Size Matters: From Two-Dimensional Au^I -Tl^I Metallopolymers to Molecular Complexes by Simple Variation of the Steric Demand

Bis(acetylido) aurates(I) and thallium(I) trifluoromethylsulfonates were used to synthesize Au^I -Tl^I metallopolymers, displaying novel and unusual structural motifs of the metal-metal backbones in the solid state: a discrete molecular cluster, 1D chains of interconnected dimers, tetramers, or dodecamers of Au-Tl units, and a 2D-plane network, consisting of alternating edge-linked (AuTl)₆ and (AuTl)₄ cycles. The formation of the different architectures was primarily controlled by the steric demand of the acetylide-substituent groups. Thus, the bulkiest 2,6-diisopropylphenyl derivative yielded a molecular cluster [Tl₂ Au₃ ]. Most compounds showed bright visible photoluminescence with quantum yields of up to 25 % at ambient temperature. The color of the emitted light significantly differs with the network structure. Furthermore, theoretical studies of singlet excitations in the molecular cluster, as well as NMR and mass-spectrometric investigations of the fragmentation of the metallopolymers in solution are described in detail.