Abstract and subjects
The structure of beta-molybdenum dichloride is compared with that of TcCl2 using EXAFS spectroscopy. For TcCl2, the Tc atom is surrounded by Tc atoms at 2.13(2), 3.45(3), 3.79(4), and 4.02(4) angstrom. For beta-MoCl2, the Mo is surroundec. by Mo atoms at 2.21(2), 2.91(3), and 3.83(4) angstrom. The latter distances are consistent with the presence of an [Mo4Cl12) unit in the solid state, one constituted by two triply Mo-Mo-bonded [Mo2Cl8] units. First-principles calculations show that beta-MoCl2 with the TcCl2 "structure type" is less stable than alpha-MoCl2 (Mo6Cl12) or [Mo4Cl12] edge-sharing clusters.