“…Na 2 [Hg 3 E 4 ], E = S, Se),[15f], and 3D frameworks (e.g. K 2 [Hg 2 Se 3 ], A 2 [Hg 6 E 7 ], A/E = K/S, K/Se, Rb/S, Rb/Se, Cs/S, Cs/Se),[10b], [15f], , [33a], , all of which are based on either linear, trigonal‐planar, or tetrahedral [Hg E n ] ( n = 2–4) building units.…”