The molecular alumosilicates AlL{OSi(O t Bu) 2 O}-[OSi{(μ 3 -O)(MR 2 ) 2 (μ-O t Bu)}(O t Bu)] (L = HC[CMeNAr] 2 − , where M = Al, R = Me (2), Et (3), and i Bu (4) and M = Ga, R = Me (5)) were obtained from the reaction of AlL{OSi-(O t Bu) 2 (OH)} 2 (1) with 1 or 2 equiv of the respective organometallic precursor. These compounds have a central bicyclic inorganic core formed by a six-membered AlSi 2 O 3 alumosilicate ring with a Si−O−Si unit connected via a Si−O bond to a fourmembered Al 2 O 2 alumoxane ring. These compounds are formed even though 1 is specifically designed to yield 4R alumosilicate rings that would obey the Loẅeinstein's and Dempsey's rules about concatenation between silicon and aluminum tetrahedra in alumosilicates. We propose a mechanism for this rearrangement, based on the experimental evidence and density functional theory calculations, that involves a κ 3 μ 2 coordination of a silicate unit to two AlMe 2 groups, which weakens one Si−O bond and explains how aluminum atoms can cleave Si−O bonds. Furthermore, formation of the products experimentally confirms the theory that Al−O−Al groups can exist in alumosilicates if the oxygen atom belongs to an OH moiety.