Synthesis and crystal structure of [Li(NH3)(4)](4)[Sn-9]center dot NH3 and[Li(NH3)(4)](4)[Pb-9]center dot NH3

The reduction of an excess of Sn or Pb with a concentrated solution of Li i n liquid ammonia yielded black crystals of [Li(NH3)(4)](4)[Sn-9]. NH3 or [L i(NH3)(4)](4)[Pb-9]. NH3 as main product, respectively. The compounds are i sotypic and crystallise in space group P2(1)/c. They contain the isolated Z intl anions Sn-9(4-) and Pb-9(4-), which form slightly distorted monocapped square antiprisms. The lead compound is the first example of a "naked" Pb- 9(4-) cage without contacts to metal atoms.