Novel transformations of lanthanide(III) disiloxanediolates with group 13 metal trialkyls are reported. Treatment of the scandium metallacrown complex[{(Ph2SiO)(2)O}(2){Li(DME)}(2)]ScCl center dot THF (1) with AlMe3 resulted in an Li-Al exchange reaction and the formation of the heterotrimetallic inorganic ring system [{(Ph2SiO)(2)O}(2){Li(THF)(2)}AlMe2]ScCl center dot THF (2). The related yttrium metallacrown [{(Ph2SiO)(2)O}(2){Li(THF)(2)}(2)]YCl center dot THF (3) reacts with lnMe(3) under the formation of the heterobimetallic Y/In disiloxanediolate complex [{(Ph2SiO)(2)O}(2){lnMe(2)(OMe)}(2)lnMe(2)]Y (4). In the latter, two monomeric Me(2)lnOMe ligands are stabilized through coordination to yttrium.