Reactions of the new aminosilanetriol (2,6-i-Pr2C6H3)N(SiMe2-i-Pr)Si(OH)(3) (2) with the trialkylalanes AlMe3 at 0 degrees C and (Me3Si)(3)CAlMe2.THF at room temperature in THF afford the new cubic aluminosiloxane [(2,6-i-Pr2C6H3)N(SiMe2-i-Pr)SiO3Al . THF](4) (3) and the new acyclic aluminosiloxane [(2,6-i-Pr2C6H3)N(SiMe2-i-Pr)SiO(OH)(2)](2)AlC(SiMe3)(3). 3THF (4) in good yield. These compounds have been characterized by mass, IR and multinuclear NMR spectroscopy. The X-ray structures of 2-4 are described. The molecular structure of 3 reveals an Al4Si4O12 cubic core while the molecular structure of 4 is represented by an acyclic AlSi2O2(OH)(4) unit. In 4 the silicon atoms containing the hydroxo groups are connected by an O-Al-O unit.