Coordination complexes of pnictogen(V) cations

Abstract The pnictogen elements can access a wide range of oxidation states and coordination numbers, but are usually associated with molecules that behave as Lewis bases. Some pnictogen based compounds exhibit Lewis acidic behaviour and the presence of a positive charge augments their electrophilicity. Pnictogen(V)-centred cationic systems have the potential to behave as highly effective Lewis acceptor sites, but are superficially developed. The rare examples of these systems are reviewed herein, including their synthesis, characterisation, structure and bonding. The molecules discussed are categorised by the generic formulae [PnX 4 L] + , [PnX 4 L 2 ] + , [PnX 2 YL] + , [PnY 2 L 2 ] + , [PnX 3 L] 2+ , [PnX 3 L 2 ] 2+ or [PnXYL 2 ] 2+ , where X is a substituent such as halide or alkyl, Y is a divalent substituent such as O, S or NR, and L is a neutral ligand. The compounds represent pnictogen analogues of transition metal coordination complexes and identify a potentially broad new direction in coordination chemistry.