Structure cristalline et covalence des liaisons dans le sulfate d'arsenic(III), As2(SO4)3

Abstract

As2(SO4)3 belongs to the monoclinic system, space group P2~/c, with a = 9.389 (3), b = 5.255 (2), c = 19.355 (6) .i, fl = 91.88 (2) °, V = 954.5 A, 3, Z = 4, D,, = 3.00 (5), D x = 3.05 Mg m -~. The structure has been solved at 293 K with 1922 independent reflexions (2 = 0.7107/i, 0 < 32 °) and refined to a weighted R value of 0.040. Each SO4 tetrahedron bridges two AsO3 pyramids, with two S-O bridging bond lengths near 1-54/l, the two terminal S=O bonds being shorter (1.42 A). The three As-O bonds (mean value 1.83/i) are slightly weaker than in ms40 6 (1.80~), the coordination polyhedron of As m being an AsOaE tetrahedron (As-E ~ 1.23 ~).

Structure of an oxonium antimony(III) sulphate, (H3O)2Sb2(SO4)4

“…We hope to account for the differences between SbO,,E and AsO,~ polyhedra in similar 'sulphate' compounds in terms of ionic radii and the degree of covalency of the M-O bonds (M = As, Sb). For arsenic(III) compounds such as As2(804) 3 (Douglade & Mercier, 1982), As20(SO4) 2 (Mercier & Douglade, 1982b) and As202(804) (Mercier & Douglade, 1982a) only AsO3E tetrahedra have been observed. On the other hand, in antimony 'sulphates', the coordination number of Sb is greater, and SbO4E polyhedra are often observed; e.g.…”

Missing Links in the Sulfate Chemistry of Group 15 Elements: As(S2O7)(HS2O7), Sb2(SO4)2(S2O7), and Bi2(S2O7)3 from Reactions in Oleum under Harsh Conditions

“…10–15 However, essentially basic sulfates (oxide‐sulfates, hydroxide‐sulfates) are reported, while pure sulfates or even more SO 3 ‐rich phases, i.e. disulfates, are less known and namely As 2 (SO 4 ) 3 as well as Sb 2 (S 2 O 7 ) 3 are the only examples 11a,15. With this work we provide some missing links in the sulfate chemistry of group 15 elements, especially concerning SO 3 ‐rich species.…”

Affinement de la structure avec tunnels de paires E dans un oxysulfate d'arsenic: (As2O2)(SO4)

“…La premi6re petite divergence r6side dans la liaison As-O du pont As-O-S. Cette liaison [ 1,890 (4)/~] est plus courte et donc plus covalente que pr6vue dans l'ancienne structure [1,93 (2)A]; n6an-moins, elle reste nettement sup6rieure aux longueurs des liaisons As-O dans les encha3nements As-O-As. Elle est m~me plus longue que dans les trois 'ponts' As-O-S existant autour de As dans As2(SO4)3 (Douglade & Mercier, 1982) (Mercier, 1975) (Douglade & Mercier, 1982). Les spectres Raman montrent clairement le renforcement des liaisons SO 2 'libres' par l'augmentation de la fr6quence de vibration Vs(SO2) de 1130 ~ 1160 cm -~ en passant de 1,441 ~ 1,42A.…”