both the synthetic and physical aspects of the project. Collaborations with the national and international magnetism community provide opportunities for students to learn from experts in the field. A no-fee summer workshop geared specifically for novices in the field is proposed to be held at Texas A&M University.