Inertness of the [Re6Se5Cl3]5+ cluster core to substitution by OH− in organic solutions: synthesis, structural and liquid secondary ion mass spectroscopy characterization of K(H2O)2[Re6Se5Cl9] and (n-Bu4N)[Re6Se5Cl9] and the crystal structure of (n-Bu4N)2[Re6Se6Cl8]

Abstract

When ethanol solutions of K[Re₆Se₅Cl₉] are allowed to crystallize, the compound formulated K(H₂O)₂[Re₆Se₅Cl₉] (1) is obtained. Extensive characterization, which includes chemical analysis, X-ray structure determination and liquid secondary ion mass spectrometry (LSIMS), supports this formulation, which differs from that proposed earlier, K[Re₆Se₅(OH)₂Cl₇]·H₂O. This conclusively demonstrates that no substitution of an inner μ-core halogen by OH⁻ occurs within the cluster core. This is discussed and shown to be fully consistent with the present well-documented chemistry, which requires that substitutions of halogen by divalent elements only are allowed. The paper is complemented by the crystal structures of (n-Bu₄N)[Re₆Se₅Cl₉] and (n-Bu₄N)₂[Re₆Se₆Cl₈], which had not yet been properly reported.