The Binomial Distribution of Hydrogen and Deuterium in Arsanes, Diarsanes, and Triarsanes Generated from As(Iii)/[BH_nD_4-n]⁻ and the Effect of Trace Amounts of Rh(Iii) Ions

Abstract

Recent studies of the formation of arsane in the borohydride/arsenate reaction demonstrate the occurrence of condensation cascades whereby small quantities of di-and triarsanes are formed. In this study, the isotopic composition of these di-and triarsanes was examined using deuterium labelled borohydrides. A statistical model was employed to construct the mass spectra of all diarsane and triarsane isotopologues (As 2 H n D 4-n and As 3 H n D 5-n ) from the mass spectra of isotopically pure compounds (As 2 H 4 , As 2 D 4 , As 3 H 5 , and As 3 D 5 ). Subsequent deconvolution of the experimental mixed spectra shows that incorporation of hydrogen closely follows the binomial distribution, in accord with arsane formation. The H/D distribution in arsane, diarsane, and triarsane isotopologues is binomial in the absence of any interference. However, this is significantly altered by the presence of some transition metals; presented here, for the first time, are the effects of Rh(III). The presence of Rh(III) in the As(III)/ [BD 4 ] − system entails the incorporation of hydrogen into the arsanes arising from the solvent, altering the expected binomial H/D distribution.

Comment on “Understanding the effects of potassium ferricyanide on lead hydride formation in tetrahydroborate system and its application of lead in milk using hydride generation inductively coupled plasma optical emission spectrometry” by B. Deng, X. Xu, Y. Xiao, P. Zhu, Y. Wang

“…More recently, further mass spectrometric evidences [9][10][11] on arsane and methylarsane generation showed that approaching the low THB/analyte ratio, typical of "synthetic-like" conditions, several polymeric arsanes could be identified both in vapor and liquid phase and precipitation of a large mass fraction of the analyte is observed at the higher analyte concentrations employed. In the case of lead this effect could be also magnified by the change of structure of lead substrates reacting with THB, in view of the significant change of speciation of aqueous lead ions passing from micromolar to millimolar level total lead ( Fig.…”

“…The key point is that the formation of hydrides, MH n , is not a single step reaction but pass through intermediate hydrides (hydrido metal complexes, e.g., H-M-OH), which can evolve, depending on reaction conditions and analyte concentration, either to form the final hydride or to form polymeric species through condensation cascade reactions [9,10], as reported in the simplified scheme: …”