Chapter 210 Half-sandwich tetrapyrrole complexes of rare earths and actinides

Abstract

Publisher Summary The tetrapyrrole derivatives such as porphyrins and phthalocyanines have aroused a widespread interest in various disciplines owing to their diverse and intriguing properties. Having a highly delocalized π system, these macrocyclic compounds exhibit a wide range of novel optical, electrical, magnetic, and spectroscopic properties. These characteristics together with their extraordinary stability render them useful in the fields of materials science, catalysis, biology, and medicine. When these macrocycles are complexed with rare-earth and actinide ions through binding with the four nitrogen atoms in the core, the unique nature of the metal ions is incorporated in the complexes, resulting in characteristic features. The first examples of this class of compounds, namely R(Pc)2 (R = Pr, Nd, Er, Lu), appeared as electrochromic materials. To date, a vast number of porphyrinato and phthalocyaninato complexes of virtually the whole series of rare earths and actinides are known. As these metal ions are normally larger than the core size of these macrocyclic ligands, the metal centers are situated out of the ring, forming either half-sandwich complexes with other uni- and/or bidentate ligands, or sandwich-type complexes in which the metal centers are sandwiched between the macrocycles.