Synthesis and characterization of a singlet delocalized 2,4-diimino-1,3-disilacyclobutanediyl and a silylenylsilaimine
Xi, Hong Wei
Lim, Kok Hwa
Date of Issue2012
School of Physical and Mathematical Sciences
The synthesis and characterization of a singlet delocalized 2,4-diimino-1,3-disilacyclobutanediyl, [LSi(μ-CNAr)2SiL] (2, L: PhC(NtBu)2, Ar: 2,6-iPr2C6H3), and a silylenylsilaimine, [LSi([DOUBLE BOND]NAr)[BOND]SiL] (3), are described. The reaction of three equivalents of the disilylene [LSi[BOND]SiL] (1) with two equivalents of ArN[DOUBLE BOND]C[DOUBLE BOND]NAr in toluene at room temperature for 12 h afforded [LSi(μ-CNAr)2SiL] (2) and [LSi([DOUBLE BOND]NAr)[BOND]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 Si2C2 four-membered ring and exocyclic C[DOUBLE BOND]N 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.
Chemistry - a European journal