Molecular aluminosilicate Al(SH)(micro-O)Si(OH)(O(t)Bu)(2) ( = [HC{C(Me)N(Ar)}(2)](-), Ar = 2,6-(i)Pr(2)C(6)H(3)) has been prepared from Al(SH)(2) and ((t)BuO)(2)Si(OH)(2) in high yield. When reacted with one equiv. of water, the unique aluminosilicate containing two terminal hydroxy groups Al(OH.THF)(mu-O)Si(OH)(O(t)Bu)(2) can be isolated. However, when is reacted with the bulkier silanol ((t)BuO)(3)SiOH, no reaction is observed. The desired Al(SH)(micro-O)Si(O(t)Bu)(3) can be prepared in a two-step synthesis between AlH(2) and ((t)BuO)(3)SiOH giving first Al(H)(micro-O)Si(O(t)Bu)(3), which reacts further with elemental sulfur to give as the only product. Direct hydrolysis of was conducted to obtain Al(OH)(micro-O)Si(O(t)Bu)(3), however, such hydrolysis always resulted in a complete decomposition of the starting material. Therefore we used boric acid, which condenses in non-polar solvents and slowly evolve water, to hydrolyze to under mild conditions. Compounds , and have been characterized by single-crystal X-ray diffraction.