SYNTHESIS, STRUCTURE, AND PHYSICOCHEMICAL PROPERTIES OF MOLECULAR RHENIUM CLUSTER COMPLEXES WITH 4-PHENYLPYRIDINE MOLECULES AS TERMINAL LIGANDS

Four novel rhenium cluster complexes with the general formula trans-[Re6Q8(ppy)4X2]·n(ppy) (Q = S, Se; X = Cl, Br; ppy = 4-phenylpyridine) are obtained by the interaction of salts Csn[Re6Q8X6]·2H2O (Q = S, n = 4; Q = Se, n = 3; X = Cl or Br) with a 4-phenylpyridine melt. The single-crystal XRD study shows that the structures of these compounds contain molecular fragments trans-[Re6Q8(ppy)4X2] packed together with 4-phenylpyridine solvate molecules and connected with these molecules by weak interactions, including hydrogen bonds and π-stacking of aromatic rings. It is shown that different halide and chalcogenide ligands of the cluster complex form different types of packing. The obtained compounds are insoluble in water and in organic solvents. The crystal samples are luminescent in the red region with emission peaks at 708-718 nm, quantum yields of 0.01-0.03, and emission lifetimes of ~ 4 μs. The electronic structure of these compounds contains ligand-centered LUMO–LUMO+3 levels localized between metal-centered HOMO and LUMO+4 levels.