Synthesis and Characterization of Platinum(II) Complexes of l -Ascorbic Acid. Crystal Structure of Ascorbato-C2,O5-ethylenediamineplatinum(II) Dihydrate

Reactions between diaminediaquaplatinum complexes [Pt(N ∩ N)(H 2 O) 2 ] 2+ and sodium ascorbate (NaHAsc) have been studied using 1 H and 195 Pt NMR spectroscopy. Mixtures of platinum ascorbate species were formed involving different binding modes of the ascorbate ligand, namely, [Pt(HAsc- O 3 )(H 2 O)(N ∩ N)] +, in which a single ascorbate acts as a monodentate ligand, the bis(ascorbate)platinum complexes [Pt(HAsc- O 3 ) 2 (N ∩ N)] and [Pt(HAsc- O 3 )(HAsc- C 2 )(N ∩ N)], and [Pt(Asc- O 2, O 3 )(N ∩ N)] and [Pt(Asc- C 2, O 5 )(N ∩ N)], in which the ascorbate acts as a chelating ligand (N ∩ N = en, N,N -dmen, N,N ‘-dmen, N,N,N ‘,N ‘-tmen; HAsc - = C 6 H 7 O 6 -, Asc 2 - = C 6 H 6 O 6 2 - ). The crystal structure of ascorbato- C 2, O 5 -ethylenediamineplatinum(II) dihydrate, [Pt(Asc- C 2, O 5 )(en)]·2H 2 O, was established by X-ray crystallography. A series of diphosphineplatinum complexes of the type [Pt(Asc- O 2, O 3 )(P ∩ P)] (P ∩ P = dppm, dppe, dppp) was prepared from the corresponding [Pt(NO 3 ) 2 (P ∩ P)] species. These have been characterized by elemental analysis and infrared and 1 H and 31 P{ 1 H} NMR spectroscopies.