The Elusive Tetrasamarium‐oxide‐hexabromide, Sm₄OBr₆

Abstract

Abstract Black single crystals of tetrasamarium(II)‐oxide‐hexabromide, Sm 4 OBr 6 , were obtained from a reaction of SmBr 3 , Sm 2 O 3 and Na in a sealed tantalum container at 750 °C. Sm 4 OBr 6 crystallizes in the hexagonal space group P6 3 mc (Z = 2, a = 985.89(9), c = 753.50(6) pm, R = 0.035 for all data) as do all M 4 OX 6 type oxide halides with M = Ca,Sr,Ba,Eu,Sm,Yb and X = Cl,Br,I, as far as they have been obtained. The crystal structure is also the anti‐type of K 6 HgS 4 /Na 6 ZnO 4 with K 6 HgS 4 = Br 6 OSm 4 . The {OSm 4 } tetrahedron is surrounded by 18 bromide ligands according to {OSm2Sm1 3 }(μ 1 ‐Br1 6 )(μ 1 ‐Br2 3 )(μ 2 ‐Br1 3 )(μ 2 ‐Br2 3 )(μ 3 ‐Br2 3 ). These bromide ligands bridge to other such tetrahedra to allow for a three‐dimensional structure.