Like their transition metal analogs, hexacoordinate polypyridylsilicon(IV) compounds are attractive species for electronic and catalytic applications. They exhibit multiple stable redox states, with redox potentials anodically shifted about 1 V from their transition metal(II) analogs. Furthermore, the lack of d-electrons precludes MLCT transitions. This increases their desirability as cathodic colorants, dyes that are colorless in the oxidized state but become colored upon reduction. The extensive ligand variability of the hexacoordinate polypyridylsilicon(IV) complexes could provide endless color possibilities and potentially a spectrum of colors not available with existing electrochromic materials. For example, [Si(bpy)3](PF6)4 solutions go from colorless to red, while the bis-4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine complex turns violet upon reduction (Figure 1). Polypyridylsilicon(IV) compounds are also being developed for catalytic applications. Bis-bipyridyldihydroxysilicon(IV) hexafluorophosphate compounds are being developed and tested for dual hydrogen bond catalysis. These complexes exhibit higher turnover numbers than is often seen for DHB catalysts. Also, the C2 symmetry provides the opportunity for chiral catalysis as will be discussed.

Hexacoordinate polypyridylsilicon(IV) chemistry for electronic and catalytic applications

249th National Meeting (2015)

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