Heterometallic 3d-4f Alkoxide Precursors for the Synthesis of Binary Oxide Nanomaterials.

In this study, a new method for the synthesis of heterometallic 3d-4f alkoxides by the direct reaction of metallic lanthanides (La, Pr, Nd, Gd) with MCl 2 (M = Mn, Ni, Co) in 2-methoxyethanol was developed. The method was applied to the synthesis of the heterometallic oxo-alkoxide clusters [Ln 4 Mn 2 (μ 6 -O)(μ 3 -OR) 8 (HOR) x Cl 6 ] (Ln = La ( 1 ), Nd ( 2 ), Gd ( 3 ); x = 0, 2, 4); [Pr 4 M 2 (μ 6 -O)(μ 3 -OR) 8 (HOR) x Cl 6 ] (M = Co ( 4 ), Ni ( 5 ); x = 2, 4); and [Ln 4 Mn 2 (μ 3 -OH) 2 (μ 3 -OR) 4 (μ-OR) 4 (μ-Cl) 2 (HOR) 4 Cl 6 ] (Ln = La ( 11 ) and Pr ( 12 )). Mechanistic investigation led to the isolation of the homo- and heterometallic intermediates [Pr(μ-OR)(μ-Cl)(HOR)Cl] n ( 6 ), [Co 4 (μ 3 -OR) 4 (HOR) 4 Cl 4 ] ( 7 ), [Ni 4 (μ 3 -OR) 4 (HOEt) 4 Cl 4 ] ( 8 ), [Mn 4 (μ 3 -OR) 4 (HOR) 2 (HOEt) 2 Cl 4 ] ( 9 ), and [Nd(HOR) 4 Cl][CoCl 4 ] ( 10 ). In the presence of an external M(II) source at 1100 °C, 1 - 4 and 12 were selectively converted into binary metal oxide nanomaterials with trigonal or orthorhombic perovskite structures, i.e., LaMnO 3 , GdMnO 3 , NdMnO 3 , Pr 0.9 MnO 3 , and PrCoO 3 . Compound 5 decomposed into a mixture of homo- and heterometallic oxides. The method presented provides a valuable platform for the preparation of advanced heterometallic oxide materials with promising magnetic, luminescence, and/or catalytic applications.