Charged Si Clusters in Neat Solids and the Detection of [H Si ] in Solution: A Combined NMR, Raman, Mass Spectrometric, and Quantum Chemical Investigation.

Polyanionic silicon clusters are provided by the Zintl phases K Si , comprising [Si ] units, and K Si , consisting of [Si ] and [Si ] clusters. A combination of solid-state MAS-NMR, solution NMR, and Raman spectroscopy, electrospray ionization mass spectrometry, and quantum-chemical investigations was used to investigate four- and nine-atomic silicon Zintl clusters in neat solids and solution. The results were compared to Si isotope-enriched samples. Si-MAS NMR and Raman shifts of the phase-pure solids K Si and K Si were interpreted by quantum-chemical calculations. Extraction of [Si ] clusters from K Si with liquid ammonia/222crypt and their transfer to pyridine yields in a red solid containing Si clusters. This compound was characterized by elemental and EDX analyses and Si-MAS NMR and Raman spectroscopy. Charged Si clusters were detected by Si NMR in solution. Si and H NMR spectra reveal the presence of the [H Si ] cluster anion in solution.