Anion-Dependent Assembly of Heterometallic 3d-4f Clusters Based on a Lacunary Polyoxometalate

Inorg Chem. 2017 Jul 17;56(14):8439-8445. doi: 10.1021/acs.inorgchem.7b01104. Epub 2017 Jun 26.

Abstract

A series of heterometallic 3d-4f clusters, formulated as Na17[Ln3(H2O)5NiII(H2O)3(Sb4O4)(SbW9O33)3(NiIIW6O24)(WO2)3(CH3COO)]·(H2O)65 [abbreviated as Ln3Ni2, where Ln = La3+ (1), Pr3+ (2), and Nd3+ (3)], K5Na11[Ln3(H2O)3NiII3(H2O)6(SbW9O33)3(WO4)(CO3)]·(H2O)40 [abbreviated as Ln3Ni3, where Ln = La3+ (4), Pr3+ (5), and Nd3+ (6)], and K3Na27[Ln3NiII93-OH)9(SbW9O33)2(PW9O34)3(CH3COO)3]·(H2O)80 [abbreviated as Ln3Ni9, where Ln = Dy3+ (7) and Er3+ (8)], were obtained through the reaction of the lacunary {SbW9O33} precursor with Ln(NO3)3·6H2O and NiCl2·6H2O in a NaAc/HAc buffer in the presence of different anions. Single-crystal X-ray structure analysis revealed that compounds 1-3 possessed tetrameric architectures featuring three Keggin-type {SbW9O33} and one Anderson-type {NiIIW6O24} building blocks encapsulating one {Sb4O4} cluster, three WO2 units, three Ln3+ metal ions, and two Ni2+ metal ions. Compounds 4-6 displayed cyclic trimeric aggregates of three {SbW9O33} units enveloping one CO32--templated trinuclear [Ln3(CO3)]7+ and one WO42--templated [NiII3(WO4)]+ unit. Compounds 7 and 8 exhibited unique pentameric architectures that featured three 3d-4f cubane clusters of {LnNi33-OH)3} capped by two {SbW9O33} and three {PW9O34} building blocks. Interestingly, the structural regulation of the heterometallic 3d-4f clusters in the polyoxometalate systems with trimers, tetramers, and pentamers was realized by introducing different anions.