Soluble Alumotitanosilicates and Their Zirconium and Hafnium Analogues

The synthesis of molecular heterometallic alumosilicates in good yields has been achieved by reaction between LAl(OH·thf)(μ-O)Si(OH)(OtBu)2 (1, L = [HC{C(Me)N(Ar)}2]–, Ar = 2,6-iPr2C6H3) 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)nM (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° for spirocyclic compounds, and isomorphous structures for the Zr and Hf derivatives.