Metalloaromaticity

Metalloaromaticity is the manifestation of aromatic properties in the chela te metallacycle, and was first described by Calvin and Wilson in 1945. The subject has received sporadic interest until recently, mainly due to the va gueness of the term, 'aromaticity.' In the past decade, there has been rene wed interest in the concept due to advances in synthesis, theory and the re cognition of its importance in reaction mechanisms. The concept is useful i n that it unifies the reactivity, magnetic, spectroscopic and structural pr operties of chelates in terms of the Huckel rule. This review stems from my graduate work with Dr A.B.P. Lever, in which I began to holistically under stand the properties of alpha,alpha'-diimine complexes in the context of me talloaromaticity. Others had thought along similar lines, and it is the goa l of this review to present these perspectives. (C) 2001 Elsevier Science B .V. All rights reserved.