[Re₆Q₇O(3,5-Me₂PzH)₆]Br₂*3,5-Me₂PzH (Q = S, Se) - new octahedral rhenium cluster complexes with organic ligands: original synthetic approach and unexpected ligand exchange in cluster core

Two new octahedral rhenium cluster complexes, [Re₆S₇O(3,5-Me₂PzH)₆]Br₂*3,5-Me₂PzH and [Re₆Se₇O(3,5-Me₂PzH)₆]Br₂*3,5-Me₂PzH, with the organic ligand 3,5-dimethylpyrazole (3,5-Me₂PzH) have been synthesized by reaction of rhenium chalcobromides Cs₃[Re₆(μ₃-Q₇Br)Br₆] (Q = S, Se) with molten dimethylpyrazole. During the reaction all six apical bromine ligands of the cluster complexes are substituted by the organic ligand which is coordinated via the aromatic nitrogen N2. Additionally, the inner ligand μ₃-Br in the cluster core [Re₆(μ₃-Q₇Br)]³⁺ is substituted by oxygen given cluster cores, [Re₆(μ₃-Q₇O)]²⁺, with mixed chalcogene/oxygen ligands.