Ligand-free deltahedral clusters of silicon in solution: Synthesis, structure, and electrochemistry of Si(sub 9)(super 2-)

A study synthesizes the deltahedral nine-atom clusters of silicon, Si(sub 9)(super 2-) by mild oxidation of a liquid ammonia solution of K12Si17 with Ph3GeCl in the presence of 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) or 2,2,2,-crypt(4,7,13,16,21,24-hexaoxa-1, 10-diazabicyclo[8.8.8] hexacosane). The structural similarities and differences between Si(sub 9)(super 3-) and Si(sub 9)(super 2-) are discussed.