Reverse-Keggin Ions:  Polycondensation of Antimonate Ligands Give Inorganic Cryptand

Abstract

Reverse-Keggin ions are reported in which a p-block element (antimony) occupies the twelve vertices of a truncated tetrahedron while a d-block element (manganese or zinc) occupies the tetrahedral central cavity. The exterior of the reverse-Keggins also acts as tridentate ligands to further d-block centers.

Arylstibonic acids [H8(RSb)12O28]; precursors to organometallic isopolyoxostibonates [Na2H9(RSb)12O30]−, (R = aryl)

“…This was soluble in MeCN and an ESI-MS of the resulting solution gave the 20 spectrum shown in Fig 1. The dominant peak can be unambiguously assigned to [H 7 (RSb) 12 37 Cl 25%) match perfectly. There was also the corresponding doubly-charged peak for [H 6 (RSb) 12 O 28 ] 2-(m/z 1626.379, calc. 1626.375).…”

“…There is a difference in the apparent degree of hydration of the core-cluster unit between the ESI-MS results in MeCN, which indicate a parent formula [H 8 (RSb) 12 O 28 ], and the crystal structure result which is derived from [H 12 (RSb) 12 This serves as a parent for a novel range of isopolyoxostibonates, stable under alkaline conditions (it is noteworthy that transition-metal POMs form under acid conditions). The cage behaves as an inorganic crown ligand, with a strong affinity for Na + and other similarlysized cations.…”

“…If the stibonic acid is not carefully purified, or if a small amount of NaOH is added**, or even if the solution of the purified sample is left standing in normal glassware, the parent acid peaks are completely replaced by those of the sodium adducts [Na 3 H 3 (RSb) 12 , there are also many other water molecules in the lattice which are poorly defined, as is common in structures of this type. 5 The anion is a cage formed by twelve hexa-coordinate R"Sb groups at the apices of a hexagonal antiprism, linked by O atoms.…”

Assembling anionic Sb(v)/(iii) containing polyoxostibonates stabilized by triphenyltellurium cations

“…6 The first report on POMs based on organoantimony was in 2007 wherein organostibonic acids were used as starting materials for building POM frameworks encapsulating transition metal ions (Mn or Zn) in their cavity. 7 Organostibonic acids are illdefined, high molecular weight polymers whose solid state structure has been a matter of considerable debate. 8 Recently, controlled hydrolysis of 2,6-Mes 2 C 6 H 3 SbCl 4 under basic conditions leading to the isolation of the first molecular arylstibonic acid which crystallized as a dimer in the solid state has been reported.…”

Preparation and molecular structure of the dimeric arylstibonic monoethylester [2,6-Mes2C6H3Sb(O)(OEt)(OH)]2

“…However, recently, the research groups of Winpenny (Baskar et al, 2007;Ali et al, 2008), Nicholson (Clark et al, 2009;Nicholson et al, 2010Nicholson et al, , 2011Nicholson et al, , 2012, Kortz (Piedra-Garza et al, 2009), and Baskar (Prabhu et al, 2009;Jami et al, 2010;Jami and Baskar, 2012) developed powerful strategies to build up discrete clusters and well-defined polyoxometalates based on arylstibonic acids by breaking down the random polymeric structures into smaller aggregates or by generating mononuclear arylantimony oxo moieties in situ using aryl cleavage reactions. Our strategy to avoid extensive aggregation in arylstibonic acids involved the kinetic stabilization provided by a bulky m -terphenyl substituent.…”