Synthesis and Characterization of a Singlet Delocalized 2,4‐Diimino‐1,3‐disilacyclobutanediyl and a Silylenylsilaimine

The synthesis and characterization of a singlet delocalized 2,4‐diimino‐1,3‐disilacyclobutanediyl, [LSi(μ‐CNAr) 2 SiL] ( 2 , L: PhC(N t Bu) 2 , Ar: 2,6‐ i Pr 2 C 6 H 3 ), and a silylenylsilaimine, [LSi(NAr)SiL] ( 3 ), are described. The reaction of three equivalents of the disilylene [LSiSiL] ( 1 ) with two equivalents of ArNCNAr in toluene at room temperature for 12 h afforded [LSi(μ‐CNAr) 2 SiL] ( 2 ) and [LSi(NAr)SiL] ( 3 ) in a ratio of 1:2. Compounds 2 and 3 have been characterized by NMR spectroscopy and X‐ray crystallography. Compound 2 was also investigated by theoretical studies. The results show that compound 2 possesses singlet biradicaloid character with an extensive electronic delocalization throughout the Si 2 C 2 four‐membered ring and exocyclic CN bonds. Compound 3 is the first example of a silylenylsilaimine, which contains a low‐valent silicon center and a silaimine substituent. A mechanism for the formation of 2 and 3 is also proposed.