Second-sphere coordination revisited

Abstract

Since the concept of second-sphere coordination of transition metal complexes was introduced by Alfred Werner in 1913, the investigation of the phenomenon has emerged as a major thrust area - a significant part of which is based on the use of transition metal complexes as first coordination spheres as well as macrocycles as second-sphere ligands in promoting the assembly and dictating the main structural features of the secondsphere adducts. In this review, we first of all summarize the work carried out in our laboratory on the secondsphere coordination chemistry of transition metal complexes in the past three decades. Significant advances of relevance to the second-sphere coordination chemistry of square-planar gold complex anions with cyclodextrins are presented as the second part of this review. © Schweizerische Chemische Gesellschaft.