Molecular ReI Cages: Structural and Luminescent Properties.

Abstract

Versatile building block [{Re(CO)4 }3 (C3 N3 S3 )] (1 a; C3 N3 S3 =cyanurate trianion) reacts with linear dipyridyl ligands [i.e., pyrazine (pz), 4,4'-bipyridine (bpy), 1,2-bis(4-pyridyl)ethylene (bpe), bis(4-pyridyl)acetylene (bpa), and 1,4-bis(pyridyl-4-ylethynyl)benzene (bpb)] and a tripyridyl ligand [1,3,5-tris(4-pyridylethynyl)benzene (tpb)] to afford a series of molecular cages [{Re(CO)3 }6 (L)3 (C3 N3 S3 )2 ] [L=pz (2), bpy (3), bpe (4), bpa (5), bpb (6)] and [{Re(CO)3 }9 (tpb)3 (C3 N3 S3 )3 ] (7) under solvothermal conditions. Various structural dimensions and motifs can be systematically tuned and obtained by using different dipyridyl and tripyridyl ligands in the reactions. The molecular cages of hexanuclear complexes 2-6 containing dipyridyl ligands feature interesting trigonal-prismatic structures with different dimensions. Furthermore, nonanuclear complex 7 has a novel triangular-star structure, and three benzene rings of tpb ligands form a triple-decker arrangement with significant π⋅⋅⋅π interactions having distances of 3.490(1) and 3.528(1) Å. In addition, molecular cages 1-3 and 5-7 exhibit luminescence in the solid state, and their luminescent properties were also studied.