Synthesis and Characterization of an Amidinate‐Stabilized cis ‐1,2‐Disilylenylethene [ cis ‐LSi{C(Ph)C(H)}SiL] and a Singlet Delocalized Biradicaloid [LSi(μ 2 ‐C 2 Ph 2 ) 2 SiL]

The synthesis and characterization of novel cis ‐1,2‐disilylenylethene [ cis ‐LSi{C(Ph)C(H)}SiL] ( 2 ; L=PhC(N t Bu) 2 ) and a singlet delocalized biradicaloid [LSi(μ 2 ‐C 2 Ph 2 ) 2 SiL] ( 3 ) are described. Compound 2 was prepared by the reaction of [{PhC(N t Bu) 2 }Si:] 2 ( 1 ) with one equivalent of PhCCH in toluene. Compound 3 was synthesized by the reaction of 1 with two equivalents of PhCCPh 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 PhCCPh 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(μ 2 ‐C 2 Ph 2 ) 2 Si” six‐membered ring.