Chiral phosphine ligands derived from sugars.: 15. Synthesis, structure and spectroscopic studies of platinum(II) complexes with chiral phosphine substituted carbohydrate ligands

Abstract

The reactions of chiral P,O-bidentate methyl 4,6-O-benzylidene- n-deoxyl- n-(diphenylphosphino)-α- d-altropyranoside ( n-Hmbpa, n=2, 3) with [PtCl 2(NCMe) 2] gave the complexes trans-[PtCl 2( n-Hmbpa) 2] ( 1a: n=2; 1b: n=3). Treating the complexes 1a and 1b with NEt 3 or NaOMe, only the corresponding mono(alkoxo)platinum(II) complex trans-[PtCl(3-mbpa)(3-Hmbpa)] ( 2b) can be isolated and characterized. The molecular structure of 1b has been determined by X-ray analysis and shows the pyrano-ring of the ligand 3-Hmbpa in a slightly distorted chair conformation. As the oxygen donor coordinating to the Pt(II) center to form the five-membered P:O chelating alkoxoplatinum(II) complex 2b, the pyrano-ring of the ligand 3-mbpa results in a boat conformation suggested by the NMR spectra.