Synthesis and characterization of 2,4,6-tris((dimethylamino)methyl)phenoxysilicon compounds

A series of 2,4,6-tris((dimethylamino)methyl)phenoxysilicon compounds Σ4−nSi(OAr)n (Σ=Cl; n=1 (1), 2 (2); Σ=Me, n=1 (3), 2 (4); Σ=Me3Si, n=1 (5), 2 (6)), PhSiHn(OAr)3−n (n=2 (7), 1 (8)) and HnSi(OAr)4−n (n=2 (9), 1 (10)) has been synthesized by various adapted methods. The compounds were characterized spectroscopically by 29Si-, 1H-, 13C-, 15N-NMR. In solution the extent of Si⋯N bond formation and coordination in these compounds is determined from the 29Si-NMR (and 15N) chemical shifts and 1JSiH. The silicon center is tetracoordinated in 3–6, pentacoordinated in 1, 2, 7, 8 and hexacoordinated [4+2] in 9. The 1H-NMR features are consistent, in all cases, with dynamic coordination mode of the o-NMe2 groups in solution at room temperature. The solid-state structures of the lithium phenolate and of compounds 6 and 9 have been determined by X-ray diffraction. The trimeric structure of ArOLi contains an Li3O3-ring that is almost perfectly planar; the structures of 6 and 9 confirm no N→Si contact in 6 and a bicapped tetrahedral silicon in 9.