Beeinflussen interne N-Donorliganden Hydrolyse-und Kondensationsreaktionen von Chlorsilanen? / Do Internal N-Donor Ligands Influence the Hydrolysis and Condensation Reactions of Chlorosilanes?

The reaction of [C CH N(CH SiCl (1) with hydrogen chloride gives the singly protonated adduct 2. Its solid state structure has been determined by single crystal X-ray diffraction. Centrosymmetric 2 is orthorhombic, space group Pbca, a = 1694.9(2), b = 1161.7(2), c = 2501.7(3) pm; Z = 8. Controlled hydrolysis of 1 leads to the 1,3-siloxanediol 4, probably via the precursors 3a-3c which could not be isolated. The hydrogen chloride formed during the hydrolysis protonates two of the dimethylamino groups, while the other two dimethylamino functions form hydrogen bonds to the silanol groups. Centrosymmetric 4: monoclinic, space group P2 /c, a = 980.3(1), b = 933.9(1), c = 2177.5(2) pm, β = 99.94(1)°; Ζ = 4. If the hydrolysis is carried out in the presence of lithium naphthalenide, the metalated compound {[C CH N(CH Si(OLi)OH} •2 LiCl•2CHCl (5) is obtained. The solid state structure of 5 exhibits two cube-like subunits which are held together by nitrogen and oxygen lithium contacts, hydrogen bonds between silanol groups and nitrogen atoms, and which are linked by the four silicon centres. Tetrameric 5: monoclinic, space group C2/C or C ; a = 1523.6(2), b = 2440.2(1), c = 2534.8(2) pm, β = 93.83(3)°; Ζ = 8. These results show that the intramolecular donor capabilities of the dimethylaminobenzyl ligand at silicon can stabilize 1,3-siloxanediol and SiOLi substructures. Compounds like 1 serve as model compounds for the controlled formation of precursors for silicone synthesis.