Cluster Compounds with Oxidised, Hexanuclear [Nb6Cli12Ia6]n− Anions (n=2 or 3)

Abstract

Abstract Four mixed‐halide cluster salts with chloride‐iodide‐supported octahedral Nb6 metal atoms cores were prepared and investigated. The cluster anions have the formula [Nb6Cli12Ia6]n− with Cl occupying the inner ligand sites and I the outer one. They are one‐ or two‐electron‐oxidized (n=2 or 3) with respect to the starting material cluster. (Ph4P)+ and (PPN)+ function as counter cations. The X‐ray structures reveal a mixed occupation of the outer sites for only one compound, (PPN)3[Nb6Cli12Ia5.047(9)Cla0.953]. All four compounds are obtained in high yield. If in the chemical reactions a mixture of acetic anhydride, CH2Cl2, and trimethylsilyl iodide is used, the resulting acidic conditions lead to form the two‐electron‐oxidised species (n=2) with 14 cluster‐based electrons (CBEs). If only acetic anhydride is used, the 15 CBE species (n=3) is obtained in high yield. Interesting intermolecular bonding is found in (Ph4P)2[Nb6Cli12Ia6] ⋅ 4CH2Cl2 with I⋅⋅⋅I halogen bonding and π‐π bonding interactions between the phenyl rings of the cations in (PPN)3[Nb6Cli12Ia5.047(9)Cla0.953]. The solubility of (Ph4P)2[Nb6Cli12Ia6] ⋅ 4CH2Cl2 has been determined qualitatively in a variety of solvents, and good solubility in the aprotic solvents CH3CN, THF and CH2Cl2 has been found.

Keywords

• cluster compounds
• halide
• niobium
• redox chemistry
• structure elucidation