Expansion of Zirconium Oxide Clusters by 3d/4f Ions.

Two series of charge-neutral coordination clusters featuring quasi-isostructural metal oxide cores, isolated as [ZrFeLnO(ib)(bda)(NO)]·MeCN (Ln = La (), Ce (), Pr (), and Nd (); ib = isobutyrate; Hbda = -butyldiethanolamine) and [ZrFeLnO(ib)(mda)(NO)]·MeCN (Ln = La (), Ce (), Pr (), and Nd (); Hmda = -methyldiethanolamine), were obtained via one-pot reactions of [FeO(ib)(HO)]NO as a critical precursor, Ln(NO)·6HO (Ln = La, Ce, Pr, and Nd), the respective aminoalcohol, and [ZrO(OH)(ib)(HO)]·3Hib in an acetonitrile solution. The coordination clusters in - feature {ZrO} cores that are structurally expanded by two 4f (Ln) and two 3d (Fe) metal ions, each individually coordinated to one of the eight oxide centers of {ZrO}, producing a metal skeleton where the 3d/4f positions cap four of the triangular faces of the central Zr octahedron. The coordination clusters differ in the chosen aminoalcohol coligands, -butyldiethanolamine or -methyldiethanolamine, which lead to a different isobutyrate coordination pattern in the two series, while the {FeLnZrO} core structure remains virtually unaffected. All eight coordination clusters are obtained in moderate to good yields of 29-66% after only several days. Complexes - are stable against air and moisture; they are also surprisingly thermally stable up to 280 °C in air and in nitrogen atmosphere, and they represent the first reported examples of 3d/4f-functionalized zirconium oxide clusters.