Reactions of Hydridochlorosilanes with 2,2′-Bipyridine and 1,10-Phenanthroline: Complexation versus Dismutation and Metal-Catalyst-Free 1,4-Hydrosilylation

Abstract

Stable in the solid state and isolable in high yields are adducts of H(2)SiCl(2), HSiCl(3), and RSiCl(3) (R = Me, Ph) with the N,N'-chelating ligands 1,10-phenanthroline (phen; 1c), 2,2'-bipyridine (bipy; 1b), and (to a limited extent) N,N,N',N'-tetramethylethylenediamine (tmeda; 1a). The products were comprehensively characterized via multinuclear solution and solid-state NMR spectroscopy, including analysis of the (29)Si NMR chemical shift anisotropy tensors, Raman spectroscopy, elemental analyses, and, for SiCl(4)(phen) (2c), HSiCl(3)(bipy) (3b), H(2)SiCl(2)(bipy) (4b), MeSiCl(3)(phen) (5c), and PhSiCl(3)(phen) (6c), single-crystal X-ray structure analyses. The latter revealed that the nonchlorine substituents (i.e., H, Me, and Ph) are exclusively trans-disposed to the N-donor atoms of the chelating ligands. A dismutation of the complexes HXSiCl(2)(bipy) and HXSiCl(2)(tmeda) (X = H or Cl) was observed in polar solvents at elevated temperatures. This reaction is more pronounced when phen is used instead of bipy or tmeda. For MeHSiCl(2)(phen), in addition to undergoing H-Cl redistribution accompanied by the formation of 5c, an unexpected 1,4-hydrosilylation was observed. The latter was proven NMR-spectroscopically and by a single-crystal X-ray structure analysis of the product MeSiCl(2)(4H-phen) (7), a pentacoordinated silicon compound with a trigonal-bipyramidal arrangement of the subsituents and the methyl group located in an equatorial position.

2‐Acylpyrroles as Mono‐anionic O,N‐Chelating Ligands in Silicon Coordination Chemistry

“…Even though silicon complexation under H 2 elimination proved to be an elegant method for the preparation of hypercoordinate Si complexes,9 this dehydrogenative coupling is particularly interesting because of the unsaturated ligand moieties involved, that is, the carbonyl function. As shown in previous studies, addition of SiH bonds to unsaturated ligand moieties (e.g., 1,3‐H‐transfer to imine C atoms10 and 1,5‐H‐transfer to phenanthroline11) would provide an alternative reaction pathway, which has not been observed in the current case though.…”

Precision Control of Cellular Pathways with Light

“…These adducts containing hexa‐coordinated silicon atoms tend to precipitate owing to their low solubility in many organic solvents 36. Formation of related adducts of chorosilanes has already been studied 37–40. In case of hexachlorodisiloxane, however, questions arise concerning the composition of the adduct (pyridine attached to one or two of the silicon atoms) as well as its relevance in a system containing an excess hexachlorodisiloxane but under‐stoichiometric amounts of pyridine.…”

Organosilicon and ‐germanium Hydrides in Catalyst‐Free Hydrometallation Reactions

“…In contrast, treatment of 2,2‐bipyridine (bipy) and 1,10‐phenanthroline (phen) with H 2 SiCl 2 or HSiCl 3 provided the expected complexes HXSiCl 2 (bipy) and HXSiCl 2 (phen) (X = H or Cl) . However, when 1,10‐phenanthroline was treated with MeHSiCl 2 the unexpected 1,4‐hydrosilylation product MeSiCl 2 (4 H ‐phen) ( 25 ) was isolated instead of the expected complex MeHSiCl 2 (phen) (Scheme ).…”

“…Compound 25 was characterised by NMR spectroscopy and by a single‐crystal X‐ray structure analysis. There are two alternative routes for the formation of 25 : one involving an intramolecular hydrogen shift ( A ) and another involving intermolecular hydrogen transfer from a hydridosilane MeH 2 SiCl to MeSiCl 3 (phen) ( B ; Scheme ) …”