| The exploration of stable organic radicals in materials has been of interest to chemists for years, research that was sparked by the discovery of a 1-dimensional conducting charge transfer salt prepared from a reaction of the acceptor molecule 7,7,8,8-tetracyanoquinodimethane (TCNQ), with the donor molecule tetrathiafulvalene (TTF). In recent years, chemists have studied the reaction of a variety of acceptors with transition metals because of their interesting magnetic as well as conducting properties. The main focus of this dissertation is the exploration of the coordination chemistry of TTF donor molecules that contain phosphorus, sulfur and carboxylate substituents. A smaller component of the thesis involves reactivity studies of the acceptor molecule 2,3,5,6-tetrapyridylpyrazine (tppz). The chelating phosphorus derivatives of TTF have been used to prepare compounds with tetrahedral Ag(I) and Cu(I) ions and square planar complexes of Pt(II) and Pd(II). X-ray structural characterization of both types of products revealed both bent and planar conformations for the TTF backbone of the phosphorus ligand. No appreciable electronic communication was observed between the TTF ligands, as judged by electrochemistry. Another derivative of TTF, 1,3-dithiole-2-one-4,5-dithiolate (dmid), exhibits excellent stability in a (diimine)Pt(dmid) complex due to the capacity of the molecule to form charge transfer salts with nitrile acceptors such as TCNQ. Another approach to TTF coordination chemistry that was used is to functionalize TTF with a carboxylate group, which opens up new avenues of chemistry as illustrated by the work in this dissertation with dirhenium compounds. Significant influences on the stability and oxidation potentials of the resulting dirhenium complexes were observed as compared to analogous compounds that contain “innocent” carboxylate ligands. Finally, the formation of mono-, di- and polynuclear complexes of the transition metals coordinated to the bis-terpyridine acceptor ligand (tppz) was achieved and the results were found to be dependent on the solvent and metal ion identity (Fe(II), Co(II), Ni(II)). The tppz complexes with cobalt atoms, which exhibit spin-crossover magnetic behavior and reversible ligand reductions, offer the most promising magnetic and electronic behavior. These results and related work will be discussed in the context of synthetic strategies, the structures, and the properties of the new compounds. |
