Dinuclear Silicon Complexes of Uracil, Barbituric Acid, and 5,5-Dimethylbarbituric Acid: Hydrolytic Formation of Cyclic Oligomers

The synthesis and properties of dinuclear silicon complexes derived from uracil, barbituric acid, and 5,5-dimethylbarbituric acid, through the reaction with (chloromethyl)dimethylchlorosilane and (chloromethyl)dichloro(methyl)silane are described. The oxygen atoms are weakly coordinated to silicon in all three groups of compounds. Mild hydrolysis of the dinuclear compounds leads to formation of cyclic oligomers, with 2−9 monomer units in each, in which the individual units are connected through siloxane groups. Lithium chloride is shown to act as an effective template, restricting oligomerization to dimers and preventing higher-mass product formation.