Tai2Cl2, eine neue Verbindung vom MX4-Typ (M=Nb, Ta; X=C1, Br, I)

Abstract

The new compound TaI2Cl2 is formed from the reaction of TaCl5 with Tal5 and Ta powder in sealed Ta containers at 450 °C. The crystal structure contains quasi one-dimensional chains of TaI4/2Cl2 octahedra, sharing opposite edges (orthorhombic, Immm, a = 831.5(5) pm, b = 993.7(4) pm, c = 748.5(4) pm; R = 0.037 for 297 independent intensities). Each chain has two Ta bridging iodine bonds alternating in length along the chain direction yielding short (314.9(2) pm) and long (433.6(3) pm) Ta-Ta distances. The electronic structure indicates a Peierls-type stabilization.