Heteroleptic trivalent chromium in coordination chemistry: Novel building blocks for addressing old challenges in multimetallic luminescent complexes

Although less famous than low-spin trivalent cobalt found in [CoIII(NH3)6?xClx]Cl3?x (x ? 3), which was exploited by Alfred Werner during the early part of 20th century for establishing basic rules coordination chemistry, related chromium complexes exhibit comparable kinetic inertness, a rare property along 3d-transition series. The associated slow isomerisation processes are compatible with isolation well-defined heteroleptic complexes. Some subtle energetic differences between CrIII-X (X = halide, pseudo-halide, cyanide, solvent) and Cr-N bonds can be preparing stable inert cis/trans-[Cr(N ? N)2X2]+ fac/mer-[Cr(N N N)X3] primary incorporating multidentate nitrogen-containing chelate ligands. use these building blocks within frame ‘complex-as-ligand’ strategy, or via labilization remaining Cr-X pave way design discrete polymetallic assemblies photophysically appealing [CrIIIN6] chromophores could find applications as functional light-converting devices.