Transition metal-mediated discrimination between diastereoisomers of a new linear P2N2 ligand, L1; X-ray structure analysis of rac-L1, [Pt(rac-L1)Cl]Cl·2H2O, and an unusual RhI dimer [Rh2(rac-L1–H)2(CO)2]·2H2O

Abstract

The new linear P₂N₂ ligand 1,3-bis{(o-aminophenyl)phenylphosphino}propane, L₁, as syntheisised by reaction of (o-amonopheynyl)diphenylphosphine, L₂, with lithium and 1,3-dichloropropane, forms racemic and meso isomer with distinctly different stereochemical requirements so that on reaction with PtCl₂Y₂(Y = dimethyl sulphoxide, DMSO, or benzonitrile) they bond in tridentate and tetradentate modes respectively to give the monocationic complex [Pt(rac-L₁)Cl]⁺, (1), and the dicationic complex [Pt(meso-L₁)]²⁺, (2); X-ray structure analysis of rac-L₁, the chloride salt of (1), and the ligand bridged dimer [Rh₂(rac-L₁–H)₂(CO)₂], (3), has shown how the stereochemical requirements of this racemic ligand lead to unusual modes of co-ordination.