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(μ2‐C2Ph2)2SiL (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(μ2‐C2Ph2)2Si” six‐membered ring. The new radicals: A novel amidinate‐stabilized singlet delocalized biradicaloid LSi(μ2‐C2Ph2)2SiL (L=PhC(NtBu)2) has been synthesized successfully by the reaction of {PhC(NtBu)2}Si2 with diphenylacetylene. X‐ray crystallography and DFT calculations show that the diradicals are stabilized by the amidinate ligand and the delocalization within the Si(μ2‐C2Ph2)2Si six‐membered ring (see figure).