Three at a Time: Step by Step to Heterotermetallic Molecules

New structural motifs in ternary metal alkoxides are demonstrated through synthetic strategies that enable overcoming statistical barriers and solution equilibrium. Tetradentate dimetalate unit, {M₂(O<i>i</i>Pr)₉}⁻ (M = Hf (<b>1</b>), Zr (<b>2</b>)), used to sequester the coordination sphere of the central metal atom (Ba), allowed step-by-step construction of termetallic molecules [{M′(O<i>i</i>Pr)₄}­(HO<i>i</i>Pr)­Ba­{M₂(O<i>i</i>Pr)₉}] (M′ = Al (<b>3</b>), Ga (<b>4</b>), M = Hf; M′ = Al, M = Zr (<b>5</b>)). In contrast to a common “coordinative-fit” approach mainly used for bimetallic compounds, this stepwise rational construction using fast successive salt metathesis reactions circumvents general challenges in the syntheses of termetallic alkoxides by avoiding the thermodynamically preferred formation of bimetallic alkoxide molecules. The presented compounds exhibit for the first time gas phase stable termetallic alkoxide frameworks