How Can a Carbon Atom Be Covalently Bound to Five Ligands? The Case of Si2(CH3)7

The beauty of symmetry: The Si2(CH3)7+ ion can be observed under the low pressures used in Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry. The optimized geometry of the ion, as determined from theoretical calculations and FT‐ICR experimental results, reveals a C3h‐symmetric structure, in which a planar CH3 group is symmetrically bonded to two eclipsed Si(CH3)3 moieties (see picture; Si blue, C dark gray, H pale gray).