The First Platinum(IV) Complexes with Glucopyranoside Ligands. A New Coordination Mode of Carbohydrates

[(PtMe3I)4] reacts with AgBF4 in acetone to give fac-[PtMe3(Me2CO)3]BF4 (2) which was isolated as strongly
moisture and air sensitive, colorless crystals and characterized by microanalysis and NMR spectroscopy (1H, 13C,
195Pt). The X-ray structure analysis (orthorhombic, Pcab, a = 15.599(3) Å, b = 15.685(2) Å, c = 15.763(3) Å,
Z = 8) reveals that 2 is monomeric and that the cation exhibits local C3v symmetry. The reaction of 2 with
glucopyranoses (1,6-anhydro-β-d-glucopyranose (3a), 1-methyl-α-d-glucopyranoside (3b), and 1-phenyl-β-d-glucopyranoside (3c)) yields carbohydrate complexes [PtMe3L]BF4 (4a−4c, L = 3a−3c). The complexes were
characterized by microanalysis, ESI mass spectrometry and by NMR spectroscopy (1H, 13C, 195Pt) displaying that
the carbohydrates act as tridentate chelating ligands coordinated by the hydroxyl groups 2-OH and 4-OH and by
the acetal oxygen atom of the pyranose ring. This structure was also confirmed by X-ray structure analysis of 4a
(orthorhombic, P212121, a = 6.404(1) Å, b = 8.636(2) Å, c = 27.161(5) Å, Z = 4). The cyclic system of the two
five-membered and the one six-membered 1,3,2-dioxaplatina rings is not free from angle strain; two O−Pt−O
angles are distinctly smaller than 90° (O2−Pt−O5 73.6(2), O4−Pt−O5 75.6(2)°). The Pt−O bond to the acetal
oxygen atom in the pyranose ring is significantly longer (Pt−O5 2.288(5) Å) than the two Pt−OH bonds (Pt−O2
2.246(5), Pt−O4 2.248(4) and belongs to the longest Pt−O bonds at all.