Versatile Behavior of [Pt₂Ag₄(C⋮C-<i>t</i>-Bu)₈]:  Synthesis, Structures, and Properties of [{Pt₂Ag₄(C⋮C-<i>t</i>-Bu)₈}{Ag(bipy)}]⁴⁺ and an Unprecedented Chain Polymeric Cocrystallization Adduct with a 2,2‘-bipy Ligand

Abstract

An unusual adduct, [{Pt 2 Ag 4 (C⋮C- t -Bu) 8 ·(bipy)}] ∞ ( 3 ), has been obtained from the reaction of the hexanuclear cluster [Pt 2 Ag 4 (C⋮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 (λ max 513 nm) relative to [Pt 2 Ag 4 (C⋮C- t -Bu) 8 ] ( 1 ) (λ max 476 nm) is observed. In an attempt to obtain an analogous polymeric chain based on higher nuclearity building blocks, the reaction between [{Pt 2 Ag 8 (C⋮C- t -Bu) 8 }(OClO 3 ) 2 (OCMe 2 ) 2 ](O 2 ClO 2 ) 2 } ∞ ( 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 [{Pt 2 Ag 4 (C⋮C- t -Bu) 8 }{Ag(bipy)} 4 ](ClO 4 ) 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 [Pt 2 Ag 8 (C⋮C- t -Bu) 8 (bipy) 6 ](ClO 4 ) 4 ( 5 ).