Synthesis and structural characterization of zwitterionic oxorhenium(V) complexes with 2-hydroxypyridine

[ReOX3(PPh3)2] complexes (X = Cl and Br) react with equivalent amounts of 2-hydroxypyridine (Hhp) under formation of the mono-substituted, zwitterionic complexes mer-[ReOCl3(Hhp)(PPh3)] (1) and mer-[ReOBr3(Hhp)(PPh3)] (2). Crystal structure determinations of 1 · CH2Cl2 and 2 revealed the Cl and Br ligands adopt a mer arrangement. The Hhp ligands coordinate neutral and monodentate via their exocyclic oxygen atoms in axial positions, trans to the oxo groups. The distorted octahedral coordination sphere of the rhenium(V) complexes is completed by the phosphorus atom of the remaining PPh3 ligand.