Recent developments in two coordinate transition metal chemistry

Abstract

Stabilization of transition metals in unusually low coordination numbers, in particular two- or quasi-two-coordinated metal centers is a challenging area of interest in coordination chemistry. The use of appropriate and sterically bulky ligands has provided the possibility to not only isolate such rare species but also to explore their bonding as well as chemical reactivity due to metal unsaturation. The fine tuning of bulk and electronic effect in ligand design plays an important role as too much steric bulk of the ligands may limit their reactivity by restricting the approach of any further ligands. Despite synthetic difficulties the isolation and characterization of such low coordinate transition metal complexes has received a great amount of attention in recent years. In this review, the synthetic approaches as well as establishment of their geometric and electronic structures by advanced spectroscopic techniques of the last decade are discussed.