Versatile behavior of [Pt2Ag4(CC-t-Bu)8]:: Synthesis, structures, and properties of [{Pt2Ag4(CC-t-BU)8}{Ag(bipy)}]4+ and an unprecedented chain polymeric cocrystallization adduct with a 2,2′-bipy ligand

An unusual adduct, [{ Pt2Ag4(C drop C-t-Bu)(8).(bipy)}](infinity) (3), has been obtained from the reaction of the hexanuclear cluster [Pt2Ag4(C drop C-t-Bu)(8)] (1) with 2,2'-bipy independently of the molar ratio (1:1 or 1:excess) employed. The crystal structure of 3 shows the presence of an extended polymeric chain constructed by long-range, secondary misdirected Ag ... N interactions between the cluster units and the 2,2'-bipy ligand. 3 is highly emissive in the solid state and in frozen solution. A considerable enhancement of the luminescence and a notable red shift in the emission maximum of 3 (lambda(max) 513 nm) relative to [Pt2Ag4(C drop C-t-Bu)(8)] (1) (lambda(max) 476 nm) is observed. In an attempt to obtain an analogous polymeric chain based on higher nuclearity building blocks, the reaction between [{Pt2Ag8(C drop C-t-Bu)(8)}{(OClO3)(2)(OCMe2)(2)](O-2-ClO2)(2)}(infinity) (2) and 2,2'-bipy was also examined. Treatment of 2 with 2,2'-bipy (molar ratio 1:4, Ag:bipy 1:0.5), however, produces [{Pt2Ag4(C drop C-t-Bu)(8)}{Ag(bipy)}(4)](ClO4)(4) (4), in which the cluster unit acts as an octadentate bridging ligand toward four Ag(bipy) fragments. The use of a higher proportion of 2,2'-bipy (1:6 or 1:8 molar ratio) produces [Pt2Ag8(C drop C-t-Bu)(8)(bipy)(6)]-(ClO4)(4) (5).