article a survey is given of novel results in the field of the chemistry of a-diimine complexes of some metal atoms of the main group, transition metal and post transition metal area. It is shown that a-diimines of the type RN=C(R’)(R”)C=NR (= R-DAB) and 2C&NC(R’)=NR (= R-Pyca) are very versatile with regards to both their coordinationchemistry and chemical reactivity when coordinated to a metal or metal