Icosaniobate:  A New Member of the Isoniobate Family

Abstract

Icosaniobate [Nb20O54]8- was synthesized by reacting [H4Nb6O19]4- with NO in tetrahydrofuran or MeNO2. A single-crystal X-ray diffraction study of its n-tetrabutylammonium salt [a = 17.7284(18) A, b = 33.542(3) A, c = 34.316(2) A, Z = 4, and space group P22(1)2(1)] revealed a dimeric structure where two decaniobate ions are condensed sharing two terminal O atoms. Unlike that in [(NbW5O18)2O]4-, the Nb-O-Nb bridges in icosaniobate are bent. The nonlinear bridging reduces the maximum possible symmetry of the dimeric anion to mm2, which it closely approximates.

Building Niobate Nanoparticles with Hexaniobate Lindqvist Ions

“…In previous reports in the literature, [30,[36][37][38][39][40] a simple method was reported to prepare hexaniobate ions in aqueous solution. Briefly, it was to dissolve amorphous Nb 2 O 5 ·xH 2 O in a strongly basic aqueous solution of inorganic alkali hydroxides (e.g.…”

“…8-, the most dominant and smallest of its kind, [30] has been well studied and used as the standard architecture for heteropolyniobates. [30,[36][37][38][39][40] 8-. [41,42] In this article, we present a general method to build niobate NPs by using hexaniobate ions as a niobium source.…”

Reactivity of Polyoxoniobates in Acidic Solution: Controllable Assembly and Disassembly Based on Niobium‐Substituted Germanotungstates

“…[1][2][3] Unlike POMs based on molybdenum or tungsten, which have been well examined under acidic conditions, [4] the study of polyoxoniobates have been dominated for a very long time by the Lindquist [Nb 6 O 19 ] 8À ion, which exists only under alkaline conditions, forming Nb 2 O 5 precipitates under acidic conditions, and this has severely restricted the development of polyoxoniobates. [5] However, great progress has been made in polyoxoniobate chemistry in recent years owing to the discovery and development of heteropolyniobates by Nyman and co-workers, [6] the research presented by Casey and co-workers, [7] and the recent reports on [Nb 20 O 54 ] 8À , [8] [H 9 Nb 24 O 72 ] 15À , [9] [Nb 7 O 22 ] 9À , [10a] [{Cu-A C H T U N G T R E N N U N G (H 2 O)L} 2 (CuNb 11 O 35 H 4 )] 5À (L = 1,10-phenanthroline, 2,2'-bipyridine), [10b] [HNb 27 O 76 ] 16À and [H 10 Nb 31 O 92 A C H T U N G T R E N N U N G (CO 3 )] 23À . [11] However, the development of polyoxoniobate chemistry is still at an early stage and is dominated by reactions performed under alkaline and mainly hydrothermal conditions.…”

Giant Polyniobate Clusters Based on [Nb7O22]9− Units Derived from a Nb6O19 Precursor

“…Moreover, Yagasaki et al obtained a dimeric isopolyanion [Nb 20 O 54 ] 8À . [16] Although polyniobate chemistry has made progress to some extent in the preparation and characterization of some novel compounds, the systematic synthesis and property investigation of these systems remain less developed. Furthermore, the polyniobate family attracts perpetual interest for a vast range of potential applications in virology, [3c] nuclear-waste treatment, [9g, 23a] and the base-catalyzed decomposition of biocontaminants, [17b] resulting from their unique characteristics in structure (high charge/surface ratio) and properties (basicity).…”