Acetic Acid Mediated Synthesis of Phosphonate‐Substituted Titanium Oxo Clusters

New phosphonate/acetate‐substituted titanium oxo/alkoxo clusters were prepared from Ti(O i Pr) 4 and bis(trimethylsilyl) phosphonates in the presence of acetic acid, which served to generate water in situ through ester formation. The process led to clusters with a higher degree of condensation than in previously known phosphonate‐substituted titanium oxo clusters. The clusters [Ti 6 O 4 (O i Pr) 10 (OAc) 2 (O 3 PR) 2 ] (OAc = acetate) were obtained for a large variety of functional and non‐functional groups R under a range of reaction conditions. This cluster type, which is also retained in solution, therefore appears to be very robust. Two other clusters, [Ti 5 O(O i Pr) 11 (OAc)(O 3 PCH 2 CH 2 CH 2 Br) 3 ] and [Ti 5 O 3 (O i Pr) 6 (OAc) 4 (O 3 P‐xylyl) 2 ], were only isolated in special cases.