Theoretical study of the structure and water affinity of [M(18C6)(HFA)<Subscript>2</Subscript>] complexes for M = Zn,Cu, Hg,Co, Ni,and Pt

The structures of the [M(18C6)]²⁺ cations, where M = Zn, Cu, Hg, Ni, Co, and Pt, and cis- and trans-[M(18C6)(HFA)₂]/[M(18C6)(NO₃)₂] molecules in the gas phase have been calculated by the density functional theory method in the B3LYP/6-31G*//6-311++G** + LanL2Dz approximation. Geometry optimization has been performed, and the strength of binding of the central cation to the crown ether (18C6) and the degree of structural similarity of the [M(18C6)(HFA)₂] compounds for different central atoms M have been evaluated. For all [M(18C6)(NO₃)₂]/[M(18C6)(HFA)₂] molecules (M = Zn, Cu, Hg, Ni, Co, Pt), the vertical ionization potential and the vertical electron affinity have been calculated. These parameters are of interest for analysis of the stability of volatile compounds [M(18C6)(HFA)₂] to donor–acceptor interactions with other components of the gas phase, for example, with water vapor, which is usually a Lewis base with respect to the systems in question and can donate electron density in the course of complexation with the central atom. The propensity of the [M(18C6)(NO₃)₂]/[M(18C6)(HFA)₂] molecules to react with water is considered for a wider range of metals M²⁺ = Ba²⁺, Sr²⁺, Pb²⁺, Mn²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Hg²⁺, Co²⁺, Ni²⁺, and Pt²⁺, with taking into account the degree of matching between the ionic radii of M²⁺ cations and the 18C6 cavity size.     

Primary Fragmentation Pathways of Gas Phase [M(Uracil−H)(Uracil)]+ Complexes (M=Zn,Cu, Ni,Co, Fe,Mn, Cd,Pd , Mg,Ca, Sr,Ba, and Pb): Loss of Uracil versus HNCO

Complexes formed between metal dications, the conjugate base of uracil, and uracil are investigated by sustained off‐resonance irradiation collision‐induced dissociation (SORI‐CID) in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Positive‐ion electrospray spectra show that [M(Ura?H)(Ura)]⁺ (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd, Mg, Ca, Sr, Ba, or Pb) is the most abundant ion even at low concentrations of uracil. SORI‐CID experiments show that the main primary decomposition pathway for all [M(Ura?H)(Ura)]⁺, except where M=Ca, Sr, Ba, or Pb, is the loss of HNCO. Under the same SORI‐CID conditions, when M is Ca, Sr, Ba, or Pb, [M(Ura?H)(Ura)]⁺ are shown to lose a molecule of uracil. Similar results were observed under infrared multiple‐photon dissociation excitation conditions, except that [Ca(Ura?H)(Ura)]⁺ was found to lose HNCO as the primary fragmentation product. The binding energies between neutral uracil and [M(Ura?H)]⁺ (M=Zn, Cu, Ni, Fe, Cd, Pd ,Mg, Ca, Sr Ba, or Pb) are calculated by means of electronic‐structure calculations. The differences in the uracil binding energies between complexes which lose uracil and those which lose HNCO are consistent with the experimentally observed differences in fragmentation pathways. A size dependence in the binding energies suggests that the interaction between uracil and [M(Ura?H)]⁺ is ion–dipole complexation and the experimental evidence presented supports this.     

Synthesis and Characterization of One-dimensional Dicyclohexyl-18-crown-6 Complexes with M2[Cd(mnt)2] (M = Na, K)

Two supramolecular crown ether complexes [Na(DC18C6-A)(H₂O)]{[Na(DC18C6-A)][Cd(mnt)₂]} (1) and [K(DC18C6-A)]₂[Cd(mnt)₂] (2) (DC18C6-A = cis-syn-cis-dicyclohexyl-18-crown-6, isomer A; mnt = maleonitriledithiolate) have been synthesized and characterized by elemental analysis, FT-IR spectroscopy and X-ray single crystal diffraction. Complex 1 is composed of one [Na(DC18C6-A)(H₂O)]⁺ complex cation and one {[Na(DC18C6-A)][Cd(mnt)₂]}⁻ complex anion and displays an infinite chain-like structure through N–Na–N interactions. In complex 2, [K(DC18C6-A)]⁺ complex cation and [Cd(mnt)₂]²⁻ complex anion afford a novel 1D ladder-like structure by N–K–N, N–K–S interactions.     

M(benzo‐18‐crown‐6)I4 (M = Cd,Hg): Tetraiodide,Iodide–Iodine Adduct,or an Inclusion Compound of Iodine in MI2@(benzo‐18‐crown‐6)?

M(benzo‐18‐crown‐6)I₄ (M = Cd, Hg) are obtained as red columnar crystals from the reactions of benzo‐18‐crown‐6 (b18c6), cadmium and mercury iodide, respectively, and iodine in molar ratios of 1:1:2 in acetonitrile. They both crystallize with the orthorhombic crystal system, P2₁2₁2₁, a = 833.7(1), b = 1610.9(1), c = 1846.8(1) pm, V = 2480.3(1) 10⁶·pm³, Z = 4, for M = Cd and a = 823.4(1), b = 1616.5(1), c = 1866.1(1) pm, V = 2483.8(2) 10⁶·pm³ for M = Hg. The crystal structures consist of [M(b18c6)]I₂ molecules which are connected to a slightly lengthened iodine molecule via a secondary contact, according to the formulation I₂@[MI₂@(b18c6)].     

One‐dimensionally linked Chain Crown Ether Complexes. Syntheses and Crystal Structures of Complexes [K(18‐Crown‐6)]2[M(SeCN)4](H2O) (M = Pd,Pt)

18‐crown‐6(18‐C‐6) complexes with K₂[M(SeCN)₄] (M = Pd, Pt): [K(18‐C‐6)]₂[Pd(SeCN)₄] (H₂O) ( 1 ) and [K(18‐C‐6)]₂[Pt(SeCN)₄](H₂O) ( 2 ) have been isolated and characterized by elemental analysis, IR spectroscopy and single crystal X‐ray analysis. The complexes crystallize in the monoclinic space group P2₁/n with cell dimensions: 1 : a = 1.1159(3) Å, b = 1.2397(3) Å, c = 1.6003(4) Å, β = 92.798(4)°, V = 2.2111(8) ų, Z = 2, F(000) = 1140, R₁ = 0.0418, wR₂ = 0.0932 and 2 : a = 1.1167(3) Å, b = 1.2394(3) Å, c = 1.5968(4) Å, β = 92.945(4)°, V = 2.2071(9) ų, Z = 2, F(000) = 1204, R₁ = 0.0341, wR₂ = 0.0745. Both complexes form one‐dimensionally linked chains of [K(18‐C‐6)]⁺ cations and [M(SeCN)₄]^2— (M = Pd, Pt) anions bridged by K‐O‐K interactions between adjacent [K(18‐C‐6)]⁺ units.     

Metal(II) hexafluorophosphates(V) (M = Sr, Pb) containing XeF(2)-coordinated metal ions [M(XeF(2))(3)](PF(6))(2), [Pb(3)(XeF(2))(11)](PF(6))(6), and [Sr(3)(XeF(2))(10)](PF(6))(6)

From the system MF(2)/PF(5)/XeF(2)/anhydrous hydrogen fluoride (aHF), four compounds [Sr(XeF(2))(3)](PF(6))(2), [Pb(XeF(2))(3)](PF(6))(2), [Sr(3)(XeF(2))(10)](PF(6))(6), and [Pb(3)(XeF(2))(11)](PF(6))(6) were isolated and characterized by Raman spectroscopy and X-ray single-crystal diffraction. The [M(XeF(2))(3)](PF(6))(2) (M = Sr, Pb) compounds are isostructural with the previously reported [Sr(XeF(2))(3)](AsF(6))(2). The structure of [Sr(3)(XeF(2))(10)](PF(6))(6) (space group C2/c; a = 11.778(6) Angstrom, b = 12.497(6) Angstrom, c = 34.60(2) Angstrom, beta = 95.574(4) degrees, V = 5069(4) Angstrom(3), Z = 4) contains two crystallographically independent metal centers with a coordination number of 10 and rather unusual coordination spheres in the shape of tetracapped trigonal prisms. The bridging XeF(2) molecules and one bridging PF(6)- anion, which connect the metal centers, form complicated 3D structures. The structure of [Pb(3)(XeF(2))(11)](PF(6))(6) (space group C2/m; a = 13.01(3) Angstrom, b = 11.437(4) Angstrom, c = 18.487(7) Angstrom, beta = 104.374(9) degrees, V = 2665(6) Angstrom(3), Z = 2) consists of a 3D network of the general formula {[Pb(3)(XeF(2))(10)](PF(6))(6)}n and a noncoordinated XeF(2) molecule fixed in the crystal structure only by weak electrostatic interactions. This structure also contains two crystallographically independent Pb atoms. One of them possesses a unique homoleptic environment built up by eight F atoms from eight XeF(2) molecules in the shape of a cube, whereas the second Pb atom with a coordination number of 9 adopts the shape of a tricapped trigonal prism common for lead compounds. [Pb(3)(XeF(2))(11)](PF(6))(6) and [Sr(3)(XeF(2))(10)](PF(6))(6) are formed when an excess of XeF(2) is used during the process of the crystallization of [M(XeF(2))(3)](PF(6))(2) from their aHF solutions.     

A novel PtII–dibenzo‐18‐crown‐6 (DB18C6) complex

The novel Pt^II–dibenzo‐18‐crown‐6 (DB18C6) title complex, μ‐[tetrakis­(thio­cyanato‐S)­platinum(II)]‐N:N′‐bis{[2,5,8,­15,18,21‐hexa­oxa­tri­cyclo­[20.4.0.1^9,14]­hexa­cosa‐1(22),9(14),10,12,23,25‐hexaene‐κ⁶O]­potassium(I)}, [K(C₂₀H₂₄O₆)]₂[Pt(SCN)₄], has been isolated and characterized by X‐ray diffraction analysis. The structure analysis shows that the complex displays a quasi‐one‐dimensional infinite chain of two [K(DB18C6)]⁺ complex cations and a [Pt(SCN)₄]^2? anion, bridged by K⁺?π interactions between adjacent [K(DB18C6)]⁺ units.     

Interaction of Molybdenum(VI) Oxyanions with +2 Metal Cations

The association of molybdenum(VI) oxyanions with metal cations was investigated in solutions of low ionic strength, such as those prevailing in most natural waters. Potentiometric titrations were carried out for the systems containing molybdenum(VI) anions and divalent metal cations (M = Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg and Pb). This selection includes the major cations and some other cations of high environmental relevance. The interaction of iron(III) with Mo(VI) anions was also studied. At neutral and basic pH values and for those systems where the solubility of the molybdate salt is high enough, ionic species pairs such as [M(MoO₄)] predominate. At acidic pH values, [M(HMoO₄)]⁺ and [M(Mo₇O₂₄)]^4– are formed, the latter species are only relevant for total molybdenum concentrations higher than 1 mmol·L^?1. These results provide the basis for molybdenum speciation in natural aquatic systems, on which the environmental fate, bioavailability and toxicity of the element depend.     

Darstellung von Acetatoblei(IV)- und Acetatozinn(IV)- manganpentacarbonylen durch Acidolyse von (C6H5)4–n−M[Mn(CO)5]n (M  Sn,Pb; n = 1, 2) mit Essigsäure

Preparation of Acetatolead(1V) and Acetatotin(1V) Manganese Pentacarbonyls by Acidolysis of (C₆H₅)_4?n M[Mn(CO)₅]_n (M ? Sn, Pb; n = 1, 2) with Acetic Acid By acidolysis of (C₆H₅)_4?nM[Mn(CO)₅]_n (M ? Sn, Pb; n = 1, 2) with acetic acid no M? Mn bonds are broken, but M? C bonds. In this reaction (CH₃COO)₂M[Mn(CO)₅]₂ is formed from (C₆H₅)₂M[Mn(CO)₅]₂, and (CH₃COO)₃SnMn(CO)₅ and (CH₃COO)₂C₆H₅PbMn(CO)₅ from (C₆H₅)₃MMn-(CO)₅. (CH₃COO)₂C₆H₅SnMn(CO)₅ is prepared from Cl₂C₆H₅SnMn(CO)₅ and AgCH₃COO. According to IR spectroscopic data the acetato ligands of the diacetato complexes are bidentate, while in (CH₃COO)₃SnMn(CO)₅ bi- and monodentate carboxylate groups are present. For the central atoms Sn and Pb octahedral coordination is proposed.     

Verbindungsbildung in den quasi-binären Systemen AcX4?MX2 (Ac = Th,U; M = Ca,Sr, Ba,Eu, Ge,Sn, Pb; X = Br,I)

Formation of Compounds in the Quasi-binary Systems AcX₄? MX₂ (Ac = Th, U; M = Ca, Sr, Ba, Eu, Ge, Sn, Pb; X = Br, I) T,x-phase diagrams of the systems ThI₄? SnI₂, ThI₄? PbI₂, ThI₄? CaI₂, and ThI₄? SrI₂ were established using thermoanalysis and x-ray methods. The only ternary compounds have a 1:1 composition. Further AcMX₆ compounds (Ac: Th, U; M: Ca, Sr, Ba, Eu, Ge, Sn, Pb; X: Br, I) were synthesized and their structures investigated. Four structure types are found depending on the temperature and the Ac/M combinations. The structures of γ-ThSnI₆ and β-ThSnI₆ were determined with single crystal methods as representatives of a whole series of isotypic compounds.     

Alkalimetalltetraethinylozincate und ‐cadmate AI2M(C2H)4 (AI = Na — Cs,M = Zn,Cd): Synthese,Kristallstruktur und spektroskopische Eigenschaften

Alkali Metal Tetraethinylozincates and ‐cadmates A^I₂M(C₂H)₄ (A^I = Na — Cs, M = Zn, Cd): Synthesis, Crystal Structures, and Spectroscopic Properties By reaction of A^IC₂H (A^I = Na — Cs) with divalent zinc and cadmium salts in liquid ammonia the alkali metal tetraethinylozincates and ‐cadmates A^I₂M(C₂H)₄ (M = Zn, Cd) were accessible as polycrystalline powders. While Na₂M(C₂H)₄ is amorphous to X‐rays and the crystal structure of Cs₂Zn(C₂H)₄ could not be solved up to now, the remaining compounds are isotypic to the already known crystal structures of the potassium compounds, as was deduced from powder diffraction with X‐rays and synchrotron radiation. They crystallise in the tetragonal space group I4₁a, contain [M(C₂H)₄]^2— tetrahedra and show structural relationships to the scheelit and anatas structure types. Raman spectroscopic investigations confirm the existence of tetrahedral fragments with C‐C triple bonds in the alkali as well as in the amorphous alkaline earth metal compounds A^IIM(C₂H)₄ (A^II = Mg — Ba, M = Zn, Cd).     

An IR and Raman study of trigonal triple molybdates M 5 I M 0.5 II Hf1.5(MoO4)6 (MI = K, Tl; MII = Ca, Sr, Ba, Pb)

The vibration spectra of triple molybdates M ₅ ^I M _0.5 ^II Hf_1.5(MoO₄)₆ (M^I = K, Tl; M^II = Ca, Sr, Ba, Pb) were examined. The internal vibration frequencies of molybdate groups were assigned. The double-charged cations affect the symmetric stretching (v₁), bending, and translation vibration frequencies in the Raman spectra. In the IR spectra, the triply degenerate stretching vibration of the MoO₄ group (～890–720 cm^?1) is split, and the splitting increases with an increase in the radius of the double-charged cation.     

Synthese und Kristallstruktur von [Ba(18-Krone-6)(DMF)4][Cd(Se4)2]

Synthesis and Crystal Structure of [Ba(18-Crown-6)(DMF)₄][Cd(Se₄)₂] The title compound has been prepared by the reaction of a DMF-solution of lithium polyselenide with BaSe₂ and cadmium acetate in the presence of 18-crown-6, forming black crystals. The compound was characterized by IR spectroscopy and by an X-ray structure determination. Space group P2/a, Z = 4, 5392 observed unique reflections, R = 0.048. Lattice dimensions at ?90°C: a = 2021.9(12); b = 1019.8(6); c= 2270.8(14)pm, ß = 106.98(4)°. The structure consists of [Ba(18-crown-6)(DMF)₄]²⁺ ions, in which the barium ions are coordinated by the six oxygen atoms of the crown ether molecule and by four oxygen atoms of the DMF molecules, and of [Cd(Se₄)₂]^2? ions. The cadmium atoms are coordinated by two tetraselenide ions in a chelating fashion.     

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.     

Vibrational spectroscopic studies on the en-Td-type benzene clathrates: M(ethylenediamine)M′(CN)4·2C6H6 (M=Mn or Cd,M′=Cd or Hg)

IR spectra of Mn(en)M(CN)₄·2C₆H₆ (M=Cd or Hg), and IR and Raman spectra of Cd(en)M(CN)₄·2C₆H₆ (M=Cd or Hg) clathrates are reported. The spectral features suggest that the first two compounds are similar in structure to the later two Td-type clathrates.     

M(SCN)2 (M = Eu,Sr, Ba): Kristallstruktur,thermisches Verhalten,Schwingungsspektroskopie

M(SCN)₂ (M = Eu, Sr, Ba): Crystal Structure, Thermal Behaviour, Vibrational Spectroscopy Single crystals of M(SCN)₂ (M = Eu, Sr, Ba) have been obtained via metathesis of NaSCN and MCl₂ (M = Eu, Sr, Ba) at 340 °C. The isotypic crystal structures of the thiocyanates M(SCN)₂ (C2/c, Z = 4, Eu: a = 979.3(2), b = 660.8(1), c = 815.7(2) pm, β = 91.58(3)°, R_all = 0.0245, Sr: a = 985.5(2), b = 662.9(2), c = 819.6(2) pm, β = 91.29(3)°, R_all = 0.0435, Ba: a = 1018.8(2), b = 687.2(1), c = 852.2(1) pm, β = 92.43(2)°, R_all = 0.0392) contain alternating layers of M²⁺ and SCN^–. According to M(SCN)_4/4(NCS)_4/4 M²⁺ is eight‐coordinated by four sulfur and four nitrogen atoms forming a square antiprism. Thermal investigations show that the compounds melt without decomposition. Vibrational spectroscopic investigations are presented and discussed.     

Vibrational Spectroscopic Studies on the Td-type Adeninemetal(II)tetracyanometallate(II) Benzene Clathrates: M(ad)2M'(CN)4.C6H6 (M = Mn or Cd, M' = Cd or Hg)

IR spectra of Mn(adenine)₂M(CN)₄.C₆H₆ (M=Cd or Hg), andIR and Raman spectra of Cd(adenine)₂M(CN)₄.C₆H₆(M=Cd or Hg) are reported. The spectral data suggest thatthe host frameworks of these compounds are similarto those of the Hofmann-T_d-type and the adeninecoordination is via N(10).     

Synthesis and crystal structure of aqua(dibenzo-18-crown-6)potassium (dibenzo-18-crown-6)-(tetrachlorocuprato(II)-Cl)potassium

New mixed complex compound aqua(dibenzo-18-crown-6)potassium (dibenzo-18-crown-6)(tetrachlorocuprato(II)-Cl)potassium, [K(CuCl₄)(Db18C6)]^? · [K(Db18C6)(H₂O)]⁺, is synthesized and its crystal structure is studied by the method of x-ray structural analysis. The structure includes two independent complex ions, both of guest-host type: two cations K⁺ are located in the respective cavities of the Db18C6 crown-ligand (one in each) and each is coordinated by all its six O atoms and one Cl atom of the anion-ligand [CuCl₄]^2? or O atom of the ligand water molecule. Coordination of these two K⁺ cations is completed to hexagonal pyramidal one by formation by each of unusually weak coordination bond K⁺ → π(\(C\dddot - C\)) with two C atoms of respective benzene ring in the neighboring Db18C6 ligand. In this crystal structure the complex anions and cations form dual infinite chains via these coordination bonds and interionic O-H?Cl hydrogen bonds.     

Die Clusterazide M2[Nb6Cl12(N3)6]·(H2O)4—x (M = Ca,Sr, Ba)

The Cluster Azides M₂[Nb₆Cl₁₂(N₃)₆]·(H₂O)_4—x (M = Ca, Sr, Ba) The isotypic cluster compounds M₂[Nb₆Cl₁₂(N₃)₆] · (H₂O)_4—x (M = Ca (1) , M = Sr (2) and M = Ba (3) ) have been synthesized by the reaction of an aequeous solution of Nb₆Cl₁₄ with M(N₃)₂. 1 , 2 and 3 crystallize in the space group Fd3¯ (No. 227) with the lattice constants a = 1990.03(23), 2015.60(12) and 2043, 64(11) pm, respectively. All compounds contain isolated 16e— clusters whose terminal positions are all occupied by orientationally disordered azide ligands.     

Luminescence de l'Europium Divalent dans les Fluosilicates MSiF6 (M = Sr,Ba)

Luminescence of Eu²⁺ Ions in Fluosilicates MSiF₆ (M = Sr, Ba) A pure f → f emission is detected in Eu²⁺ doped SrSiF₆ and BaSiF₆. Because of the strong ionic bonding of europium a large gap occurs between the bottom of the 5d band and the ⁶P_7/2 emission level (3000 cm^?1 at 300 K). The emission is very intense under low pressure mercury excitation and decreases slowly with temperature.