In‐situ Complex and Sb–N Bond Formation in an Antimonato Polyoxovanadate Reaction System

Abstract

The self‐assembly reaction towards the archetypal antimonato polyoxovanadate {V15Sb6} in the presence of two organic amines, 1‐(2‐aminoethyl)piperazine (aep) and diethylenetriamine (dien), and a simple NiII salt yields the compound {Ni(dien)2}2[(aepH)2V15Sb6O42(H2O)]·7.5H2O in which secondary [Ni(dien)2]2+ coordination complexes and covalent Sb–Naep bonds coexist. The latter augment the spherical [V15Sb6O42(H2O)]6– cluster core by two protonated aep groups that effectively reduce the polyanion's charge. The terminal NH3 groups of the two crystallographically independent aep units interlink two adjacent cluster anions through strong N–H···O interactions. In the solid state, this results in a tight 3D network of Sb–N and hydrogen bonds, which only starts to release its crystal water above 150 °C. As anticipated from its structure, the magnetic properties of the title compounds can be modeled using an additive approach.

An Exotic Layered Compound Consisting of Interconnected Arsenato‐Polyoxovanadate Clusters: Thermal and Magnetic Properties and Liquid Phase Exfoliation

“…The experimental value of 20.8 cm 3 ⋅ K ⋅ mol −1 is significantly lower indicating significant antiferromagnetic exchange interactions even at room temperature. This observation has also been made for high nuclearity POV clusters independent from the number of V 4+ and counterions, because antiferromagnetic superexchange mainly occurs within the cluster anions [21,57] …”

“…The crystal structures of such hetero‐POVs are often related to the {V 18 O 42 } cluster [2] by formal replacement of two, three or four {VO 5 } pyramids by two, three or four {E 2 O 5 } or {E′ 2 O 7 } units (E=Sb, As, E′=Si, Ge). Focusing on As and Sb, the general formulas are {V 16 E 4 O 42 }, [3–6,7,8] {V 15 E 6 O 42 } [4,5,9–18,19,20,21] and {V 14 E 8 O 42 } [6,8,10,12,13,18,20,22–35,36] . The first high‐nuclearity As‐POV was [V 15 As 6 O 42 ] 6− published in 1988, [11] and due to its unusual magnetic and electronic properties this cluster was investigated intensively [37]…”