Syntheses and molecular structures of the tridentate phosphine ligand 2-[Ph2P(CH2)3NCH]C6H4OH (HL) and its rhenium(V) complex [ReOCl2L]·0.25CH2Cl2

Abstract

The tridentate ligand 2-[Ph₂P(CH₂)₃NCH]C₆H₄OH (HL), which contains both ‘hard’ and ‘soft’ potential donor atoms, has been synthesized. Single-crystal X-ray diffraction studies show that, in the solid state, this ligand adopts a structure in which the oxygen and nitrogen atoms are linked by an intramolecular hydrogen bond. The reaction of this material with [ReOCl₄]^– to form [ReOCl₂L] leads to the replacement of the proton in this hydrogen bond by rhenium(V), and the folding of the trimethylene chain to bring the phosphorus atom [Re–P 2.442(5)Å] into a position which allows the ligand to bind facially to the {ReO}³⁺ moiety through all three donor atoms. The co-ordination site trans to the ReO oxygen [Re–O = 1.711 (13)Å] is occupied by the phenolic oxygen [Re–O = 1.965(13)Å] and the rhenium atom has a distorted octahedral co-ordination environment.