The crystal structures of α-AuSe and β-AuSe

α- and β-AuSe crystallize in the space group C2 m with a = 12.202(2) and 8.355(2) A , b = 3.690(7) and 3.663(1) A , c = 8.433(2) and 6.262(1) A , β = 103.15(2) and 106.03(2) ° , respectively. Both modifications of AuSe contain Au+ and Au3+. Au+ is coordinated linearly to two Se atoms. Au3+ is surrounded by four Se atoms in the form of a planar square. These essential bonds form infinite rods parallel to the monoclinic b axis in α-AuSe and waved sheets parallel to (100) in β-AuSe. Rods and sheets are connected by weak Au-Au and Se-Se bonds in α-AuSe and by weak Au-Se bonds in β-AuSe.