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

The reactions of chiral P,O-bidentate methyl 4,6-O-benzylidene-n-deoxyl-n-( diphenylphino)-alpha-D-altropyranoside (n-Hmbpa, n = 2, 3) with [PtCl2(NCMe )(2)] gave the complexes trans-[PtCl2(n-Hmbpa)(2)] (1a: n = 2; 1b: n = 3). Treating the complexes 1a and 1b with NEt3 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 determi ned 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 confor mation suggested by the NMR spectra. (C) 1999 Elsevier Science S.A. All rig hts reserved.