Weak Magnetic COupling of Coupling of Coordinated Verdazyl Radicals through Diamagnetic Metal Ions. Synthesis, Structure, and Magnetism of a Homoleptic Copper(I) Complex

摘要

The properties of transition-metla complexes containing coordinated radicals have received a great deal of attention~(1-3). One of the main themes in contemporary metal-radical research is the design, synthesis, and study of molecular-based magnetic materials based on metal-radical assemblies. Much work has been devoted to the study of discrete and polymeric complexes of nitroxide-type radicals 1-3~(4-6) and the radical-anion-based ligands such as the semiquinones~(7-10) and radical anions of tetracyanoethylene (TCNE)~(11-13) and 7,7,8,8-tetracyanoquino-dimethane (TCNQ)~14 have also been explored. In recent years, the coordination chemistry of other radicals has been pursued, particularly complexes containing the coordinated verdazyl radicals (4). Specifically, verdazyls possessing a chelating environment (e.g., 5) are capable of coordinating to metal ions~(15-17) and metal-radical magnetic-exchange interactions can be very strong in some cases~(18,19). However, the nature of radical-radical exchange in verdazyl compexes containing at least two radicals bound to the same metal atom has not yet been addressed. To data, only one metal complex has been reported containing two bound verdazyls, and in this system, reported containing two boudn verdazyls, and in this system, the radical-radical interactions could not be ascertained because of the dominance of strong metla-radicla coupling in determining the observed magnetic behavior~19. In this paper, we report the synthesis of a new verdazyl derivative (6) and its homoleptic copper(I) complex. The diamagnetic nature of the copper ion radical magnetic interactions in the complex.