Azide Chemistry – An Inorganic Perspective, Part I Metal ­Azides: Overview, General Trends and Recent Developments

With Sharpless' and Meldal's discovery of the immensely supportive effect that metal catalysis has on Huisgen's classical 1, 3‐dipolar cycloaddition, azides (RN 3 ) – long underappreciated in organic synthesis – suddenly got in the focus of attention as most crucial players in sensational ‘click chemistry'. Less noisy though with the same commitment and even a much broader scope of scientific topics and objectives, the inorganic azide chemistry has made just as great strides in the last few decades. This review (Part I) gives an introductory survey of the most important results, and informs about modern developments and general trends. Particular emphasis is placed on the recent successful approaches to highly unstable homoleptic azido metal complexes of the main group and early transition elements, as well as on the enormous structural versatility caused by the ‘flexidentate' N 3 – ligand with its unsurpassed bridging capacities. The presentation in this paper of selected compounds and reactions is meant, in a way, as a prelude to the [3+2]‐cycloadditions of metal azides and related species which will be covered in‐depths in Part II. A large part of the comments finally deals with applications in fields such as catalysis, high explosive performance or magnetism of metal compounds containing azide, today certainly one of the most attractive research areas world‐wide.