Homo- and heteroalumoxane silicates

Acid-base reactions of LAl(OH)(mu-O)Si(OH)(OtBu)(2) (L = HC[CMeNAr](2)(-), Ar = 2,6-iPr(2)C(6)H(3)) (1) with nBuLi, AlMe3, GaMe3, and ZnMe2 led to the isolation of several homo and heterometallic systems containing either the hydroxo Al-OH-M or alumoxane Al-O-M unit stabilized by a silicate moiety. In reactions with AlMe3, the stepwise deprotonation of 1 could be observed and leads to the first example of a covalent Al2SiO3 alumoxane ring and furthermore the multimetallic compounds LAl(mu-O)(mu-AlMe2)(mu-O)Si[(mu(3)-O)(AlMe2)](mu-OtBu)(OtBu) and LAl(mu(3)-O)(AlMe3)(mu-AlMe2)(mu-O)Si[(mu(3)-O)(AlMe2)](mu-OtBu)(OtBu) are formed in the presence of two or more equivalents of AlMe3. These compounds represent molecular models for a "pure" and "real" MAO and a rare case of a "free" AlMe3 molecule coordinated to an alumoxane moiety. The molecular structures of all compounds have been determined using single crystal X-ray diffraction.