Synthesis of amidate-hanging platinum mononuclear complexes by base hydrolysis of nitrile complexes

The “amidate-hanging” Pt mononuclear complexes, which can easily bind a second metal ion with the non-coordinated oxygen atoms in the amidate moieties, have been synthesized and characterized by 1H NMR, MS, IR spectroscopy, and single crystal X-ray analysis. Five new complexes with various amidate ligands and co-ligands, cis-[Pt(PVM)2(en)] · 4H2O (1, PVM = pivaloamidate, en = ethylenediamine), cis-[Pt(PVM)2(NH2CH3)2] · H2O (2), cis-[Pt(PVM)2(NH2tBu)2] (3), cis-[Pt(TCM)2(NH3)2] (4, TCM = trichloroacetamidate), and cis-[Pt(BZM)2(NH3)2] (5, BZM = benzamidate), were successfully synthesized by direct base hydrolysis of the corresponding Pt nitrile complexes, cis-[Pt(NCR)2(Am)2]2+ (P1, P2, P3, and P5) (NCR = nitrile, Am = amine). These nitrile complexes were obtained by introducing nitriles into the Pt aqua complexes, cis-[Pt(OH2)2(Am)2](ClO4)2, whereas introduction of trichloronitrile into [Pt(OH2)2(NH3)2](ClO4)2 induced more facilitated water nucleophilic attack to afford [Pt(TCM)(NH(Cdouble bond; length as m-dashOH)CCl3)(NH3)2](ClO4) (P4). The base treatments of the precursor complexes (P1–5) lead to produce “amidate-hanging” Pt mononuclear complexes (1–5) without geometry isomerization. The 195Pt chemical shifts for 1–5 exhibit subtle differences of the Pt electron densities among them.