Cluster Compounds with Oxidised, Hexanuclear [Nb 6 Cl i 12 I a 6 ] n − Anions ( n =2 or 3)
Four mixed-halide cluster salts with chloride-iodide-supported octahedral Nb6 metal atoms cores were prepared and investigated. The cluster anions have the formula [Nb6 Cli12 Ia6 ]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. (Ph4 P)+ and (PPN)+ function as counter cations. The X-ray structures reveal a mixed occupation of the outer sites for only one compound, (PPN)3 [Nb6 Cli12 Ia5.047(9) Cla0.953 ]. All four compounds are obtained in high yield. If in the chemical reactions a mixture of acetic anhydride, CH2 Cl2 , 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 (Ph4 P)2 [Nb6 Cli12 Ia6 ] ⋅ 4CH2 Cl2 with I⋅⋅⋅I halogen bonding and π-π bonding interactions between the phenyl rings of the cations in (PPN)3 [Nb6 Cli12 Ia5.047(9) Cla0.953 ]. The solubility of (Ph4 P)2 [Nb6 Cli12 Ia6 ] ⋅ 4CH2 Cl2 has been determined qualitatively in a variety of solvents, and good solubility in the aprotic solvents CH3 CN, THF and CH2 Cl2 has been found.