On the structure of molybdenum diselenide and disulfide

The crystal structure of MoSe 2 has been refined from single‐crystal X‐ray diffraction data. MoSe 2 is isotypic with hexagonal MoS 2 (C7 type); a = 3.289(1) Å, c = 12.927(4) Å, z(Se) = 0.6210(3). It is pointed out that the structure of MoS 2 is incorrectly given in many books, although it had already been correctly reported by Dickinson and Pauling [4]. Corrected interatomic distances are given; the trigonal prism about Mo is almost regular.