Aluminum–Boron Bond Formation by Boron Ester Oxidative Addition at an Alumanyl Anion

[Image: see text] The potassium diamidoalumanyl, [K{Al(SiN(Dipp))}](2) (SiN(Dipp) = {CH(2)SiMe(2)NDipp}(2)), reacts with the terminal B–O bonds of pinacolato boron esters, ROBpin (R = Me, i-Pr), and B(OMe)(3) to provide potsassium (alkoxy)borylaluminate derivatives, [K{Al(SiN(Dipp))(OR)(Bpin)}](n) (R = Me, n = 2; R = i-Pr, n = ∞) and [K{Al(SiN(Dipp))(OMe)(B(OMe)(2))}](∞), comprising Al–B σ bonds. An initial assay of the reactivity of these species with the heteroallene molecules, N,N′-diisopropylcarbodiimide and CO(2), highlights the kinetic inaccessibility of their Al–B bonds; only decomposition at high temperature is observed with the carbodiimide, whereas CO(2) preferentially inserts into the Al–O bond of [K{Al(SiN(Dipp))(OMe)(Bpin)}](2) to provide a dimeric methyl carbonate species. Treatment of the acyclic dimethoxyboryl species, however, successfully liberates a terminal alumaboronic ester featuring trigonal N(2)Al–BO(2) coordination environments at both boron and aluminum.