A series of high-nuclear planar equilateral triangle-shaped {Ln6(μ3-OH)6} cluster encapsulated polyoxoniobates with frequency dependent magnetic property

Abstract

The integration of lanthanide (Ln) ions and polyoxoniobates (PONbs) is challenging, and the known Ln-substituted PONbs are still scarce. This work introduces high-nuclear iso-Ln-oxo clusters into the PONb system. The first series of high-nuclear Ln-oxo clusters encapsulated heterometallic polyoxoniobates H9[Na(H2O)4][Cu(en)2]10{Ln6(μ3-OH)6(SiNb18O54)3}·18H2O (1-Ln, en = ethylenediamine, Ln = Dy, Gd, Tb, Ho, Er, Tm, Yb, Lu) based on flower-like {Ln6(μ3-OH)6(SiNb18O54)3} ({Ln6Si3Nb54}) clusters have been successfully synthesized via one-pot hydrothermal synthesis strategy. The flower-like polyoxoanion {Ln6Si3Nb54} is consisted of three heteropolyoxoniobate {SiNb18O54} clusters and one unique planar equilateral triangle-shaped {Ln6(μ3-OH)6} cluster, which presents the highest nuclear iso-Ln-oxo cluster in PONb chemistry. In {Ln6(μ3-OH)6} cluster, each pair of μ3-OH groups link three Dy3+ ions to form a small approximate equilateral triangle-shaped {Dy3(OH)2} cluster. Furthermore, the three {Dy3(OH)2} clusters comprise a bigger approximate equilateral triangle-shaped {Dy6(μ3-OH)6} cluster. The reported hexanuclear {Ln6} cluster skeletons are mostly octahedral, however, such equilateral triangle-shaped skeleton of the hexanuclear Ln-oxo cluster is first observed. The 1-Dy exhibits good water vapor adsorption capacity and ferromagnetic properties.