Synthesis and Characterization of an Amidinate-Stabilized cis-1,2-Disilylenylethene [cis-LSi{C(Ph)=C(H)}SiL] and a Singlet Delocalized Biradicaloid [LSi(mu(2)-C2Ph2)(2)SiL]

The synthesis and characterization of novel cis-1,2-disilylenylethene [cis-LSi{C(Ph)=C(H)}SiL] (2; L=PhC-(NtBu)(2)) and a singlet delocalized biradicaloid [LSi(mu(2)-C2Ph2)(2)SiL] (3) are described. Compound 2 was prepared by the reaction of [{PhC(NtBu)(2)}Si:](2) (1) with one equivalent of PhC CH in toluene. Compound 3 was synthesized by the reaction of 1 with two equivalents of PhC CPh in toluene. The results suggest that the reaction proceeds through an [LSi{C(Ph)=C(Ph)}SiL] intermediate, which then reacts with another molecule of PhC CPh to form 3. Compounds 2 and 3 have been characterized by X-ray crystallography and NMR spectroscopy. X-ray crystallography and DFT calculations of 3 show that the singlet biradicals are stabilized by the amidinate ligand and the delocalization within the Si(mu(2)-C2Ph2)(2)Si six-membered ring.