(Hg2)Hg(OH)2(ClO4)2: Das erste gemischtvalente Quecksilberperchlorat

(Hg₂)Hg(OH)₂(ClO₄)₂: The First Mixed Valent Mercury Perchlorate Colorless single crystals of (Hg₂)Hg(OH)₂(ClO₄)₂ (C2/c, Z = 4, a = 1847.7(5), b = 490.8(1), c = 1086.2(3) pm, β = 93.80(2)°, R_all = 0.0610) were obtained as a side product during the dehydration of Hg₂(ClO₄)₂ · 2H₂O. The crystal structure consists of infinite zig‐zag chains {_∞¹[(Hg₂)_1/2(OH)Hg_1/2]⁺}₂ which are separated by the ClO₄^— ions.     

Die Reaktionen von M[BF4] (M = Li,K) und (C2H5)2O·BF3 mit (CH3)3SiCN. Bildung von M[BFx>(CN)4—x] (M = Li,K; x = 1, 2) und (CH3)3SiNCBFx(CN)3—x, (x = 0, 1)

The Reactions of M[BF₄] (M = Li, K) and (C₂H₅)₂O·BF₃ with (CH₃)₃SiCN. Formation of M[BF_x(CN)_4—x] (M = Li, K; x = 1, 2) and (CH₃)₃SiNCBF_x(CN)_3—x, (x = 0, 1) The reaction of M[BF₄] (M = Li, K) with (CH₃)₃SiCN leads selectively, depending on the reaction time and temperature, to the mixed cyanofluoroborates M[BF_x(CN)_4—x] (x = 1, 2; M = Li, K). By using (C₂H₅)₂O·BF₃ the synthesis yields the compounds (CH₃)₃SiNCBF_x(CN)_3—x x = 0, 1. The products are characterized by vibrational and NMR‐spectroscopy, as well as by X‐ray diffraction of single‐crystals: Li[BF₂(CN)₂]·2Me₃SiCN Cmc2₁, a = 24.0851(5), b = 12.8829(3), c = 18.9139(5) Å V = 5868.7(2) ų, Z = 12, R₁ = 4.7%; K[BF₂(CN)₂] P4₁2₁2, a = 13.1596(3), c = 38.4183(8) Å, V = 6653.1(3) ų, Z = 48, R₁ = 2.5%; K[BF(CN)₃] P1¯, a = 6.519(1), b = 7.319(1), c = 7.633(2) Å, α = 68.02(3), β = 74.70(3), γ = 89.09(3)°, V = 324.3(1) ų, Z = 2, R₁ = 3.6%; Me₃SiNCBF(CN)₂ Pbca, a = 9.1838(6), b = 13.3094(8), c = 16.840(1) Å, V = 2058.4(2) ų, Z = 8, R₁ = 4.4%     

Kristallstrukturen von Säurehydraten und Oxoniumsalzen. XX. Die Oxoniumtetrafluoroborate H3OBF4, [H5O2]BF4 und [H(CH3OH)2]BF4

Crystal Structures of Acid Hydrates and Oxonium Salts. XX. Oxonium Tetrafluoroborates H₃OBF₄, [H₅O₂]BF₄, and [H(CH₃OH)₂]BF₄ The crystal structures of three oxonium tetrafluoroborates were determined. H₃OBF₄, oxonium tetrafluoroborate proper, is triclinic with space group P1 , Z = 2 and the unit cell dimensions a = 4.758, b = 6.047, c = 6.352 Å and α = 80.40, β = 79.48, γ = 88.25° at ?26°C. Cations H₃O⁺ and anions BF₄^? are linked by hydrogen bonds O? H…?F into ribbons of condensed rings. In [H₅O₂]BF₄ (diaquohydrogen tetrafluoroborate, monoclinic, P2₁/c, Z = 4, a = 6.584, b = 9.725, c = 7.084 Å, β = 95.15° at ?100°C) the hydrogen bond in the cation H₅O₂⁺ is 2.412 Å short, asymmetric and approximately centered and the linking of cations and anions three-dimensional. In [H(CH₃OH)₂]BF₄ (Bis(methanol)hydrogen tetrafluoroborate, monoclinic, P2₁/c, Z = 4, a = 5.197, b = 14.458, c = 9.318 Å, β = 94.61° at ?50°C) the cation [H(CH₃OH)₂]⁺ is characterized for the first time in a crystal structure with an again very short (2.394 Å), asymmetric and effectively centered hydrogen bond. By further hydrogen bonds cations and anions form only dimers of the formula unit of centrosymmetric cyclic structure.     

Aufbau und Abbau von (NH4)[BF4] und H3N‐BF3

Production and Decomposition of (NH₄)[BF₄] and H₃N‐BF₃ (NH₄)[BF₄] is produced as single crystals during the reaction of elemental boron and NH₄HF₂ (B : NH₄HF₂ = 1 : 2) and NH₄F (B : NH₄F = 1 : 4), respectively, in sealed copper ampoules at 300 °C. The crystal structure (baryte type, orthorhombic, Pnma, Z = 4) was redetermined at ambient temperature (a = 909.73(18), b = 569.77(10), c = 729.47(11) pm, R_all = 0.0361) and at 140 K (a = 887.3(2), b = 574.59(12), c = 717.10(12) pm, R_all = 0.0321). Isolated (NH₄)⁺ and [BF₄]^— tetrahedra are the important building units. The thermal behaviour of (NH₄)[BF₄] was investigated under inert (Ar, N₂) and reactive conditions (NH₃) with the aid of DTA/TG and DSC measurements and with in‐situ X‐ray powder diffraction as well. Finally, (NH₄)[BF₄] is decomposed yielding NH₃ and BF₃, BN is not produced under the current conditions. Colourless single crystals of H₃N‐BF₃ were prepared directly from the components NH₃ and BF₃. The crystal structure was determined anew at 293 and 170 K (orthorhombic, Pbca, Z = 8, a = 815.12(10), b = 805.91(14), c = 929.03(12) pm, R_all = 0.0367; a = 807.26(13), b = 800.48(10), c = 924.31(11) pm, R_all = 0.0292, T = 170 K). The crystal structure contains isolated molecules H₃N‐BF₃ in staggered conformation with a B‐N distance of 158 pm. The thermal behaviour of H₃N‐BF₃ was studied likewise.     

Polysulfonylamine. XXXVII. Darstellung von Quecksilberdimesylamiden. Kristall- und Molekülstrukturen von Hg[N(SO2CH3)2]2, Hg[{N(SO2CH3)2}2(DMSO)2] und Hg[{N(SO2CH3)2}2(HMPA)]

Polysulfonyl Amines. XXXVII. Preparation of Mercury Dimesylamides. Crystal and Molecular Structures of Hg[N(SO₂CH₃)₂]₂, Hg[{N(SO₂CH₃)₂}₂(DMSO)₂], and Hg[{N(SO₂CH₃)₂}₂(HMPA)] Hg[N(SO₂CH₃)₂]₂ ( 1 ) and Hg₂[N(SO₂CH₃)₂]₂ ( 2 a ) are formed as colourless, sparingly soluble precipitates when solutions of Hg(NO₃)₂ or Hg₂(NO₃)₂ in dilute nitric acid are added to an aqueous HN(SO₂CH₃)₂ solution. By a similar reaction, Hg₂[N(SO₂C₆H₄ ? Cl? 4)₂]₂ is obtained. 1 forms isolable complexes of composition Hg[N(SO₂CH₃)₂]₂ · 2 L with L = dimethyl sulfoxide (complex 3 a ), acetonitrile, dimethyl formamide, pyridine or 1,10-phenanthroline and a (1/1) complex Hg[N(SO₂CH₃)₂]₂ · HMPA ( 4 ) with hexamethyl phosphoramide. Attempted complexation of 2 a with some of these ligands induced formation of Hg⁰ and the corresponding Hg^II complexes. Crystallographic data (at -95°C) are for 1: space group 14₁/a, a = 990.7(2), c = 2897.7(8) pm, V = 2.844 nm³, Z = 8, D_x = 2.545Mgm^?3; for 4a: space group P1 , a = 767.8(2), b = 859.2(2), c = 925.2(2)pm α = 68.44(2), β = 86.68(2), γ = 76.24(2)°, V = 0.551nm³, Z = 1, D_x = 2.113 Mgm^?3; for 4: space group P2₁/c, a = 1041.3(3), b = 1545.4(3), c = 1542.5(3) pm, β = 100.30(2)°, V = 2.474nm³, Z = 4, D_x = 1.944Mgm³. The three compounds form molecular crystals. The molecular structures contain a linear or approximately linear, covalent NHgN moiety; the Hg? N distances and N? Hg? N angles are 206.7(4) pm and 176.3(2)° for 1, 207.2(2) pm and 180.0° for 3a, 205.7(4)/206.7(4) pm and 170.5(1)° for 4. In the complexes 3a and 4, the 0-ligands are bonded to the Hg atoms perpendicularly to the N? Hg? N axes, leading in 3a to a square-planar trans-(N₂O₂) coordination with Hg? 0 261.2(2) pm and N? Hg? O 92.3(1)/87.7(1)°, in 4 to a slightly distorted T-shaped (N₂O) geometry with Hg? 0 246.2(4)pm and N? Hg? 0 96.7(1)/92.0(1)°. In all three structures, the primary coordination is extended to a severely distorted (N₂O₄) hexacoordination by the appropriate number of secondary, inter- and/or intramolecular Hg…?0 inter-actions (0 atoms from sulfonyl groups, Hg…?O distances in the range 280—300pm). The intramolecular Hg…?O interactions give rise to nearly planar four-membered [HgNSO] rings. The molecule of 1 has a two-fold axis through the bisector of the N? Hg? N angle, the molecule of 3a an inversion center at the Hg atom. The molecule of 4 has no symmetry.     

Carbyne-fluoro complexes of rhenium. Single-pot synthesis of trans-[ReF(CCH2R)-(Ph2PCH2CH2PPh2)2][BF4]

Treatment of a THF solution of trans-[ReCl(N₂)(dppe)₂] (dppe = Ph₂PCH₂CH₂PPh₂) with a 1-alkyne HCCR (R =^tBu, CO₂Me, CO₂Et, or C₆H₄Me-4), in the presence of Tl[BF₄]/[NH₄][BF₄], under sunlight, affords the corresponding carbyne-fluoro complexes trans-[ReF(CCH₂R)(dppe)₂][BF₄] in an unprecedented single-pot synthesis. Further reaction with [BU₄N]OH leads to the vinylidenefluoro compounds trans-[ReF(=C=CHR)(dppe)₂] (R = CO₂Me, CO₂Et, or C₆H₄Me-4).     

Demasking reactions of potassium hydroxotrifluoroborate with lanthanum(III) complexes of polyaminopolycarboxylic acids: Part 1. Equilibrium constants for the reactions with EDTA and NTA complexes

Equilibrium constants for the demasking reactions of potassium hydroxotrifluoroborate. (KBF₃OH) toward La(III) complexes of EDTA and NTA have been estimated by means of ¹H-n.m.r- measurement at 35°C. For the constants defined as K^BF_LaLm = [L]^m[La(BF₃OH)_n]/[LaL_m][BF₃OH]_n, the results were: for EDTA (m = 1,n = $\text{1}\text{3}$) K^BF_LaL = 10^2.7, and for NTA (m = 2, n = $\text{1}\text{3}$) K^BF_LaL2 = 1026. These values are much larger than the equilibrium constants for the well known demasking reaction of fluoride ion toward La(III) complexes of EDTA and NTA, which are —12.43 and —14.92, respectively.     

Synthesis and Structure of [Hg{OP(O)CF3(OH)}2(PMe3)3], a Distorted Trigonal Bipyramidal Complex Connected by Hydrogen Bridges to Polymeric Chains

The hydrolysis of [Hg{P(CF₃)₂}₂(PMe₃)₂] yields colourless crystals of [Hg{OP(O)CF₃(OH)}₂(PMe₃)₃]. The proposed multistep reaction proceeds via primary hydrolysis of the starting material giving HgO and HP(CF₃)₂. The latter is directly oxidized by HgO to (CF₃)₂P(O)OH. The bis(trifluoromethyl)phosphinic acid hydrolyses to CF₃P(O)(OH)₂ which reacts with [Hg{P(CF₃)₂}₂(PMe₃)₂] in the presence of PMe₃ to the title compound. The crystal structure was determined by X‐ray single‐crystal analysis (triclinic; P1¯; a = 860.7(1), b = 1007.6(2), c = 1625.0(3) pm; α = 96.09(2), β = 101.09(2), γ = 107.79(2)°; Z = 2) and exhibits distorted trigonal bipyramidal mercury complexes which are connected to polymeric chains. The acidic units, {OP(O)CF₃(OH)}^—, are connected via intermolecular hydrogen bridges, forming two individual centrosymmetric eight membered rings with asymmetric hydrogen bridges with O—O distances of 249.4(8) and 250.8(8) pm.     

Synthesis,stability and reactivity of cationic carbonyl complexes of rhodium(I)

Summary Trans-[RhCl(CO)L₂] (L = PPh₃, AsPh₃ or PCy₃) react with AgBF₄ in CH₂Cl₂ to give the novel species [Rh-(CO)L₂]⁺ [BF₄]^–.nCH₂Cl₂ (n = 1/2 or 1 1/2) (1–3), which we believe to be stabilised by weak solvent interaction. The corresponding stibine compound cannot be isolated by the same process, instead [Rh(CO)₂(SbPh₃)₃]⁺ [BF₄]^– (7) is formed when the reaction is carried out in the presence of CO. When reactions designed to prepare [Rh(CO)L₂]⁺ [BF₄]^– are performed in the presence of CO, or [Rh(CO)L₂]⁺ [BF₄]^– complexes are reacted with CO, [Rh(CO)₂L₂]⁺ [BF₄]^– (L = PPh₃, AsPh₃ or PCy₃) (4–6) are formed. If Me₂CO is used as solvent in the preparation of [Rh(CO)L₂]⁺ [BF₄]^– (L = PPh₃ or AsPh₃), then the products are the four-coordinate [Rh(CO)L₂-(Me₂CO)]⁺ [BF₄]^– (8,9) species. The complexes have been characterised by i.r., ³¹P and ¹H n.m.r. spectroscopy and elemental analyses.     

Benzeneselenolates of Mercury(II). Crystal and Molecular Structures of [Hg(SePh)2] and (Bu4N)[Hg(SePh)3]

The reaction of dibenzenediselenide, (SePh)₂, with mercury in refluxing xylene gives bis(benzeneselenolato)mercury(II), [Hg(SePh)₂], in a good yield. (ⁿBu₄N)[Hg(SePh)₃] is obtained by the reaction of [Hg(SePh)₂] with a solution of [SePh]^– and (ⁿBu₄N)Br in ethanol. The solid state structures of both compounds have been determined by X-ray diffraction. The mercury atom in [Hg(SePh)₂] (space group C2, a = 7.428(2), b = 5.670(1), c = 14.796(4) Å, β = 103.60(1)°) is linearly co-ordinated by two selenium atoms (Hg–Se = 2.471(2) Å, Se–Hg–Se = 178.0(3)°). Additional weak interactions between the metal and selenium atoms of neighbouring molecules (Hg…Se = 3.4–3.6 Å) associate the [Hg(SePh)₂] units to layers. The crystal structure of (ⁿBu₄N)[Hg(SePh)₃] (space group P2₁/c, a = 9.741(1), b = 17.334(1), c = 21.785(1) Å, β = 95.27(5)°) consists of discrete complex anions and (ⁿBu₄N)⁺ counter ions. The coordination geometry of mercury is distorted trigonal-planar with Hg–Se distances ranging between 2.5 and 2.6 Å.     

(C2H10N2)[BPO4F2] — Structural Relations between [BPO4F2]2— and [Si2O6]4—

(C₂H₁₀N₂)[BPO₄F₂] — Strukturbeziehungen zwischen [BPO₄F₂]^2— und [Si₂O₆]^4— Colourless crystals of (C₂H₁₀N₂)[BPO₄F₂] were prepared from mixture of ethylendiamine, H₃BO₃, BF₃ · C₂H₅NH₂, H₃PO₄ and HCl under mild hydrothermal conditions (220 °C). The crystal structure was determined by single crystal methods (triclinic, P1¯ (no. 2), a = 451.85(5) pm, b = 710.20(8) pm, c = 1210.2(2) pm, α = 86.08(1)°, β = 88.52(2)°, γ = 71.74(1)°, Z = 2) and contains infinite tetrahedral zweier‐single‐chains {[BPO₄F₂]^2—} which are isoelectronic (48e^—) with the polyanions {[Si₂O₆]^4—} of the pyroxene family.     

Crystal Structure and Thermal Behaviour of the Mixed‐Valent Basic Mercury Nitrate HgI2(OH)(NO3)·HgIIO

Single crystals of the hitherto unknown compound Hg₂(OH)(NO₃)·HgO were obtained unintentionally during hydrothermal phase formation experiments in the system Ag—Hg— As—O. Hg₂(OH)(NO₃)·HgO (orthorhombic, Pbca, Z = 8, a = 6.4352(8), b = 11.3609(14), c = 15.958(2) Å, 1693 structure factors, 83 parameters, R1[F² > 2σ(F²)] = 0.0431) adopts a new structure type and is composed of two types of mercury‐oxygen zig‐zag‐chains running perpendicular to each other and of intermediate nitrate groups. One type of chains runs parallel [010] and consists of (Hg—Hg—OH) units with a typical Hg—Hg distance of 2.5143(10) Å for the mercury dumbbell, whereas the other type of chains runs parallel [100] and is made up of (O—Hg—O) units with short Hg—O distances of about 2.02Å. Both types of chains are concatenated by a common O atom with a slightly longer Hg—O distance of 2.25Å. The three‐dimensional assembly is completed by nitrate groups whose O atoms show Hg—O distances > 2.80Å. Weak hydrogen bonding between the OH group and one oxygen atom belonging to the nitrate group stabilizes this arrangement. Hg₂(OH)(NO₃)·HgO decomposes above 200 °C to HgO.     

Synthese und Kristallstruktur von [Cr(NH3)6][Cr(NH3)2F4][BF4]2

Synthesis and Crystal Structure of [Cr(NH₃)₆][Cr(NH₃)₂F₄][BF₄]₂ The action of ammonium fluoride on a mixture of boron and chromium in a sealed Monel ampoule at 300 °C yields single crystals of [Cr(NH₃)₆][Cr(NH₃)₂F₄][BF₄]₂. The crystal structure (tetragonal, P4/mbm, Z = 2, a = 1056.0(1), c = 781.7(1) pm; R₁ = 0.0414; wR₂ = 0.1087 for 411 reflections with I₀ > 2σ(I)) contains [Cr(NH₃)₆]³⁺ and [Cr(NH₃)₂F₄]^– octahedra and twice as many [BF₄]^– tetrahedra that are arranged in a quadrupled super‐structure of the CsCl‐type of structure.     

SYNTHESIS OF A DINUCLEAR YLID COMPLEX DERIVED FROM P(OPh)3: CRYSTAL STRUCTURES OF [Cp2Fe2(CO)2(μ-CO) (μ-CHP(OPh)3)+][BF4 −] AND [Cp2Fe2(CO)2 (μ-CO)(μ-CHPPh3)+][BF4 −]

Abstract

[Cp₂Fe₂(CO)₂(μ-CO)(μ-CHP(OPh)₃)⁺][BF^? ₄] crystallizes in the centrosymmetric monoclinic space group P2₁/n with a = 12.553(7) Å, b = 16.572(11) Å, c = 15.112(8) Å, β = 100.00(4)°, V = 3096(3) ų and D(calcd.) = 1.579 g/cm³ for Z = 4. The structure was refined to R(F) = 5.83% for 1972 reflections above 4σ(F). The cation contains two CpFe(CO) fragments linked via an iron—iron bond (Fe(1)—Fe(2) = 2.544(3)Å), a bridging carbonyl ligand (Fe(1)—C(4) = 1.918(1) Å, Fe(2)—C(4) = 1.946(12)Å) and a bridging CHP(OPh)₃ ligand (Fe(1)—C(1) = 1.980(9)Å, Fe(2)—C(1) = 1.989(8)Å). Distances within the μ-CHP(OPh)₃ moiety include a rather short carbon—phosphorus bond [C(1)—P(1) = 1.680(10)Å] and P—O bond lengths of 1.550(7)–1.579(6)Å. The crystal is stabilized by a network of F…H—C interactions involving the BF^? ₄ anion.

[Cp₂Fe₂(CO)₂(μ-CO)(μ-CHPPh₃)⁺][BF^? ₄], which differs from the previous compound only in having a μ-CHPPh₃ (rather than μ-CHP(OPh)₃) ligand, crystallizes in the centrosymmetric monoclinic space group P2₁/c with a = 11.248(5)Å, b = 13.855(5)Å, c = 18.920(7)Å, β = 96.25(3)°, V = 2931(2)ų and D(calcd.) = 1.559 g/cm³ for Z = 4. This structure was refined to R(F) = 4.66% for 1985 reflections above 4σ(F). Bond lengths within the dinuclear cation here include Fe(1)-Fe(2) = 2.529(2)Å, Fe(1)—C(3) = 1.904(9) Å and Fe(2)—C(3) = 1.911(8) Å (for the bridging CO ligand) and Fe(1)—C(1P) = 1.995(6) Å and Fe(2)—C(1P) = 1.981(7) Å (for the bridging CHPPh₃ ligand). Distances within the μ-CHPPh₃ ligand include a longer carbon—phosphorus bond [C(1P)—P(1) = 1.768(6)Å] and P(1)—C(phenyl) = 1.797(7)–1.815(8) Å.     

Zwei Mercuri‐Ammin‐Komplexe: [Hg(NH3)2][HgCl3]2 und [Hg(NH3)4](ClO4)2

Two Mercuric Ammoniates: [Hg(NH₃)₂][HgCl₃]₂ and [Hg(NH₃)₄](ClO₄)₂ [Hg(NH₃)₂][HgCl₃]₂ ( 1 ) is obtained by saturating an equimolar solution of HgCl₂ and NH₄Cl with Hg(NH₂)Cl at 75 °C. 1 crystallizes in the orthorhombic space group Pmna with a = 591.9(1) pm, b = 800.3(1) pm, c = 1243.3(4) pm, Z = 2. The structure consists of linear cations [Hg(NH₃)₂]²⁺ and T‐shaped anions [HgCl₃]^—. The coordination sphere of mercury is ?effectively”? completed to compressed hexagonal bipyramids and distorted octahedra, respectively. Single crystals of [Hg(NH₃)₄](ClO₄)₂ ( 2 ) are obtained by passing gaseous ammonia through a solution of mercuric perchlorate, while the solution was cooled to temperatures below 10 °C. 2 crystallizes in the monoclinic space group P2₁/c with a = 791.52(9) pm, b = 1084.3(2) pm, c = 1566.4(2) pm, β = 120.352(1)°, Z = 4. The structure consists of compressed [Hg(NH₃)₄]²⁺ tetrahedra and perchlorate anions. The packing of the heavy atoms Hg and Cl is analogous to the baddeleyite (α‐ZrO₂) type of structure.     

Alkalimetall‐Stannid‐Silicate und ‐Germanate: ‘Doppelsalze’ mit dem Zintl‐Anion [Sn4]4—

Alkaline Metal Stannide‐Silicates and ‐Germanates: ‘Double Salts’ with the Zintl Anion [Sn₄]^4— The crystal structures of the tetrelid tetrelates A₁₂[Sn₄]₂[GeO₄] (A = Rb/Cs: monoclinic, P2₁/c, a = 1289.1(2) / 1331.72(7), b = 2310.1(4)/ 2393.6(1), c = 1312.6(2)/ 1349.21(7) pm, β = 119.007(3)/ 118.681(1)°, Z = 4, R1 = 0.1049/0.0803) and Cs₂₀[Sn₄]₂[SiO₄]₃ (monoclinic, Cc, a = 2331.9(1), b = 1340.1(2), c = 1838.9(2) pm, β= 102.61(3)°, R1 = 0.0763) contain the Zintl anions [Sn₄]^4— and isolated oxotetrelate ions [MO₄]^4— (M = Si, Ge). The high temperature form of CsSn crystallizes with the KGe type (cubic, P4¯3n, a = 1444.7(1) pm, R1 = 0.0395).     

Zur Struktur der basischen Diquecksilber(I)-nitrate. II. Kristallstruktur des Hg10(OH)4(NO3)6

Crystal Structure of the Basic Dimercury(I) Nitrates. II. Crystal Structure of Hg₁₀(OH)₄(NO₃)₆ . The crystal structure of Hg₁₀(OH)₄(NO₃)₆ has been determined from single crystal x-ray diffraction data. The unit cell is triclinic, space group P1 , a = 999.4(5), b = 909.9(5), c = 765.9(2) pm, α = 85.98(4), β = 78.70(3), γ = 109.83(5)°; Z = 1, R = 6.2%, R_w = 8.2%. Finite cationic chains [(Hg₂)₅(OH)₄(NO₃)₂]⁴⁺ are joined together by weak van der Waals-type interactions between neighbouring Hg and O atoms, thus forming ribbons running along [100]. The coordination sphere of the Hg atoms is completed by further nitrate ions, which lead to the formation of a loose framework. Thereby the metal atoms are not surrounded by simple coordination polyhedra.     

Synthese und Kristallstruktur von [Na(12-Krone-4)2]2[Hg(Se4)2] · 1,5 DMF

Synthesis and Crystal Structure of [Na(12-Crown-4)₂]₂[Hg(Se₄)₂] · 1.5 DMF . The title compound has been prepared by the reaction of Na₂Se₄ with mercury acetate in DMF solution in the presence of 15-crown-5, forming dark red crystal needles. [Na(12-crown-4)₂]₂[Hg(Se₄)₂] · 1.5 DMF crystallizes in the space group C2/c with eight formula units per unit cell. The structure was determined with 3 824 observed unique reflections, R = 0.085. Lattice dimensions at - 70°C: a = 2 884(2), b = 1 407.7(7), c = 2 843(2) pm, β = 93.93(5)°. The structure consists of [Na(12-crown-4)₂]⁺ ions with a sandwichlike coordination of the crown ether molecules, and of [Hg(Se₄)₂]^2? ions, in which the mercury atom is coordinated by two tetraselenido ions in a chelating fashion. The [Hg(Se₄)₂]^2? ions are arranged to infinite chains via Se…?Se contacts.     

Structural Transformations and Spin-Crossover in [FeL2]2+ Salts (L=4-{tert-Butylsulfanyl}-2,6-di{pyrazol-1-yl}pyridine): The Influence of Bulky Ligand Substituents

4-(tert-Butylsulfanyl)-2,6-di(pyrazol-1-yl)pyridine (L) was obtained in low yield from a one-pot reaction of 2,4,6-trifluoropyridine with 2-methylpropane-2-thiolate and sodium pyrazolate in a 1:1:2 ratio. The materials [FeL₂][BF₄]₂⋅solv ( 1[BF₄]₂ ⋅solv) and [FeL₂][ClO₄]₂⋅solv ( 1[ClO₄]₂ ⋅solv; solv=MeNO₂, MeCN or Me₂CO) exhibit a variety of structures and spin-state behaviors including thermal spin-crossover (SCO). Solvent loss on heating 1[BF₄]₂ ⋅x MeNO₂ (x≈2.3) occurs in two steps. The intermediate phase exhibits hysteretic SCO around 250 K, involving a “reverse-SCO” step in its warming cycle at a scan rate of 5 K min⁻¹. The reverse-SCO is not observed in a slower 1 K min⁻¹ measurement, however, confirming its kinetic nature. The final product [FeL₂][BF₄]₂⋅0.75 MeNO₂ was crystallographically characterized, and shows abrupt but incomplete SCO at 172 K which correlates with disorder of an L ligand. The asymmetric unit of 1[BF₄]₂ ⋅y Me₂CO (y≈1.6) contains five unique complex molecules, four of which undergo gradual SCO in at least two discrete steps. Low-spin 1[ClO₄]₂ ⋅0.5 Me₂CO is not isostructural with its BF₄⁻ congener, and undergoes single-crystal-to-single-crystal solvent loss with a tripling of the crystallographic unit cell volume, while retaining the P space group. Three other solvate salts undergo gradual thermal SCO. Two of these are isomorphous at room temperature, but transform to different low-temperature phases when the materials are fully low-spin.     

Characteristic structural features of cyclopentadienyl derivatives of post-transition metals : II. Synthesis and structure of tris(triphenylphosphinegold)tetraphenylcyclopentadiene tetrafluoroborate

The trinuclear cationic complex [Ph₄C₅(AuPPh₃)₃⁺[BF₄]^- (I) obtained by interaction of C₅HPh₄AuPPh₃ or Ph₄C₅(AuPPh₃)₂ with [AuPPh₃⁺[BF₄]^- in THF was studied by X-ray diffraction. In the presence of benzene, triclinic crystals of the solvate [Ph₄C₅(AuPPh₃)₃]⁺[BF₄]^-· 2 C₆H₆ are formed, a = 12.845(6), b = 16.042(8), c = 22.642(11) Å, α = 86.62(4), β = 77.51(4), γ = 76.05(4)°, space group P$\text{1}$, Z = 2, 9494 reflections with I > 2σ (λ(Mo-K_α), θ/2θ scan, 2θ < 46°), with absorption correction R = 0.054. The complex represents a diaurated cation of tetraphenylcyclopentadienyl(triphenylphosphine)gold, containing a triangular Au₂C fragment (AuAu 2.820(1) Å) which is bonded to the third Au atom (AuAu 3.021(1) Å), coordinated to the cyclopentadienyl ligand by a bond intermediate between η¹(σ) and η³ (AuC 2.21(2), 2.60(2) and 2.71(2) Å).