title: Synthesis and characterization of a singlet delocalized 2,4-diimino-1,3-disilacyclobutanediyl and a silylenylsilaimine.
abstract: The synthesis and characterization of a singlet delocalized 2,4-diimino-1,3-disilacyclobutanediyl, [LSi(μ-CNAr)(2)SiL] (2, L: PhC(NtBu)(2), Ar: 2,6-iPr(2) C(6) H(3)), and a silylenylsilaimine, [LSi(=NAr)-SiL] (3), are described. The reaction of three equivalents of the disilylene [LSi-SiL] (1) with two equivalents of ArN=C=NAr 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 C=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.
authors.affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371.
authors.forename: Shu-Hua
authors.initials: SH
authors.lastname: Zhang
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Xi
authors.forename: Kok Hwa
authors.initials: KH
authors.lastname: Lim
authors.forename: Qingyong
authors.initials: Q
authors.lastname: Meng
authors.forename: Ming-Bao
authors.initials: MB
authors.lastname: Huang
authors.forename: Cheuk-Wai
authors.initials: CW
authors.lastname: So