Di[(hydroxyalkyl)dimethylammonium] tris[benzene-1,2-diolato(2–)]silicates and their germanium analogs: syntheses, crystal structure analyses, and NMR studies

Abstract

Treatment of Si(OMe)4 with three molar equivalents of 1,2-C6H4(OH)2 (= 1,2-dihydroxybenzene) and two molar equivalents of HO(CH2)nNMe2 (n = 2, 3) in acetonitrile at room temperature yields the λ6Si-silicates (HO(CH2)nNMe2H)2(SiL3) (5: n = 2; 6: n = 3; L2– = 1,2-C6H4(O)22– (= benzene-1,2-diolato(2–))). The analogous λ6Ge-germanates (HO(CH2)nNMe2H)2(GeL3) (7: n = 2; 8: n = 3) were synthesized analogously starting from Ge(OMe)4. Compounds 5·2CH3CN and 6-8 were structurally characterized by single-crystal X-ray diffraction. In addition, aqueous solutions of the Si/Ge analogs 5/7 and 6/8 were studied by NMR spectroscopy. The title compounds may be regarded as model systems for the transport and storage of silicon in biological systems and as tools to investigate biosilification.Key words: hexacoordinate silicon, hexacoordinate germanium, silicon biochemistry