Reactivity patterns for the activation of CO and CS with alumoxane and aluminum hydrides.

Carbon dioxide is readily fixed when reacting with either alumoxane dihydride [{MeLAl(H)}2(μ-O)] (1) or aluminum dihydride [MeLAlH2] (2) (MeL = HC[(CMe)N(2,4,6-Me3C6H2)]2-) to produce bimetallic aluminum formates [(MeLAl)2(μ-OCHO)2(μ-O)] (3) and [(MeLAl)2(μ-OCHO)2(μ-H)2] (5), respectively. Furthermore, [(MeLAl)2(μ-OCHO)2(μ-OH)2] (4) is easily obtained upon the reaction of 3 or 5 with H2O. The stability of the unusual dialuminum diformate dihydride core observed in 5 stems from the proximity of the Al centers allowing the formation of two Al-HAl bridges and precluding further hydride transfer to the HCO2 moieties.

Synthesis of Cyclic and Cage Borosilicates Based on Boronic Acids and Acetoxysilylalkoxides. Experimental and Computational Studies of the Stability Difference of Six- and Eight-Membered Rings.

A series of borosilicates was synthesized, where the structure of the borosilicate core was easily modulated using two strategies: blocking of condensation sites and controlling the stoichiometry of the reaction. Thus, on the one hand, the condensation of phenylboronic or 3-hydroxyphenylboronic acid with diacetoxysilylalkoxide [(BuO)(PhCO)Si(OAc)] led to the formation of borosilicates (BuO)(PhCO)Si{(μ-O)BPh}(μ-O) (1), [{(BuO)(PhCO)Si(μ-O)BPh(μ-O)}] (2), and [{(BuO)(PhCO)Si(μ-O)B(3-HOPh)(μ-O)}] (3) with a cyclic inorganic BSiO or BSiO core, respectively. On the other hand, the reaction of phenylboronic acid with triacetoxysilylalkoxide (PhCO)Si(OAc) in 3:2 ratio resulted in the formation of a cagelike structure [{(PhCO)Si(μ-O)BPh(μ-O)}] (4) with BSiO core, while the reaction of the boronic acid with silicon tetraacetate generated an unusual 1,3-bis(acetate)-1,3-diphenyldiboraxane PhB(μ-O)(μ-O,O'-OAc)BPh (5).