Substitution of apical iodide ligands in octahedral molybdenum cluster complexes by N-donor molecules: Synthesis and investigation of [{Mo₆I₈} (L)I₅]- and cis-[{Mo₆I₈}(L)₂I₄] (L = CH₃CN or 1,2,4-triazole)

In this work, reactivity of the [{Mo6I8}I6]2- cluster anion toward some N-donor ligands was investigated. Heating of the solution of Cs2[{Mo6I8}I6] salt in acetonitrile leads to the partial substitution of apical iodide ligands by CH3CN molecules forming crystalline solid Cs0.1[{Mo6I8}(CH3CN)I5]0.1 & sdot;cis-[{Mo6I8}(CH3CN)2I4]0.9 & sdot;0.9CH3CN (1). The solid includes anionic [{Mo6I8}(CH3CN)I5]- and neutral cis-[{Mo6I8}(CH3CN)2I4] cluster units at a ratio of 1:9. In the crystal structure of 1, these clusters occupy common crystallographic sites, which allows us to consider this compound as a solid solution. When 1,2,4-triazole (tz) was added to the reaction mixture, a solid solution of mono- and disubstituted products was also formed and crystallized in a ratio of approximately 1:3, yielding the compound Cs0.27[{Mo6I8}(tz)I5]0.27 & sdot;cis-[{Mo6I8}(tz)2I4]0.73 (2). It was assumed that compound 2 was formed as a product of direct substitution of the apical iodide ligands by tz molecules. Structural features and luminescence properties of the new compounds 1 and 2 were studied.