Pt2Tl Building Blocks for Two-Dimensional Extended Solids: Synthesis, Crystal Structures, and Luminescence

Abstract

The β-diketonate compounds of Pt(II), [Pt(R-C^C*)(acac)] (acacH = acetylacetone, R-CH^C* = 1-(4-cyanophenyl)-3-methyl-1H-imidazol-2-ylidene (NC–CH^C*) 1A, 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazol-2-ylidene (CO2Et-CH^C*) 1B, 1-(3,5-dichlorophenyl)-3-methyl-1H-imidazol-2-ylidene (Cl-CH^C*) 1C) containing cyclometalated N-heterocyclic carbenes were synthesized from compounds [{Pt(μ-Cl)(R-C^C*)}2] (R = CN A, CO2Et B, Cl C). Compound C was prepared for the first time following a step-by-step protocol used to synthesize A and B. The X-ray structures of complexes 1B and 1C show that only in 1B the molecules stack in pairs through intermolecular Pt···Pt (3.370 A) and π–π (∼3.43 A) interactions between the NHC ligand and the acac. The reaction of compounds 1A–1C with TlPF6 (2:1 molar ratio) leads to the clusters [{Pt(R-C^C*)(acac)}2Tl]+ (R = CN 2A, CO2Et 2B, Cl 2C), which exhibit a “Pt2Tl” sandwich structure, where two slightly distorted square planar “Pt(R-C^C*)(acac)” subunits are bonded to a Tl(I) cent...