Soluble Alumotitanosilicates and Their Zirconium and Hafnium Analogues

The synthesis of molecular heterometallic alumosilicates in good yields has been achieved by reaction between LA1(OH center dot thf)(mu-O)Si(OH)(OtBu)(2) (1, L = [HC{C(Me) N(Ar)}(2)]-, Ar = 2,6-iPr(2)C(6)H(3)) and group 4 amides. These reactions lead to inorganic cycles (type I) and spirocycles (type II) containing six-membered rings with unprecedented inorganic cores (O-Al-O-Si-O)(n)M (n = 1, 2; M = Ti, Zr and Hf). Noteworthy, for the heavier metals, Zr and Hf, higher steric bulk in the alkyl substituent of the amide moiety is required to obtain type I compounds. The solid-state structures for all compounds were determined and reveal a tetrahedral environment for all metal atoms, dihedral angles close to 90 degrees for spirocyclic compounds, and isomorphous structures for the Zr and Hf derivatives.