Neutral organoantimony(III) and organobismuth(III) ligands as acceptors in transition metal complexes – Role of substituents and co-ligands

•Transition metal stibine and bismuthine complexes with simultaneous donor and acceptor properties are reviewed.•Lewis acid and Lewis base properties of halostibines and halobismuthines are reviewed.•Effects of substituent types on structural properties are reviewed.

This article reviews work up until mid-2014 on the synthesis and properties of transition metal complexes containing the heavier Group 15 Sb(III) and Bi(III) ligands, of general formula ER3 (E = Sb or Bi, R = alkyl, aryl, etc., and may include a pendant donor group such as amine or ether) and ER(3−n)Xn (E = Sb or Bi, R is an organic substituent such as alkyl, aryl, etc., X is an electronegative substituent such as halide, n = 0–3) in which these ligands function as a donor to a transition metal fragment, while simultaneously participating as an acceptor to another electronegative group such as an anionic or metal-coordinated halide, or an amine, ether, etc., leading to Sb/Bi centres bearing more than eight valence electrons (‘hypervalent’). The Lewis acid properties of the halostibines and halobismuthines, ER(3−n)Xn, are also reviewed.

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