{Sn10 [Si(SiMe3 )3 ]4 }(2-) : A highly reactive metalloid tin cluster with an open ligand shell.

The reaction of a Sn(I) Cl solution with LiSi(SiMe3 )3 gave the anionic metalloid tin cluster {Sn10 [Si(SiMe3 )3 ]4 }(2-) (7) in good yield. The arrangement of the ten tin atoms in the cluster core can be described as a distorted centaur polyhedron. Quantum chemical calculations suggest that there are 26 bonding electrons in the cluster core, which may be described as an arachno cluster in agreement with Wade's rules. NMR and mass spectrometric investigations showed that 7 is highly reactive, which may be due to the open ligand shell. The easily available tin atoms in 7 thereby open the door to further subsequent reactions, in which 7 may act as a building block to larger cluster aggregates.