Conversion of a Zinc Disilazide to a Zinc Hydride Mediated by LiCl
摘要:
An unusual beta-elimination reaction involving zinc(II) and LiCl is reported. LiCl and a coordinatively saturated disilazido zinc compound form an adduct that contains activated SiH moieties. In THF/toluene mixtures, this adduct is transformed into a zinc hydride and 0.5 equiv. cyclodisilazane. The Li+ and Cl- ions apparently affect the reaction pathway of the disilazido zinc in a synergistic fashion. Thus, the zinc hydride and cyclodisilazane products of formal beta-elimination are not observed upon treatment of the zinc disilazide with Cl- or Li+ separately.
Divergent reaction pathways of tris(oxazolinyl)borato zinc and magnesium silyl compounds
作者:Debabrata Mukherjee、Nicole L. Lampland、KaKing Yan、James F. Dunne、Arkady Ellern、Aaron D. Sadow
DOI:10.1039/c2cc36953b
日期:——
Synthesis and reactivity of monomeric magnesium and zinc silyl compounds To(M)M-Si(SiHMe2)3 and To(M)M-Si(SiMe3)3 are described (To(M) = tris(4,4-dimethyl-2-oxazolinyl)phenylborate). The magnesium compounds react slowly with water and air, while the zinc compounds are inert. With CO2, To(M)Mg-Si(SiHMe2)3 provides To(M)MgO2CSi(SiHMe2)3 through CO2 insertion, whereas To(M)Zn-Si(SiHMe2)3 affords To(M)ZnOCHO
Remarkably Robust Monomeric Alkylperoxyzinc Compounds from Tris(oxazolinyl)boratozinc Alkyls and O<sub>2</sub>
作者:Debabrata Mukherjee、Arkady Ellern、Aaron D. Sadow
DOI:10.1021/ja303440n
日期:2012.8.8
Metal alkylperoxides are remarkable, highly effective, yet often thermally unstable, oxidants that may react through a number of possible pathways including O-O homolytic cleavage, M-O homolytic cleavage, nucleophilic O-atom transfer, and electrophilic O-atom transfer. Here we describe a series of zinc alkyl compounds of the type To(M)ZnR (To(M) = tris(4,4-dimethyl-2-oxazolinyl)phenylborate; R = Et, n-C3H7, i-C3H7, t-Bu) that react with O-2 at 25 degrees C to form isolable monomeric alkylperoxides To(M)ZnOOR in quantitative yield. The series of zinc alkylperoxides is crystallographically characterized, and the structures show systematic variations in the Zn-O-O angle and O-O distances. The observed rate law for the reaction of To(M)ZnEt (2) and O-2 is consistent with a radical chain mechanism, where the rate-limiting S(H)2 step involves the interaction of (OOR)-O-center dot and To(M)ZnR. In contrast, To(M)ZnH and To(M)ZnMe are unchanged even to 120 degrees C under 100 psi of O-2 and in the presence of active radical chains (e.g., (OOEt)-O-center dot). This class of zinc alkylperoxides is unusually thermally robust, in that the compounds are unchanged after heating at 120 degrees C in solution for several days. Yet, these compounds are reactive as oxidants with phosphines. Additionally, an unusual alkylperoxy group transfer to organosilanes affords To(M)ZnH and ROOSiR3'.