Synthesis and structural characterization of one- and two-dimensional coordination polymers based on platinum-silver metallic backbones

Seven Pt-Ag coordination polymers [Pt(NH3)2(NHCO(t)Bu)2Ag(H2O)](ClO4) (1), [Pt2(dap)2(NHCO(t)Bu)4Ag2(NO3)(ClO4)] (dap = 1,2-diaminopropane, 2), [Pt2(en)2(NHCO(t)Bu)4Ag2(m-C6H4(CO2)2)].3H2O (en = ethylenediamine, 3), [Pt2(NH3)2(NHCO(t)Bu)2Ag2(p-C6H4(CO2)2)].2H2O (4), [Pt3(en)3(NHCO(t)Bu)6Ag2(p-C6H4(CO2)2)(1.5)].6H2O (5), [Pt(NH3)2(NHCO(t)Bu)4Ag(4-C5H4NCO2)2].10H2O (6), and [Pt2(en)2(NHCO(t)Bu)4Ag2(4-C5H4NCO2)](ClO4) (7) were synthesized from the corresponding [Pt(RNH2)2(NHCO(t)Bu)2] and Ag salts, respectively, and their structures were determined by X-ray crystallography. The Pt and Ag units aggregate into one-dimensional chains based on Pt-Ag backbones. Compounds 1, 2, and 6 possess an extended zigzag Pt-Ag chain motif, and the metallic chains arrange in a parallel fashion into layered structures. Compounds 3-5, and 7 form 2-D brick wall sheets due to the coordination of the bifunctional anions to the Ag+ ions of the neighboring chains. These polymers are constructed based on the Pt-Ag interactions and the coordination of amidate oxygen atoms to Ag ions. There are three kinds of short Pt-Ag bonds observed in the structures of these compounds. The Pt-Ag metallic backbone is formed by the stacking unsupported Pt-Ag bonds, the amidate doubly bridged Pt-Ag bonds, and the amidate singly bridged Pt-Ag bonds. In the chains, the Pt-Ag bond distances are quite short, and appear in the range of 2.78-2.97 A, which are comparable to known Pt-Ag dative bonds.