Moessbauer study of stibonic and stibinic acids: structural implications from orbital population analysis

Abstract

A series of amorphous stibonic acids, RSb03H2, one stibinic acid, (p-CH3Ph)2Sb02H, and Ph3SbO have been studied by mSb Móssbauer spectroscopy. The isomer shift, , decreases almost linearly with increasing number of R groups. Both the stibonic and stibinic acids have appreciable values of as well as quadrupole coupling constants on the order of ±10 mm s'1. Using an additive model to obtain orbital populations along the Sb ligand bonds for various assumed geometries, it is concluded that the typical Sb site in the amorphous acids has approximately trigonal-bipyramidal geometry with bridging oxygens in apical positions. The orbital population along the equatorial Sb-OH bond, 0 , is appreciably larger than the apical 0 in Ph4SbOH.

Well‐Defined Stibonic and Tellurinic Acids

“…[3] Unlike their lighter Group 15 and 16 congeners, all hitherto described stibonic and tellurinic acids are ill-defined, amorphous, high-melting compounds that are poorly soluble in most organic solvents. Molecular weight determinations [4] and 121 Sb Mössbauer spectroscopic studies [5] confirm a high degree of aggregation and a trigonalbipyramidal structure for PhSb(O)(OH) 2 . By contrast, all phosphonic and arsonic acids RE(O)(OH) 2 (E = P, As), as well as sulfinic and seleninic acids RE(O)(OH) (E = S, Se), are well-defined molecular compounds with tetrahedrally coordinated central atoms E, polar (formal) E = O double bonds and E À OH groups that are usually involved in intermolecular hydrogen bonding in the solid state.…”

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

“…Mossbauer studies have been interpreted in terms of five-coordinate Sb [3]. Very recently, an example with a very bulky aryl group has been reported as an oxygenbridged dimer, (2,6-Mes 2 C 6 H 3 Sb) 2 O 2 (OH) 4 [4].…”

“…2 Mo¨ssbauer studies have been interpreted in terms of fivecoordinate Sb. 3 Very recently, an example with a very bulky aryl group has been reported as an oxygen-bridged dimer, (2,6-Mes 2 C 6 H 3 Sb) 2 O 2 (OH) 4 . 4 We now report ESI-MS data for some arylstibonic acids which indicate high-nuclearity aggregation and show that these are a source of a novel class of well-defined polyoxometallates.…”

Wohldefinierte Stibonsäuren und Tellurinsäuren

“…[3] Im Unterschied zu ihren leichteren Homologen der Gruppen 15 und 16 sind alle bisher beschriebenen Stibon-und Tellurinsäuren schlecht definierte, amorphe, hochschmelzende Substanzen, die nur eine geringe Löslichkeit in den meisten organischen Lösungsmitteln aufweisen. Molmassenbestimmungen [4] und 121 Sb-Mößbauer-Spektroskopiestudien [5]…”

“…[12] 2.035(2) ) nur geringfügig um 0.122(2) und sind gut mit denen von (Ph 3 SbO) 2 (1.928(3) und 2.071(4) ) vergleichbar. [6] Dagegen unterscheiden sich die äquatorialen und axialen endocyclischen Te-O-Bindungslängen in 6 (1.897(5) und 2.143(5) ) um 0.246 (5) . Im verwandten (Ph 2 TeO) 2 unterscheiden sich die äquatorialen und axialen Te-O-Bindungslängen (Mittelwerte: 1.89(1) und 2.55(1) ) noch ausgeprägter, nämlich um 0.66 (1) .…”