Reactions with Oleum under Harsh Conditions: Characterization of the Unique [M(S₂O₇)₃]²⁻ Ions (M=Si, Ge, Sn) in A₂[M(S₂O₇)₃] (A=NH₄, Ag)

Abstract

The reactions of group 14 tetrachlorides MCl(4) (M=Si, Ge, Sn) with oleum (65% SO(3)) at elevated temperatures lead to the unique complex ions [M(S(2)O(7))(3)](2-), which show the central M atoms in coordination with three chelating S(2)O(7)(2-) groups. The mean distances M-O within the anions increase from 175.6(2)-177.5(2) pm (M=Si) to 186.4(4)-187.7(4) pm (M=Ge) to 201.9(2)-203.5(2) pm (M=Sn). These distances are reproduced well by DFT calculations. The same calculations show an increasing positive charge for the central M atom in the row Si, Ge, Sn, which can be interpreted as the decreasing covalency of the M-O bonds. For the silicon compound (NH(4))(2)[Si(S(2)O(7))(3)], (29)Si solid-state NMR measurements have been performed, with the results showing a signal at -215.5 ppm for (NH(4))(2)[Si(S(2)O(7))(3)], which is in very good agreement with theoretical estimations. In addition, the vibrational modes within the [MO(6)] skeleton have been monitored by Raman spectroscopy for selected examples, and are well reproduced by theory. The charge balance for the [M(S(2)O(7))(3)](2-) ions is achieved by monovalent A(+) counter ions (A=NH(4), Ag), which are implemented in the syntheses in the form of their sulfates. The sizes of the A(+) ions, that is, their coordination requirements, cause the crystallographic differences in the crystal structures, although the complex [M(S(2)O(7))(3)](2-) ions remain essentially unaffected with the different A(+) ions. Furthermore, the nature of the A(+) ions influences the thermal behavior of the compounds, which has been monitored for selected examples by thermogravimetric differential thermal analysis (DTA/TG) and XRD measurements.

Palladium(IV) in an Oxoanionic Environment: The XeF2 Assisted Synthesis of [Pd(S2O7)3]2−

“…[13] In 2À type complexes for the metals (M) germanium, tin, titanium, and even for silicon, representing a rarely seen example of octahedral Si IV coordination with inorganic oxo-ligands. [14] With respect to these findings we argued that this type of complex should also be a suitable candidate for the stabilization of tetravalent palladium. According to our previous findings oxidation of elemental palladium or Pd II by SO 3 cannot be expected.…”

“…From the quantum chemical calculations also the expected vibrational frequencies could be extracted so that an assignment of (13) the bands observed in both IR and Raman spectrum were possible ( Figure S4, Table S9 2À type complexes most of the normal modes are complex combination vibrations. [13,14] The thermal decomposition of K 2 [Pd(S 2 O 7 ) 3 ] is a threestep process ( Figure S5, Table S10) and leads finally to a mixture of K 2 SO 4 and elemental palladium. Note that the last step of the degradation can be clearly attributed to the decomposition of PdO.…”

Bis(tetrasulfato)palladat, [Pd(S4O13)2]2−

“…[10] [a] S1-O11 147.9 [b] 142.0 S1-O12 [13] ), Strukturlçsung mit Direkten Methoden, Full-matrix-least-squares-Verfeinerung (170 Parameter) gegen j F 2 j , (mit den Programmen SHELXS-97 und SHELXL-97 [14] ), …”

Reaction with SO3 in Ionic Liquids: The Example of K2(S2O7)­(H2SO4)

“…We were able to present several unprecedented disulfates like B[M(S 2 O 7 ) 3 ] (B = Sr, Ba, Pb, M = Si, Ge), [1] + chains. [2][3][4] All of these compounds were obtained via reactions in oleum and very seldom a higher polysulfate has been obtained under these conditions. The trisulfate Pb(S 3 O 10 ) is one of the few examples.…”

“…The trisulfate Pb(S 3 O 10 ) is one of the few examples. [5] In order to prepare even higher polysulfates we expanded our research to reactions with neat SO 3 , which lead us to partly unprecedented new sulfates and polysulfates. In this way we obtained the first palladium disulfate, Pd(S 2 O 7 ), in which the octahedral oxygen coordination of palladium leads to a ferromagnetic behavior at low temperature.…”