Toward a dodecanuclear molecular Re(i) box: structural and spectroscopic properties

Abstract

Two tetrapyridyl ligands of 1,2,4,5-tetraethynyl(4-pyridyl)benzene (tpeb) and tetra(4-pyridyl)-tetrathiafulvalene (TTF(py)₄) were used to react with trinuclear (Re(CO)₄)₃(C₃N₃S₃) (C₃N₃S₃ = cyanurate trianion) moieties to afford hexanuclear [(Re(CO)₃)₆(tpeb)₂(C₃N₃S₃)₂]·4CH₃CN·toluene (1) and dodecanuclear [(Re(CO)₃)₁₂(TTF(py)₄)₃(C₃N₃S₃)₄]·8CH₃CN·12DMF (2) boxes, respectively, under solvothermal conditions. Surprisingly, similar tetrapyridyl ligands with different core units (i.e., benzene and tetrathiafulvalene moieties) led to dramatically different structural motifs (i.e., hexanuclear and dodecanuclear boxes). Complex 1 forms a slightly bent trigonal-prismatic structure, containing two μ₃-tpeb ligands and two Re₃C₃N₃S₃ moieties as well as a π⋯π interaction distance of 3.86 Å. It is noted that complex 2 features a novel four-star structure, and three crossed tetrathiafulvalene moieties from three μ₄-TTF(py)₄ ligands to form a triple-decker arrangement with a π⋯π interaction distance of 3.70 Å. Moreover, 1 and 2 display luminescence properties in the solid state along with electrochemical properties for complex 2 arising from the electroactive TTF core.