Syntheses and crystal structures of [Mg(HF)2](SbF6)2 and [Ca(HF)2](SbF6)2: new examples of HF acting as a ligand to metal centres

[Mg(HF)₂](SbF₆)₂ and [Ca(HF)₂](SbF₆)₂ monocrystals were grown from the corresponding hexafluoroantimonates(V) dissolved in anhydrous hydrogen fluoride. [Mg(HF)₂](SbF₆)₂ crystallizes in the space group Pnma (no. 62) with a=1249.1(4) pm, b=1230.2(4) pm, c=699.1(2) pm, V=1.0742(6) nm³, Z=4. Magnesium is octahedrally coordinated by six fluorine atoms from which two belong to two HF molecules. The structure can be represented by alternating rows of magnesium and antimony atoms running parallel to the c-axis. Magnesium atoms are connected by cis bridging Sb(2)F₆ units along the a-axis and by trans bridging Sb(1)F₆ units along the b-axis. In this way a three-dimensional network is formed.[Ca(HF)₂](SbF₆)₂ crystallizes in the space group P2₁/n (no. 14) with a=935.2(3) pm, b=1088.7(3) pm, c=1104.8(3) pm, β=106.697(5)°, V=1.0774(5) nm³, Z=4. The coordination sphere around the calcium atom consists of eight fluorine atoms which define the vertices of an Archimedean antiprism. The two HF molecules directly coordinate the calcium atom and their fluorine atoms are placed in the corners of different square faces of the Archimedean antiprism. The Ca-F(HF) distances are shorter than the Ca-F(Sb) distances. The Sb(1)F₆ and Sb(2)F₆ groups have four equatorial bridging fluorine atoms, while the Sb(3)F₆ groups have only two bridging trans F ligands. The Ca atoms in the [−1,0,1] plane are connected by equatorial F ligands of Sb(1)F₆ and Sb(2)F₆ units, forming a [Ca(SbF₆)⁺]_n layer. These layers are connected by trans bridging Sb(3)F₆ groups. HF molecules occupy the space between these layers and additionally contribute to the connection between the layers by hydrogen bonding.     

Alkaline earth metal poly(hydrogen fluorides) hexafluoroarsenates(V) and hexafluorophosphate(V): M2(H2F3)(HF2)2(AF6) (M = Ca, A = As; M = Sr, A = As, P)

New compounds of the type M₂(H₂F₃)(HF₂)₂(AF₆) with M = Ca, A = As and M = Sr, A = As, P) were isolated. Ca₂(H₂F₃)(HF₂)₂(AsF₆) was prepared from Ca(AsF₆)₂ with repeated additions of neutral anhydrous hydrogen fluoride (aHF). It crystallizes in a space group P4₃22 with a = 714.67(10) pm, c = 1754.8(3) pm, V = 0.8963(2) nm³ and Z = 4. Sr₂(H₂F₃)(HF₂)₂(AsF₆) was prepared at room temperature by dissolving SrF₂ in aHF acidified with AsF₅ in mole ratio SrF₂:AsF₅ = 2:1. It crystallizes in a space group P4₃22 with a = 746.00(12) pm, c = 1805.1(5) pm, V = 1.0046(4) nm³ and Z = 4. Sr₂(H₂F₃)(HF₂)₂(PF₆) was prepared from Sr(XeF₂)_n(PF₆)₂ in neutral aHF. It crystallizes in a space group P4₁22 with a = 737.0(3) pm, c = 1793.7(14) pm, V = 0.9744(9) nm³ and Z = 4. The compounds M₂(H₂F₃)(HF₂)₂(AF₆) gradually lose HF at room temperature in a dynamic vacuum or during being powdered for recording IR spectra or X-ray powder ray diffraction patterns. All compounds are isotypical with coordination of nine fluorine atoms around a metal center forming a distorted Archimedian antiprism with one face capped. This is the first example of the compounds in which H₂F₃⁻ and HF₂⁻ anions simultaneously bridge metal centers forming close packed three-dimensional network of polymeric compounds with low solubility in aHF. The HF₂⁻ anions are asymmetric with usual F?F distances of 227.3-228.5 pm. Vibrational frequency (ν₁) of HF₂⁻ is close to that in NaHF₂. The anion H₂F₃⁻ exhibits unusually small F?F?F angle of 95.1°-97.6° most probably as a consequence of close packed structure.     

Copper(I) hexafluoroantimonate - an example of a compound with Cu in a solely fluorine environment

Yellow-orange single crystals of CuSbF₆, were prepared by reacting Cu wire (∼10 mmol) with SbF₅ (∼3 mmol) in liquid anhydrous hydrogen fluoride (aHF) and by reduction of Cu(SbF₆)₂ with Cu metal in aHF. CuSbF₆ crystallizes rhombohedral at 296 K with the LiSbF₆ structure type, with a = 530.4(4) pm, c = 1453(1) pm and Z = 3, space group R (no. 148). The structure is dominated by isolated layers of regular [SbF₆]⁻ octahedra and Cu⁺ cations.An attempt to prepare CuF by reaction between CuSbF₆ and CsF in aHF at ∼190 K failed. Instead of CuF, a mixture of Cu and CuF₂ was obtained.     

Coordination compounds with XeF2, AsF3 and HF as ligands to metal ions: a review of reaction systematics, Raman spectra and metal, fluoro-ligand polyhedra

The reactions between Ln(AsF₆)₃ (Ln: lanthanide) and excess of XeF₂ in anhydrous HF (aHF) as a solvent yield coordination compounds [Ln(XeF₂)₃](AsF₆)₃ or LnF₃ together with Xe₂F₃AsF₆ or mixtures of all mentioned products depending on the fluorobasicity of XeF₂ and LnF₃ along the series. XeF₂ in a basic aHF is able to oxidize Pr³⁺ to Pr⁴⁺ besides Ce³⁺ to Ce⁴⁺ and Tb³⁺ to Tb⁴⁺. The tetrafluorides obtained are weaker fluorobases as XeF₂ and are immediately exchanged with XeF₂ yielding Xe₂F₃AsF₆ and LnF₄. The analogous reaction between Ln(BiF₆)₃ and XeF₂ in aHF yields [Ln(XeF₂)₃](BiF₆)₃, Ln: La, Nd. Raman spectra of the compounds [Ln(XeF₂)_n](AF₆)₃ (A: As, Bi) show that no XeF⁺ salts are formed. The interaction of XeF₂ with metal ion is covalent over the fluorine bridge. Analogous reactions of Ln(AsF₆)₃ with AsF₃ in aHF yield [Ln(AsF₃)₃](AsF₆)₃ which are stable in a dynamic vacuum at temperatures lower than 233 K. In reactions between M(AF₆)₂ (M: alkaline earth metal and Pb, A: As, Sb) and XeF₂ in aHF as a solvent, compounds of the type [M(XeF₂)_n](AF₆)₂ were synthesized. Analogous reactions with AsF₃ yield coordination compounds of the type [M(AsF₃)_n](AsF₆)₂. During the preparation of M^x(AsF₆)_x (M: metal in oxidation state x+) by the reaction between metal fluoride and excess of AsF₅ in aHF it was found that HF could also act as a ligand to the metal ions (e.g. Ca(HF)(AsF₆)₂).     

Group 12 metal aryl selenolates. Crystal and molecular structure of [2-(Et2NCH2)C6H4]2Se2 and [2-(Me2NCH2)C6H4Se]2M (M = Zn, Cd)

Diorganodiselenide [2-(Et₂NCH₂)C₆H₄]₂Se₂ (1) was obtained by hydrolysis/oxidation of the corresponding [2-(Et₂NCH₂)C₆H₄]SeLi derivative. The treatment of [2-(Et₂NCH₂)C₆H₄]₂Se₂ with elemental sodium in THF resulted in [2-(Et₂NCH₂)C₆H₄]SeNa (2). Reactions between alkali metal selenolates [2-(R₂NCH₂)C₆H₄]SeM′ (R = Me, Et; M′ = Li, Na) and MCl₂ (M = Zn, Cd) in a 2:1 molar ratio resulted in the [2-(R₂NCH₂)C₆H₄Se]₂M species [R = Me, M = Zn (3), Cd (4); R = Et, M = Zn (5), Cd (6)]. The new compounds were characterized by multinuclear NMR (¹H, ¹³C, ⁷⁷Se, ¹¹³Cd) and mass spectrometry. The crystal and molecular structures of 1, 3 and 4 revealed monomeric species stabilized by N → Se (for 1) and N → M (for 3 and 4) intramolecular interactions.     

Novel octahedral nickel(II) dithiocarbamates with bi- or tetradentate N-donor ligands: X-ray structures of [Ni(Bzppzdtc)(phen)2]ClO4 · CHCl3 and [Ni(Bz2dtc)2(cyclam)]

A series of novel octahedral nickel(II) dithiocarbamate complexes involving bidentate nitrogen-donor ligands (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) or a tetradentate ligand (cyclam = 1,4,8,11-tetraazacycloteradecane) of the composition [Ni(BzMetdtc)(phen)₂]ClO₄ (1), [Ni(Pe₂dtc)(phen)₂]ClO₄ (2), [Ni(Bzppzdtc)(phen)₂]ClO₄ · CHCl₃ (3), [Ni(Bzppzdtc)(phen)₂](SCN) (4), [Ni(BzMetdtc)(bpy)₂]ClO₄ · 2H₂O (5), [Ni(Pe₂dtc)(cyclam)]ClO₄ (6), [Ni(BzMetdtc)₂(cyclam)] (7), [Ni(Bz₂dtc)₂(cyclam)] (8) and [Ni(Bz₂dtc)₂(phen)] (9) (BzMetdtc = N,N-benzyl-methyldithiocarbamate(1-) anion, Pe₂dtc = N,N-dipentyldithiocarbamate(1-) anion, Bz₂dtc = N,N-dibenzyldithiocarbamate(1-) anion, Bzppzdtc = 4-benzylpiperazinedithiocarbamate(1-) anion), have been synthesized. Spectroscopic (electronic and infrared), magnetic moment and molar conductivity data, and thermal behaviour of the complexes are discussed. Single crystal X-ray analysis of 3 and 8 confirmed a distorted octahedral arrangement in the vicinity of the nickel atom with a N₄S₂ donor set. They represent the first X-ray structures of such type complexes. The catalytic influence of complexes 2, 3, 6, and 7 on graphite oxidation was studied and discussed.     

Synthesis and crystal structure of gallosilicate- and aluminogermanate tetrahydroborate sodalites Na8[GaSiO4]6(BH4)2 and Na8[AlGeO4]6(BH4)2

Tetrahydroborate enclathrated sodalites with gallosilicate and aluminogermanate host framework were synthesized under mild hydrothermal conditions and characterized by X-ray powder diffraction and IR spectroscopy. Crystal structures were refined in the space group P-43n from X-ray powder data using the Rietveld method. Na₈[GaSiO₄]₆(BH₄)₂: a=895.90(1) pm, V=0.71909(3)×10⁻⁶ nm³, R_P=0.074, R_B=0.022, Na₈[AlGeO₄]₆(BH₄)₂: a=905.89(2) pm, V=0.74340(6)×10⁻⁶ nm³, R_P=0.082, R_B=0.026. The tetrahedral framework T-atoms are completely ordered in each case and the boron atoms are located at the centre of the sodalite cages. The hydrogen atoms of the enclathrated anions were refined on x, x, x positions, restraining them to boron-hydrogen distances of 116.8 pm as found in NaBD₄.The IR-absorption spectra of the novel phases show the typical bands of the tetrahedral group as found in the spectrum of pure sodium boron hydride.The new sodalites are discussed as interesting -containing model compounds which could release pure hydrogen.     

Phase polymorphism of [Zn(DMSO)6](ClO4)2 studied by differential scanning calorimetry

Four solid phases of [Zn(DMSO)₆](ClO₄)₂ have been detected by differential scanning calorimetry (DSC). Specifically, the phase transitions were detected between: metastable phase KII ↔ supercooled phase K0 at , stable phase KIb ↔ stable phase KIa at , stable phase KIa ↔ stable phase K0 at . At T_m2 = 389 K crystals partially and at T_m1 = 465 K completely melts. From the entropy change values it was concluded that the phases: K0 and K0′ are the orientationally dynamically disordered phases, so called ODDIC crystals, and phases KIa, KIb and metastable KII are dynamically ordered but with some degree of positional disorder.     

Synthesis and structural investigation of the compounds containing HF2 anions: Ca(HF2)2, Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6)

Three new compounds Ca(HF₂)₂, Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) were obtained in the system metal(II) fluoride and anhydrous HF (aHF) acidified with excessive PF₅. The obtained polymeric solids are slightly soluble in aHF and they crystallize out of their aHF solutions. Ca(HF₂)₂ was prepared by simply dissolving CaF₂ in a neutral aHF. It represents the second known compound with homoleptic HF environment of the central atom besides Ba(H₃F₄)₂. The compounds Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) represent two additional examples of the formation of a polymeric zigzag ladder or ribbon composed of metal cation and fluoride anion (MF⁺)_n besides PbF(AsF₆), the first isolated compound with such zigzag ladder. The obtained new compounds were characterized by X-ray single crystal diffraction method and partly by Raman spectroscopy. Ba₄F₄(HF₂)(PF₆)₃ crystallizes in a triclinic space group P1¯ with a=4.5870(2) Å, b=8.8327(3) Å, c=11.2489(3) Å, α=67.758(9)°, β=84.722(12), γ=78.283(12)°, V=413.00(3) Å³ at 200 K, Z=1 and R=0.0588. Pb₂F₂(HF₂)(PF₆) at 200 K: space group P1¯, a=4.5722(19) Å, b=4.763(2) Å, c=8.818(4) Å, α=86.967(10)°, β=76.774(10)°, γ=83.230(12)°, V=185.55(14) ų, Z=1 and R=0.0937. Pb₂F₂(HF₂)(PF₆) at 293 K: space group P1¯, a=4.586(2) Å, b=4.781(3) Å, c=8.831(5) Å, α=87.106(13)°, β=76.830(13)°, γ=83.531(11)°, V=187.27(18) Å³, Z=1 and R=0.072. Ca(HF₂)₂ crystallizes in an orthorhombic Fddd space group with a=5.5709(6) Å, b=10.1111(9) Å, c=10.5945(10) Å, V=596.77(10) Å³ at 200 K, Z=8 and R=0.028.     

[Cu(men)2(BF4)2] (men = N-methyl-1,2-diaminoethane): Preparation, crystal structure, spectroscopic and magnetic properties

Single crystals of [Cu(men)₂(BF₄)₂] (men = N-methyl-1,2-diaminoethane) (1) were isolated from an aqueous-ethanolic system Cu²⁺-men-BF₄⁻. The crystal structure of 1 consists of [Cu(men)₂(BF₄)₂] molecules. Copper ion exhibits usual distorted octahedral coordination; there are two coordinated men ligands in the equatorial plane with Cu-N bonds of 2.0451(12) and 2.0035(12) Å, while the axial positions are occupied by fluorine atoms from BF₄⁻ anions with Cu-F bond of 2.5091(11) Å. The packing of the [Cu(men)₂(BF₄)₂] molecules is governed by N-H?F type hydrogen bonds. The measured ESR spectrum corroborated the presence of Jahn-Teller anisotropy of Cu(II) with g_|| = 2.20 and g_⊥ = 2.06. The magnetic studies in the temperature range 300-2 K reveal that 1 follows the Curie-Weiss law with parameters g = 2.1612(1) and θ = −0.233(1) K suggesting the presence of weak antiferomagnetic interactions.     

Assembly molecular architectures based on structural variation of metalloligand [Cu(PySal)2] (PySal = 3-pyridylmethylsalicylideneimino)

A versatile neutral metalloligand [Cu(PySal)₂] (1) (PySal = 3-pyridylmethylsalicylidene-imino) was exploited as a building unit to construct five complexes {Cu[Cu(PySal)₂]₂}(ClO₄)₂ (2), {Cd[Cu(PySal)₂]₂(H₂O)₂]} (NO₃)₂ · 2H₂O · 4CH₃OH (3), {Zn[μ₂-Cu(PySal)₂]Cl₂}_n · nCH₃OH (4), {Hg[μ₂-Cu(PySal)₂]I₂}_n (5) and {Cd[μ₂-Cu(PySal)₂]Cl₂}_n · nCH₂Cl₂ (6). [Cu(PySal)₂] acts as a chelating ligand in discrete complexes 2 and 3 with unbound anions, but as a bis-monodentate bridging ligand in polymers 4, 5 and 6 when halogen anions coordinated cooperatively to metal cations. The coordination geometry of Cu²⁺ is well-defined square planar in bridging [Cu(PySal)₂], analogous to that in free metalloligand (1), but it is distorted square planar in chelating [Cu(PySal)₂].     

Infrared and Raman studies of the anion ordering transitions in paramagnetic organometallic radical cation salts [Cp2Mo(dmit)]X (X = PF6, SbF6)

Temperature dependence of infrared and Raman spectra of the two isostructural salts [Cp₂Mo(dmit)]PF₆ and [Cp₂Mo(dmit)]SbF₆ is studied. At room temperature the physical properties of both compounds are very similar but at lower temperatures they undergo phase transitions associated with anion ordering, which are surprisingly different. The phase transitions in [Cp₂Mo(dmit)]PF₆ salt at T₁ = 120 K and T₂ = 89 K have no important influence on infrared and Raman spectra, while the phase transition in [Cp₂Mo(dmit)]SbF₆ salt at T₁ = 175 K causes a splitting of Raman bands assigned to the CC stretching at about 1334 cm⁻¹ and the in-plane Mo(dmit) ring deformation at about 353 cm⁻¹, and also an infrared band at about 939 cm⁻¹ related to the C-S stretching. The splitting of vibrational bands demonstrates a clear distortion of [Cp₂Mo(dmit)]⁺ cations in the [Cp₂Mo(dmit)]SbF₆ salt. This molecular distortion is related to a lattice distortion providing thus a good argument for applicability of the compressible model of the anion ordering transition.     

Synthesis of novel salts with HF, AsF3 and XeF2 as ligands to metal cations

A review of all known compounds of the type [Mⁿ(L)_m](AF₆)_n (M is a metal in the oxidation state n; A = P, As, Sb and Bi; L = HF, AsF₃ and XeF₂) is given with the emphasis on the compounds isolated and characterized by our group. The synthetic routes for the preparation of these compounds are given together with a brief analysis of their structures. In the case of L = XeF₂ the influence of the properties of the cation and the anion on the structural diversity of these coordination compounds is discussed. A brief analysis of their Raman spectra is also given.     

Synthesis and coordinating properties of the facultative Sb2O- and As2O-donor ligands O{(CH2)2ER2}2 (E = Sb or As; R = Ph or Me)

The new mixed Sb₂O-donor ligands O{(CH₂)₂SbR₂}₂ (R = Ph, 1; R = Me, 2) with flexible backbones have been prepared in good yields as air-sensitive oils from reaction of NaSbR₂ with 0.5 mol equivalents of O(CH₂CH₂Br)₂ in thf solution. The As₂O-donor analogues, O{(CH₂)₂AsR₂}₂ (R = Ph, 3; R = Me, 4) were obtained similarly from LiAsPh₂ or NaAsMe₂, respectively and O(CH₂CH₂Br)₂, although ligand 4 appears to be considerably less stable with respect to C-O bond fission under some conditions than the other ligands. Using O(CH₂CH₂Cl)₂ leads only to partial substitution by the SbPh₂⁻ or AsPh₂⁻ nucleophile. These ligands behave as bidentate chelating Sb₂- or As₂-donors in the distorted tetrahedral [M(L-L)₂]BF₄ (M = Cu or Ag; L-L = 1-4) on the basis of solution ¹H and ⁶³Cu NMR spectroscopic studies, mass spectrometry and microanalyses. Crystal structures of three representative examples with Cu(I) and Ag(I) confirm the distorted tetrahedral Sb₄ or As₄ coordination at the metal and allow comparisons of geometric parameters. The crystallographic identification of an unexpected Cu(I)-Cu(I) complex, [Cu₂{Me₂As(CH₂)₂OH}₃](BF₄)₂, obtained as a by-product via C-O bond fission within ligand 4 is also reported. The distorted octahedral [RhCl₂(L-L)₂]Cl and the distorted square planar cis-[PtCl₂(L-L)] (L-L = 1 or 2) are also described. The ether O atoms are not involved in coordination to the metal ion in any of the late transition metal complexes isolated.     

Jahn-Teller-distorted dimeric anions in (cat)[Mn2F8(H2O)2]·2H2O (cat = pipzH2, dabcoH2) and (dabcoH2)2[Mn2F8(H2PO4)2]

Using biprotonated dabco (1,4-diazabicyclo[2.2.2]octane) or pipz (piperazine) as counter cations, mixed-ligand fluoromanganates(III) with dimeric anions could be prepared from hydrofluoric acid solutions. The crystal structures were determined by X-ray diffraction on single crystals: dabcoH₂[Mn₂F₈(H₂O)₂]·2H₂O (1), space group P2₁, Z = 2, a = 6.944(1), b = 14.689(3), c = 7.307(1) Å, β = 93.75(3)°, R₁ = 0.0240; pipzH₂[Mn₂F₈(H₂O)₂]·2H₂O (2), space group , Z = 2, a = 6.977(1), b = 8.760(2), c = 12.584(3) Å, α = 83.79(3), β = 74.25(3), γ = 71.20(3)°, R₁ = 0.0451; (dabcoH₂)₂[Mn₂F₈(H₂PO₄)₂] (3), space group P2₁/n, Z = 4, a = 9.3447(4), b = 12.5208(4), c = 9.7591(6) Å, β = 94.392(8)°, R₁ = 0.0280. All three compounds show dimeric anions formed by [MnF₅O] octahedra (O from oxo ligands) sharing a common edge, with strongly asymmetric double fluorine bridges. In contrast to analogous dimeric anions of Al or Fe(III), the oxo ligands (H₂O (1,2) or phosphate (3)) are in equatorial trans-positions within the bridging plane. The strong pseudo-Jahn-Teller effect of octahedral Mn(III) complexes is documented in a huge elongation of an octahedral axis, namely that including the long bridging Mn-F bond and the Mn-O bond. In spite of different charge of the anion in the fluoride phosphate, the octahedral geometry is almost the same as in the aqua-fluoro compounds. The strong distortion is reflected also in the ligand field spectra.     

Hetero-metallic frameworks of [Pd(CN)4] and Cu(II) with triamines: A rare example of a tetracyanometallate bridged 2D coordination polymer

Four cyano bridged Cu(II)–Pd(II) heterometallic complexes, [Cu(dpt)Pd(CN)₄]_n (1), {[Cu₂(medpt)₂Pd(CN)₄](ClO₄)₂ · 3H₂O}_n (2), {[Cu₂(dien)₂Pd(CN)₄](ClO₄)₂ · 2CH₃OH}_n (3) and {[Cu₂(iPrdien)₂Pd(CN)₄](ClO₄)₂ · 2H₂O}_n (4) [dpt = 3,3′-iminobispropylamine; medpt = 3,3′-diamino-N-methyldipropylamine; dien = diethylenetriamine and iprdien = N′-isopropyldiethylenetriamine] have been synthesized and characterized by single crystal X-ray diffraction analysis, magnetic measurement and thermal study. Complexes 1, 2 and 3 are 1D coordination polymers, while 4 presents a 2D network. In 1, the cis-directed cyanide ligands of [Pd(CN)₄]²⁻ anions link two Cu(dpt) units to form a neutral coordination polymer, whereas in 2, 3 and 4, all the cyanide groups of [Pd(CN)₄]²⁻ take part in bonding with four adjacent Cu(II) ions, resulting in cationic coordination polymers counterbalanced by perchlorate anions. The structures are compared with those of analogous [Ni(CN)₄]²⁻ derivatives. The magnetic behavior shows antiferromagnetic interactions in all the complexes.     

Syntheses and X-ray crystallographic studies of {[Ni(en)2(pot)2]0.5CHCl3} and [Ni(en)2](3-pytol)2

Two novel Ni(II) complexes {[Ni(en)₂(pot)₂]0.5CHCl₃} (3) {pot = 5-phenyl-1,3,4-oxadiazole-2-thione} (1) and [Ni(en)₂](3-pytol)₂ (4) {3-pytol = 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol} (2) have been synthesized using en as coligand. The metal complexes have been characterized by physical and analytical techniques and also by single crystal X-ray studies. The complexes 3 and 4 crystallize in monoclinic system with space group P21/a and P121/c, respectively. The complex 3 has a slightly distorted octahedral geometry with trans (pot)⁻ ligands while 4 has a square planar geometry around the centrosymmetric Ni(II) center with ionically linked trans (3-pytol)⁻ ligands. The π?π (face to face) interaction plays an important role along with hydrogen bondings to form supramolecular architecture in both complexes.     

X-ray single crystal structures of Hg(AuF6)2 and AgFAuF6

Hg(AuF₆)₂ crystallizes at 200 K in the orthorhombic space group Pbcn (No. 60) with a = 917.67(7) pm, b = 971.59(8) pm, c = 962.04(8) pm, and Z = 4. Mercury atoms are coordinated by eight fluorine atoms with six short and two long Hg-F contacts. HgF₈ polyhedra share their four vertices and two edges with six AuF₆ units forming a tridimensional framework.The results of X-ray diffraction analysis on single crystals of AgFAuF₆ are in agreement with previously known powder X-ray diffraction data (Casteel et al, J. Solid State Chem. 96 (1992) 84-96). AgFAuF₆ crystallizes orthorhombic in the space group Pnma (No. 62), a = 717.06(7) pm, b = 761.67(7) pm, c = 1013.61(10) pm at 200 K, Z = 4.     

Synthesis, crystal structure and bioactivity of a novel 18-metallacrown-6 [Mn6(H2O)6 (anshz)6] · 10DMF

A novel macrocyclic hexanuclear manganese(III) 18-metallacrown-6 compound, [Mn₆(H₂O)₆ (anshz)₆] · 10DMF, has been prepared using a trianionic pentadentate ligand N-acetyl-5-nitrosalicylhydrazide (anshz³⁻) and characterized by X-ray diffraction (DMF = N,N-dimethylformamide). The crystal structure contains a neutral 18-membered metallacrown ring consisting of six Mn(III) and six anshz³⁻ ligands. The 18-membered metallacrown ring is formed by the succession of six structural moieties of the type [Mn(III)NN]. Due to the meridional coordination of the ligand to the Mn³⁺ ion, the ligand enforces the stereochemistry of the Mn³⁺ ions as a propeller configuration with alternating Δ/Λ forms. The disc-shaped hexanuclear ring shows at its largest diameter about 7.14 Å at entrance, about 9.76 Å at the center of the cavity, respectively. Antibacterial screening data showed that the manganese metallacrown has strong antimicrobial activity against Bacillus subtilis.