Ferromagnetic Ordering in the Layer‐Structured Pd(HS2O7)2

The reaction of (NO₂)(CF₃SO₃) and elemental palladium in oleum (65 % SO₃) leads to violet single crystals of Pd(HS₂O₇)₂ (monoclinic, P2₁/c, Z=2, a=927.80(9), b=682.58(7), c=920.84(9) pm, β=117.756(2)°, wR₂=0.0439). In the crystal structure, the Pd²⁺ ions show an uncommon octahedral coordination of six oxygen atoms belonging to six HS₂O₇^? ions. The linkage of [PdO₆] octahedra and the hydrogendisulfate anions leads to a layer structure, and the layers are held together by hydrogen bonds. The unusual coordination of the Pd²⁺ ions results in an electronic d⁸ high‐spin configuration, which leads to the paramagnetic behavior of the compound. Moreover, at low temperature, a ferromagnetic ordering was observed with a Curie temperature of 8 K.     

Towards Polysulfuric Acids: The Hydrogentrisulfate Anion [HS3O10]− in A[HS3O10] (A=Na,K, Rb)

The reaction of Na₂SO₄ and K₂SO₄ with fuming sulfuric acid (65 % SO₃) yielded colorless extremely sensitive crystals of Na[HS₃O₁₀] (monoclinic; P2₁/n (No. 14); Z=4; a=707.36(2), b=1378.56(4), c=848.10(3) pm; β=94.817(1)°; V=824.09(4) ? 10⁶ pm³) and K[HS₃O₁₀] (orthorhombic; Pccn (No. 56); Z=4; a=1057.16(3), b=807.81(2), c=897.57(2) pm; V=766.51(3) ? 10⁶ pm³). The analogous rubidium compound Rb[HS₃O₁₀] (orthorhombic; Pnma (No. 62); Z=4; a=891.43(3), b=1095.34(4), c=839.37(3) pm; V=819.58(5) ? 10⁶ pm³) originates from the reaction of Rb₂CO₃ and SO₃. All of the different structures contain the hitherto unknown anion [HS₃O₁₀]^? and are stamped by strong hydrogen bonds linking the anions either to dimers or chains. Theoretical investigations by DFT methods give further insight in the structural characteristics of [HS₃O₁₀]^?. The preparation of the [HS₃O₁₀]^? anion can be seen as an important milestone on our way to the still elusive polysulfuric acids.     

Oxidizing Elemental Platinum with Oleum under Harsh Conditions: The Unique Tris(disulfato)platinate(IV) [Pt(S2O7)3]2− Anion

For the first time, direct oxidation of elemental platinum by a mineral acid to its tetravalent state was observed in course of the reaction of platinum with oleum (65 % SO₃) in the presence of barium carbonate. The reaction has been carried out in torch‐sealed glass ampoules at 160 °C and gave yellow single crystals of Ba[Pt(S₂O₇)₃](H₂SO₄)_0.5(H₂S₂O₇)_0.5 (triclinic, P$\bar 1$ , Z=2, a=992.05(2), b=1069.07(3), c=1114.22(3) pm, α=69.49(7), β=72.96(2), γ=72.93(1)°, V=1033.95(5) ų). The structure of Ba[Pt(S₂O₇)₃](H₂SO₄)_0.5(H₂S₂O₇)_0.5 exhibits the unique tris‐(disulfato)‐platinate anion [Pt(S₂O₇)₃]^2? with three chelating disulfate groups coordinated to the platinum atom. Charge balance is achieved by the Ba²⁺ ions, which are coordinated by (S₂O₇)^2? groups from the platinate complex and by disordered sulfuric acids and disulfuric acid molecules. Thermal decomposition of the bulk material revealed elemental platinum and barium sulfate as decomposition residual.     

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

For the first time tetravalent palladium is detected, coordinated exclusively by simple oxoanions. Stabilization was achieved by formation of the [Pd(S₂O₇)₃]^2? complex in which three chelating disulfate groups surround the metal atom. The salt K₂[Pd(S₂O₇)₃] could only be obtained if the reaction of K₂[PdCl₆] and neat SO₃ was performed in the presence of XeF₂.     

From Infinite Chains according to 1∞[Zr(S2O7)4/2] in Zr(S2O7)2 to the unprecedented [Zr(S2O7)4]4– Anion in Ag4[Zr(S2O7)4]

The reaction of ZrCl₄ with oleum (65 % SO₃) in the presence of Ag₂SO₄ at 250 °C yielded colorless single crystals of Zr(S₂O₇)₂ [orthorhombic, Pccn, Z = 4, a = 709.08(6) pm, b = 1442.2(2) pm, c = 942.23(9) pm, V = 963.5(2) × 10⁶ pm³]. Zr(S₂O₇)₂ shows Zr⁴⁺ ions in an eightfold distorted square antiprismatic coordination of oxygen atoms belonging to four chelating disulfate units. Each S₂O₇^2– ion is connected to a further Zr⁴⁺ ion leading to chains according to ¹_∞[Zr(S₂O₇)_4/2]. The same reaction at a temperature of 150 °C resulted in the formation of Ag₄[Zr(S₂O₇)₄] [monoclinic, C2/c, Z = 4, a = 1829.35(9) pm, b = 704.37(3) pm, c = 1999.1(1) pm, β = 117.844(2)°, V = 2277.6(2) × 10⁶ pm³]. Ag₄[Zr(S₂O₇)₄] exhibits the unprecedented [Zr(S₂O₇)₄]^4– anion, in which the central Zr⁴⁺ cation is coordinated by four chelating disulfate units. Thus, in Ag₄[Zr(S₂O₇)₄] the ¹_∞[[Zr(S₂O₇)_4/2] chains observed in Zr(S₂O₇)₂ are formally cut into pieces by the implementation of Ag⁺ ions.     

Synthesis and X-ray and Spectral Study of the Compounds [Q4N]2[Fe2(S2O3)2(NO)4] (Q = Me,Et, n-Pr,n-Bu)

Iron nitrosyl complexes with general formula [Q₄N]₂[Fe₂(S₂O₃)₂(NO)₄] (Q = Me, Et, n-Pr, n-Bu) were synthesized by the exchange reaction of K₂[Fe₂(S₂O₃)₂(NO)₄] with tetraalkylammonium bromides. The molecular and crystal structure of [(CH₃)₄N]₂[Fe₂(S₂O₃)₂(NO)₄] were studied by X-ray diffraction analysis. The iron atom in the four-membered cycle of the [2Fe–2S] anion is bound to another Fe atom and to two sulfur atoms and is coordinated by two nonequivalent NO groups, each bridging sulfur atom being bound to the SO₃group. The structurally equivalent iron atoms are in the state Fe^1–(S= 1/2). The Mössbauer spectroscopy method shows that the complexes are diamagnetic due to the strong Fe–Fe bond. It is found that the SO₃group provides higher stability of the thiosulfate anion than the anion in Roussin's red salt [Fe₂S₂(NO)₄]^2–.     

Synthesis and Crystal Structure of the Palladium(IV) Polyoxomolybdate,K0.75Na3.75[PdMo6O24H3.5]·17H2O

The first example of a heteropolyoxomolybdate containing palladium(IV) was isolated and characterized by X‐ray crystallography. The palladium(IV) hexamolybdate, K_0.75Na_3.75[PdMo₆O₂₄H_3.5]·17H₂O, was isolated from an aqueous solution at pH 4.5 in the space group P\bar{1} , a 10.790(2), b 12.244(3), c 14.086(3) Å, α 113.77(1), β 90.41(1),γ 107.86(1)°, and the structure was determined using X‐ray diffraction methods, refining to a residual of 0.0301 for 5334 reflections. A formal “[PdMo₆O₂₄H₃]^5–” subunit exhibits the basic Anderson structure, with two [PdMo₆O₂₄H₃]^5– cluster anions in the structure bridged by a hydrogen atom (formally an H⁺) situated on a center of symmetry to give a “[Pd₂Mo₁₂O₄₈H₇]^9–” dimeric anion. The palladium(IV) atom occupies a slightly distorted octahedral environment, with Pd–O distances ranging from 1.968 to 2.009 Å.     

Synthesis and Characterization of the Trisulfate Pb[S3O10] and Theoretical Analysis of H2S3O10

The reaction of (NH₄)₂PbCl₆ and fuming sulfuric acid (65 % SO₃) in a sealed glass tube at 250 °C led to colorless single crystals of Pb[S₃O₁₀] (orthorhombic, Pbcn, Z = 4, a = 10.9908(4), b = 8.5549(3), c = 8.0130(3) Å, V = 753.42(5) ų). The compound shows a three‐dimensional linkage of the tenfold oxygen coordinated Pb²⁺ ions and exhibits the unusual trisulfate anion, [S₃O₁₀]^2–, that consists of three vertex connected [SO₄] tetrahedra. The distances S–O within the S–O–S bridges of the anion are remarkable asymmetric with distances of 155 and 169 pm, respectively. This structural feature is well reproduced by calculations on a PBE0/cc‐pVTZ and a MP2/cc‐pVTZ level of theory. Similar calculations allow also for an inspection of the yet unknown corresponding acid, H₂S₃O₁₀. Also for this acid non‐symmetric S–O–S bridges are predicted. The thermal behavior of Pb[S₃O₁₀] is characterized by the loss of two equivalents of SO₃ at low temperature and the decomposition of intermediate Pb[SO₄] at higher temperature.     

{[Ba2(C2O4)(H2O)6](NCS)2}n: a layered mixed‐anion barium oxalate

We present the first example of a compound containing Ba²⁺, C₂O₄²⁻, water and some additional halide or pseudo‐halide anions, viz. hexa‐μ₂‐aqua‐μ₆‐oxalato‐dibarium(II) diiso­thio­cyanate, {[Ba₂(C₂O₄)(H₂O)₆](NCS)₂}_n. The structure consists of positively charged planar covalent layers of Ba²⁺ cations, oxalate anions and water mol­ecules. The first coordination sphere of the Ba²⁺ cation contains six water mol­ecules and four O atoms from two planar oxalate anions. The oxalate anion lies on an inversion centre and is coordinated to six Ba²⁺ cations, each donor O atom being bonded to two cations. Pairs of water mol­ecules are coordinated by two Ba²⁺ cations. The layers are interspersed with non‐coordinated NCS⁻ anions.     

The Unprecedented Tetrakis‐(disulfato)‐silicate Anion [Si(S2O7)4]4−, its Germanium Congener [Ge(S2O7)4]4−, and the Tris‐(disulfato)‐metallates [M(S2O7)3]2− (M=Si,Ge, Ti), Stabilized by Divalent Counter Cations B2+ (B=Sr,Ba, Pb)

The reaction of oleum (65 % SO₃) with the tetrachlorides of silicon, germanium, and titanium, respectively, led to the complex disulfates Sr₂[M(S₂O₇)₄] (M=Si, Ge), Ba[M(S₂O₇)₃] (M=Si, Ge, Ti) and Pb[M(S₂O₇)₃] (M=Ge, Ti) if strontium, barium, and lead were used as divalent counter cations. The strontium compounds exhibit the unique tetrakis‐(disulfato)‐metallate anions [M(S₂O₇)₄]^4? with the silicon and germanium atoms in octahedral coordination of two chelating and two monodentate disulfate groups. All of the other compounds display tris‐(disulfato)‐metallate anions [M(S₂O₇)₃]^2? with three chelating disulfate groups surrounding the M atoms. Thermoanalytical investigations on the germanium compounds Sr₂[Ge(S₂O₇)₄] and Ba[Ge(S₂O₇)₃] revealed their decomposition in multi‐step processes leading to a mixture of BSO₄ and BGe₄O₉ (B=Sr, Ba), while the thermal degradation of Pb[Ti(S₂O₇)₃] yields PbTiO₃. For selected examples, IR data are additionally presented.     

Crystal structure of NaBa2[Co(Edta)]2(ClO4)3 · 9H2O

Crystals of Ba Na ethylenediaminetetraacetatocobaltate(III) perchlorate, NaBa₂[Co(Edta)]₂(ClO₄)₃ · 9H₂O, contain two crystallographically nonequivalent Ba²⁺ cations and two complex cations [Co(Edta)]^? (Edta^4? is ethylenediaminetetraacetic acid anion), the latter anions showing opposite chirality. The nearest surrounding of the Ba²⁺ ions involves three water molecules (including two bridging water molecules), six O atoms of four complexes [Co(Edta)]^? and the perchlorate O atom. Tetrameric fragments Ba₂(H₂O)₄[Co(Edta)]₂(ClO₄)₂ are united through the Ba-O bonds into layers with the Ba atoms in the middle of the layers and the perchlorate ions and complex anions at the periphery; in the latter anions, noncoordinated O atom of one of the R-metallocycles is directed outside. The Na atom of the Na(H₂O)(ClO₄) group located between the layers is bonded to these O atoms of the neighboring layers.     

Peroxofluorokomplexe der Übergangsmetalle. IX. Kristallstruktur von Ba3[Ti(O2)F5]2 · 2 H2O

Transition Metal Peroxofluoro Complexes. IX. Crystal Structure of Ba₃[Ti(O₂)F₅]₂ · 2 H₂O The pale yellow hydrat Ba₃[Ti(O₂)F₅]₂ · 2 H₂O crystallizes tetragonal (space group P4₂/mbc, a = 1 248.5(3), c = 812.2(2) pm; Z = 4; R = 0.026 for 404 independent reflections). It contains isolated [Ti(O₂)F₅]^3? anions. Thermal decomposition leads directly to α-Ba₃Ti₂O₂F₁₀, which is isotypic to α-Ba₃Al₂F₁₂.     

Dimers and Chains of Hydrogen bonded [HS2O7]– Anions in the Crystal Structures of M[HS2O7] (M = K, [NH4], [NO], Rb,Cs)

The reactions of KCl, [NH₄]₂[SO₄], Rb₂[CO₃], and Cs₂[CO₃] with fuming sulfuric acid (65 % SO₃) yielded colorless and moisture sensitive crystals of K[HS₂O₇] (monoclinic, P2₁/c (no. 14), Z = 4, a = 716.67(3) pm, b = 1043.57(4) pm, c = 828.78(3) pm, β = 107.884(1)°, V = 589.89(4) × 10⁶ pm³), [NH₄][HS₂O₇] (monoclinic, P2₁/c (no. 14), Z = 4, a = 729.29(1) pm, b = 1079.73(1) pm, c = 843.26(1) pm, β = 106.397(1)°, V = 637.01(1) × 10⁶ pm³), Rb[HS₂O₇] (monoclinic, P2₁/c (no. 14), Z = 4, a = 724.49(2) pm, b = 1073.19(3) pm, c = 852.01(3) pm, β = 106.534(1)°, V = 635.06(3) × 10⁶ pm³), and Cs[HS₂O₇] (triclinic, P$\bar{1}$ (no. 2), Z = 2, a = 537.61(3) pm, b = 784.71(4) pm, c = 867.93(4) pm, α = 94.214(2)°, β = 103.138(2)°, γ = 105.814(2)°, V = 339.47(3) × 10⁶ pm³). Colorless crystals of [NO][HS₂O₇] (monoclinic, P2₁/c (no. 14), Z = 4, a = 739.90(4) pm, b = 1048.00(5) pm, c = 830.97(4) pm, β = 106.985(2)°, V = 106.985(2) × 10⁶ pm³) were obtained as a side product from the reaction of [NH₄]₂[Rh(NO₂)₄] with oleum (65 % SO₃) in the ionic liquid [BMIm][OTf]. The crystal structures of K[HS₂O₇], [NH₄][HS₂O₇], [NO][HS₂O₇], and Rb[HS₂O₇] show the [HS₂O₇]^– ions linked into dimers by strong hydrogen bonds. Contrastingly, in the crystal structure of Cs[HS₂O₇] the [HS₂O₇]^– ions are connected to infinite chains. Raman spectra were recorded for M[HS₂O₇] (M = K, Rb, Cs).     

Crystal Structures of (PPh3)2Pd(N3)2, (AsPh3)2Pd(N3)2, (2‐Chloropyridine)2Pd(N3)2, [(AsPh4)2][Pd2(N3)4Cl2], [(PNP)2][Pd(N3)4], [(AsPh4)2][Pt(N3)4] · 2 H2O,and [(AsPh4)2][Pt(N3)6]

The crystal structures of the monomeric palladium(II) azide complexes of the type L₂Pd(N₃)₂ (L = PPh₃ ( 1 ), AsPh₃ ( 2 ), and 2‐chloropyridine ( 3 )), the dimeric [(AsPh₄)₂][Pd₂(N₃)₄Cl₂] ( 4 ), the homoleptic azido palladate [(PNP)₂][Pd(N₃)₄] ( 5 ) and the homoleptic azido platinates [(AsPh₄)₂][Pt(N₃)₄] · 2 H₂O ( 6 ) and [(AsPh₄)₂][Pt(N₃)₆] ( 7 ) were determined by X‐ray diffraction at single crystals. 1 and 2 are isotypic and crystallize in the triclinic space group P1. 1 , 2 and 3 show terminal azide ligands in trans position. In 4 the [Pd₂(N₃)₄Cl₂]^2– anions show end‐on bridging azide groups as well as terminal chlorine atoms and azide ligands. The anions in 5 and 6 show azide ligands in equal positions with almost local C_4h symmetry at the platinum and palladium atom respectively. The metal atoms show a planar surrounding. The [Pt(N₃)₆]^2– anions in 7 are centrosymmetric (idealized S₆ symmetry) with an octahedral surrounding of six nitrogen atoms at the platinum centers.     

Solvothermal Synthesis, Crystal Structure, and Properties of the New Oxothiomolybdate Ni(dien)2[Mo2O2S6]

Summary.  The reaction of NiCl₂ · 6H₂O, Na₂MoO₄ ċ 2H₂O, and sulfur in a mixture of diethylenetriamine and 0.2 M ammonia solution (1:4) under solvothermal conditions leads to the formation of orange-red crystals of the oxothiomolybdate Ni(dien)₂[Mo₂O₂S₆] (dien = diethylenetriamine) in nearly 100% yield. The structure consists of [Ni(dien)₂]²⁺ cations and discrete dimeric [Mo₂O₂S₆]²⁻ anions. The compound crystallizes in the monoclinic space group P2₁/c (a = 8.726(2), b = 18.111(4), c = 14.419(3) ?, β = 101.686(3)°). Upon heating the compound decomposes in a single step starting at about 250°C. The final decomposition product was identified by X-ray powder diffractometry as MoS₂ and Ni₃S₂. Spectroscopic data as well as detailed synthetic procedures for Ni(dien)₂[Mo₂O₂S₆] are reported. Received November 6, 2000. Accepted November 17, 2000     

Conformational change induced by hydration: trans‐dichloro­bis­[(1R,2R,3R,5S)‐(–)‐isopinocampheylamine]palladium(II) and trans‐dichloro­bis[(1S,2S,3S,5R)‐(+)‐isopinocampheylamine]palladium(II) hemihydrate

The title compounds, trans‐dichloro­bis[(1R,2R,3R,5S)‐(−)‐2,6,6‐trimethyl­bicyclo­[3.1.1]heptan‐3‐amine]palladium(II), [PdCl₂(C₁₀H₁₉N)₂], and trans‐dichloro­bis[(1S,2S,3S,5R)‐(+)‐2,6,6‐trimethyl­bicyclo­[3.1.1]heptan‐3‐amine]palladium(II) hemihydrate, [PdCl₂(C₁₀H₁₉N)₂]·0.5H₂O, present different arrangements of the amine ligands coordinated to Pd^II, viz. antiperiplanar in the former case and (−)anticlinal in the latter. The hemihydrate is an inclusion compound, with a Pd coordination complex and disordered water mol­ecules residing on crystallographic twofold axes. The crystal structure for the hemihydrate includes a short Pd⋯Pd separation of 3.4133 (13) Å.     

Oxoanionic Noble Metal Compounds from Fuming Nitric Acid: The Palladium Examples Pd(NO3)2 and Pd(CH3SO3)2

The oxidation of elemental palladium at 100 °C in a mixture of fuming nitric acid and a pyridine‐SO₃ complex leads to the anhydrous nitrate Pd(NO₃)₂ (monoclinic, P2₁/n, Z=2, a=469.12(3) pm, b=593.89(3) pm, c=805.72(4) pm, β=105.989(3)°, V=215.79(2) ų). The Pd²⁺ ions are in square‐planar coordination with four monodentate nitrate groups which are connected to further palladium atoms, leading to a layer structure. The reaction of elemental palladium with a mixture of fuming nitric acid and methanesulfonic acid at 120 °C leads to single crystals of Pd(CH₃SO₃)₂ (monoclinic, P2₁/n, Z=2, a=480.44(1) pm, b=1085.53(3) pm, c=739.78(2) pm, β=102.785(1)°, V=376.254(17) ų). Also in this structure the Pd²⁺ ions are in square‐planar coordination with four monodentate anions; however, the connection to adjacent palladium atoms leads to a chain‐type structure. The thermal decomposition of the compounds has been investigated by means of DSC/TG measurements. Furthermore, IR and Raman spectra have been recorded, and an assignment of the observed vibrational frequencies has been carried out based on theoretical investigations.     

Structural Characterization of Some Coinage Metal(I) Thiosulfate Complexes, $\rm M^{1}_{a}M\rm ^{2}_{b}(X_{c}) (S_{2}O_{3})_{d}(\cdot eS)$ (M1 = Group 1 Cation,X = Univalent Anion,M2 = CuI,AgI, S = Solvent)

Building on previous single crystal X‐ray structure determinations for the group 1 salts of complex thiosulfate/univalent coinage metal anions previously defined for (NH₄)₉AgCl₂(S₂O₃)₄, NaAgS₂O₃·H₂O and Na₄[Cu(NH₃)₄][Cu(S₂O₃)₂]·NH₃, a wide variety of similar salts, of the form , M¹ = group 1 metal cation, M² = univalent coinage metal cation (Cu, Ag), (X = univalent anion), most previously known, but some not, have been isolated and subjected to similar determinations. These have defined further members of the isotypic, tetragonal series, for M¹ = NH₄, M² = Cu, Ag, X = NO₃, Cl, Br, I, together with the K/Cu/NO₃ complex, all containing the complex anion [M²(SSO₃)₄]^7? with M² in an environment of symmetry, Cu, Ag‐S typically ca. 2.37, 2.58Å, with quasi‐tetrahedral S‐M‐S angular environments. Further salts of the form , n = 1‐3, have also been defined: For n = 3, M² = Cu, M¹/x = K/2.25 or 1 5/6, NH₄/6, (and also for the (NH₄)₄Na/4H₂O·MeOH adduct) the arrays take the form with distorted trigonal planar CuS₃ coordination environments, Cu‐S distances being typically 2.21Å, S‐Cu‐S ranging between 105.31(4)–129.77(4)°; the silver counterparts take the form for M¹ = K, NH₄. For n = 2, adducts have only been defined for M² = Ag, the anions of the M¹ = Na, K adducts being dimeric and polymeric respectively: Na₆[(O₃SS)₂Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, K₃[Ag(μ‐SSO₃)₂]_(∞|∞)·H₂O; a polymeric copper(I) counterpart of the latter is found in Na₅Cu(NO₃)₂(S₂O₃)₂ ≡ 2NaNO₃·Na₃[Cu(μ‐SSO₃)₂]_(∞|∞). For n = 1, NaAgS₂O₃, the an‐ and mono‐ hydrates, exhibit a two‐dimensional polymeric complex anion in both forms but with different contributing motifs. (NH₄)₁₃Ag₃(S₂O₃)₈·2H₂O takes the form (NH₄)₁₃[{(O₃SS)₃Ag(μ‐SSO₃)}₂Ag], a linearly coordinated central silver atom linking a pair of peripheral [Ag(SSO₃)₄]^7? entities. In Na₆[(O₃SS)Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, the binuclear anions present as Ag₂S₄ sheets, the associated oxygen atoms being disposed to one side, thus sandwiching layers of sodium ions; the remarkable complex Na₅[Ag₃(S₂O₃)₄]_(∞|∞)·H₂O is a variant, in which one sodium atom is transformed into silver, linking the binuclear species into a one‐dimensional polymer. In (NH₄)₈[Cu₂(S₂O₃)₅]·2H₂O a binuclear anion of the form [(O₃SS)₂Cu(μ‐S.SO₃)Cu(SSO₃)₂]^8? is found; the complex (NH₄)₁₁Cu(S₂O₃)₆ is 2(NH₄)₂(S₂O₃)·(NH₄)₇[Cu(SSO₃)₄]. A novel new hydrate of sodium thiosulfate is described, 4Na₄S₂O₃·5H₂O, largely describable as sheets of the salt, shrouded in water molecules to either side, together with a redetermination of the structure of 3K₂S₂O₃·H₂O.     

Kristallstruktur und schwingungsspektrometrische Daten von cis-Na2[Pd(SO3)2en] · 4 H2O

Crystal Structure and Data from Vibrational Spectra of cis-Na₂[Pd(SO₃)₂en] · 4 H₂O The compound cis-Na₂[Pd(SO₃)₂en] · 4 H₂O (en = 1,2-diaminoethane) crystallizes in the orthorhombic space group Pnma with a = 623.7(2), = 1070.9(10), c = 1989.5(30) pm and Z = 4. In the [Pd(SO₃)₂en]^2? anions the trans-influence of the sulfite ligands manifests itself in long Pd? N bonds with short Pd? S distances. A set of Na⁺ ions is present in face-sharing octahedra Na(OH₂)₆⁺, forming rods [Na(OH₂)_6/2]⁺ parallel to [100]. A second set of Na⁺ ions is surrounded by two H₂O molecules and four O atoms from SO₃ ligands of two anions to form likewise octahedra with face-sharing, yielding rods [Na(OH₂)_2/2{(OSO₂)₂Pd en}_2/2]^? parallel to [100]. Comparatively low v(Pd? N)-frequencies reveal the trans-influence of the sulfite ligands also in the vibrational spectra.     

K2[Hg(SO3)2]·2.25H2O

The characteristic feature of the structure of the title compound, dipotassium bis(sulfito‐κS)mercurate(II) 2.25‐hydrate, is a layered arrangement parallel to (001) where each of the two independent [Hg(SO₃)₂]²⁻ anions are grouped into centrosymmetric pairs and are surrounded by two K⁺ cations to give the overall layer composition {K₂[Hg(SO₃)₂]₂}²⁻. The remaining cations and the uncoordinated water molecules are situated between these layers. Within the [Hg(SO₃)₂]²⁻ anions, the central Hg atoms are twofold coordinated by S atoms, with a mean Hg—S bond length of 2.384 (2) Å. The anions are slightly bent [174.26 (3) and 176.99 (3)°] due to intermolecular O...Hg interactions greater than 2.8 Å. All coordination polyhedra around the K⁺ cations are considerably distorted, with coordination numbers ranging from six to nine. Although the H atoms of the five water molecules (one with symmetry 2) could not be located, O...O separations between 2.80 and 2.95 Å suggest a system of medium to weak O—H...O hydrogen bonds which help to consolidate the structural set‐up. Differences and similarities between the bis(sulfito‐κS)mercurate(II) anions in the title compound and those in the related salts (NH₄)₂[Hg(SO₃)₂] and Na₂[Hg(SO₃)₂]·H₂O are discussed.