Toward Factors Affecting the Degree of Zinc Alkyls Oxygenation: A Case of Organozinc Guanidinate Complexes

While extensive research has been carried out on the oxygenation of alkylzinc complexes for decades, this issue still remains unresolved and significant uncertainties concerning the mechanism of these reactions and the composition of the resulting products persist. These reactions are believed to proceed via the initial formation of ROOZn­(L) species, but studies on the oxygenation reactions have been substantially impeded by the low stability of the alkylperoxides. This report describes the oxygenation of a <i>tert</i>-butylzinc guanidinate, i.e. a <i>t</i>BuZn­(L)-type complex (L = deprotonated 1,4,6-triazabicyclo[3.3.0]­oct-4-ene), and the isolation and characterization of an unprecedented aggregate based on a combination of a ROOZn­(L) moiety and two parent <i>t</i>BuZn­(L) molecules, {[<i>t</i>BuZn­(L)]<sub>2</sub>[<i>t</i>BuOOZn­(L)]}. Further study revealed that examined <i>tert</i>-butylzinc guanidinate molecules exhibit an ability to entrap other oxygenated species, which was demonstrated by an aggregate containing a <i>tert</i>-butylzinc <i>tert</i>-butylperoxide and two <i>t</i>BuZn­(L) molecules, {[<i>t</i>BuZn­(L)]<sub>2</sub>[<i>t</i>BuOZn<i>t</i>Bu]}. Thus, the reported studies indicate that entrapment of the product of an oxygenation reaction by the parrent alkylzinc species is another important factor controlling the oxygenation of organometallics.