NaBaM III Q 3 (M III = Al, Ga; Q = S, Se): first quaternary chalcogenides with isolated edge-sharing (MQ 6 ) 6- dimers.

In this study, a new series of NaBaM(III)Q(3) (M-III = Al, Ga; Q = S, Se) compounds featuring the first discovered isolated edge-shared (M(2)(III)Q(6))(6-) dimers in known quaternary chalcogenides were synthesized. All compounds showed clear optical anisotropy (Delta n = 0.04-0.12) mainly derived from the contribution of isolated (M(2)(III)Q(6))(6-) dimers by the real-space atom-cutting method.