Structure and Bonding of the Hexameric Platinum(II) Dichloride,Pt6Cl12 (β‐PtCl2)

The crystal structure of Pt₆Cl₁₂ (β‐PtCl₂) was redetermined ( a_h = 13.126Å, c_h = 8.666Å, Z = 3; a_rh = 8.110Å, α = 108.04°; 367 hkl, R = 0.032). As has been shown earlier, the structure is in principle a hierarchical variant of the cubic structure type of tungsten (bcc), which atoms are replaced by the hexameric Pt₆Cl₁₂ molecules. Due to the 60° rotation of the cuboctahedral clusters about one of the trigonal axes, the symmetry is reduced from to ( ). The molecule Pt₆Cl₁₂ shows the (trigonally elongated) structure of the classic M₆X₁₂ cluster compounds with (distorted) square‐planar PtCl₄ fragments, however without metal‐metal bonds. The Pt atoms are shifted outside the Cl₁₂ cuboctahedron by Δ = +0.046Å ( (Pt—Cl) = 2.315Å; (Pt—Pt) = 3.339Å). The scalar relativistic DFT calculations results in the full symmetry for the optimized structure of the isolated molecule with d(Pt—Cl) = 2.381Å, d(Pt—Pt) = 3.468Å and Δ = +0.072Å. The electron distribution of the Pt‐Pt antibonding HOMO exhibits an outwards‐directed asymmetry perpendicular to the PtCl₄ fragments, that plays the decisive role for the cluster packing in the crystal. A comparative study of the Electron Localization Function with the hypothetical trans‐(Nb₂Zr₄)Cl₁₂ molecule shows the distinct differences between Pt₆Cl₁₂ and clusters with metal‐metal bonding. Due to the characteristic electronic structure, the crystal structure of Pt₆Cl₁₂ in space group is an optimal one, which results from comparison with rhombohedral Zr₆I₁₂ and a cubic bcc arrangement.     

Trans Influence of Triphenylstibine: Crystal Structures of cis‐[PtBr2(SbPh3)2], trans‐[PtBr(Ph)(SbPh3)2], [NMe4][PtBr3(SbPh3)], and cis‐[PtBr2(SbPh3)(PPh3)]

The work reports the unexpected reaction of diphenyldibromo antimonates (III) with PtCl₂ and cis‐[PtCl₂(PPh₃)₂]. The reaction gives triphenylstibine containing Pt^II complexes viz. cis‐[PtBr₂(SbPh₃)₂] ( 1 ), trans‐[[PtBr(Ph)(SbPh₃)₂] ( 2 ), [NMe₄][PtBr₃(SbPh₃)] ( 3 ), and cis‐[PtBr₂(PPh₃)(SbPh₃)] ( 4 ). All the complexes were characterised by elemental analyses, IR, Raman, ¹⁹⁵Pt NMR, FAB mass spectroscopy and X‐ray crystallography. A plausible mechanism via the phenyl migration is proposed for the formation of these complexes. The average Pt–Br distance in 1 is 2.456(2) Å, in 2 2.496 Å(trans to Ph) while in 3 it is 2.476 Å (trans to Sb) implying a comparable trans influence of Ph₃Sb and Ph₃P.     

Gerüstverbindungen mit beweglichen LaIII‐Kationen: Synthesen,Kristallstrukturen und Strukturdynamik der Lanthan(III)‐Eisen(II)‐Sulfid‐Halogenide La53Fe12S90X3 (X = Cl,Br, I)

Framework Compounds with Mobile La^III Cations: Syntheses, Crystal Structures and Structural Dynamics of the Lanthanum(III) Iron(II) Sulfide Halides La₅₃Fe₁₂S₉₀X₃ (X = Cl, Br, I) Black crystals of La₅₃Fe₁₂S₉₀X₃ (X = Cl, Br, I) were synthesized from La₂S₃ and FeS in a reactive LaX₃ flux at 1320 K. The structures were determined by single‐crystal X‐ray diffraction. The compounds are isostructural, crystallizing in the rhombohedral space group with Z = 1 (La₅₃Fe₁₂S₉₀Cl₃: a = 14.0154(7), c = 21.888(1) Å, V = 3723.5(3) ų; La₅₃Fe₁₂S₉₀Br₃: a = 14.0048(9), c = 22.040(2) Å, V = 3743.6(4) ų; La₅₃Fe₁₂S₉₀I₃: a = 13.9805(8), c = 22.108(2) Å, V = 3742.2(4) ų). The structure adopted is a stuffed variant of the La₅₂Fe₁₂S₉₀ structure type. [Fe^II₂S₉] dimers of face‐sharing octahedra are linked by face‐ and vertex‐sharing bi‐ or tri‐capped [La^IIIS_6+n] trigonal prisms, forming a three‐dimensional framework containing cuboctahedral cavities of two sizes. The larger cavities, which remain empty in the structure of La₅₂Fe₁₂S₉₀, are filled by halide ions in La₅₃Fe₁₂S₉₀X₃. The smaller cavities accommodate numerous sites for disordered lanthanum cations, modelling a network of diffusion pathways through the structure. An analogous picture is obtained from the calculation of the periodic nodal surface (PNS): The PNS separates a labyrinth containing the framework atoms from a labyrinth containing the mobile lanthanum cations. Molecular dynamic simulations confirm a strong coupling between the motions of the mobile lanthanum ions and the neighbouring sulfide ions.     

Syntheses of Trifluoromethanethiolato Platinum(II) Complexes – Crystal Structures of cis‐Pt(SCF3)2(PPh3)2 and trans‐Pt(SCF3)Cl(PPh3)2

Ligand exchange reactions of cis‐PtCl₂(PPh₃)₂ and [NMe₄]SCF₃ in different ratios were studied. Depending on the stoichiometry reactions proceeded with formation of products expected for the chosen ratio, i. e. cis‐Pt(SCF₃)Cl(PPh₃)₂, cis‐Pt(SCF₃)₂(PPh₃)₂, and [NMe₄][Pt(SCF₃)₃(PPh₃)]. Starting from cis‐PtCl₂(MeCN)₂ and [NMe₄]SCF₃ and adding PPh₃ after substitution, product mixtures were dominated by the corresponding trans‐isomers. Results of the single crystal structure analyses of cis‐Pt(SCF₃)₂(PPh₃)₂ and trans‐Pt(SCF₃)Cl(PPh₃)₂ are discussed.     

The Reaction of the Betain‐like Compound O2C2(PPh3)2 with [(cod)PtI2] – Crystal Structure of the Salt (HC{PPh3}2)[(η3‐C8H11)PtI2]

The reaction of the betain‐like compound O₂C₂(PPh₃)₂ ( 1 ) with [(cod)PtX₂] in THF solution gives the salt‐like compounds (HC{PPh₃}₂)[(η³‐C₈H₁₁)PtX₂] ( 3 , X = I; 4 , X = Cl) in about quantitative yields. The new η³‐bonded C₈H₁₁ ligand is the result of a proton transfer from the coordinated cod ligand to 1 with subsequent release of CO₂. The X‐ray analysis of 3 shows the presence of two isomers in a 60:40 ratio, which differ in the bonding of the C₈H₁₁ ligand. 3 crystallizes in the triclinic space group with the unit cell dimensions a = 1091.7(1), b = 1141.5(1), c = 1649.4(2) pm; α = 80.34(1)°, β = 83.62(1)°, γ = 89.03(1)°, V = 2013.7(4)·10⁶ pm³, Z = 2.     

Hydrogen Bonding Network of 4‐Amidiniumpyridine Acetate and PtIIbis(triphenylphosphine) Complexes with 4‐Amidine­pyridine

The X‐ray structures of 4‐amidiniumpyridine acetate, ( 1· H)AcO, and of cis‐[Pt( 1 )₂(PPh₃)₂](NO₃)₂ ( 2 ), as well as their IR spectra, reveal intramolecular hydrogen bonding, which held together the cations and the anions. The IR spectroscopic data suggest that this may be so also in cis‐[PtCl( 1 )(PPh₃)₂](BF₄) ( 3 ). In ( 1· H)AcO and in 2 extensive intermolecular hydrogen bonding networks span through the whole crystals.     

Synthesis,Characterization and Crystal Structures of new Palladium(II) Complexes and the first Platinum(III) Complex Containing ATT (ATT = 6‐Aza‐2‐thiothymine)

Treatment of the ligand 6‐aza‐2‐thiothymine (ATT, HL, 1 ) with palladium chloride in methanol forms the ionic complex [(HL)₄Pd]Cl₂·8MeOH ( 2 ), while its reaction with palladium iodide in same solvent produces the neutral complex trans‐[(HL)₂PdI₂]·2MeOH ( 3 ) in high yields. The reaction of 1 with Na₂[PdCl₄] in the presence of sodium acetate in a molar ratio of 2:1:2 and with platinum(II) chloride in presence of sodium acetate led to the dimer tetranuclear complexes [(L₄Pd₂)NaCl]₂·8MeOH ( 4 ) and [L₄Pt₂Cl₂]·6MeOH·H₂O ( 5 ). The latter is the first Pt^III complex of the ligand. All complexes were characterized by elemental analyses and IR spectroscopy and the crystal structures of 2 , 3 , 4 and 5 are determined by single‐crystal X‐ray diffraction. Crystal data for 2 at ?80 °C: triclinic space group , a = 1006.6(1), b = 1006.9(1), c = 1158.1(1) pm, α = 85.20(1)°, β = 83.84(1)°, γ = 88.91(1)°, Z = 1, R₁ = 0.0278; for 3 at ?80 °C: triclinic space group , a = 490.5(1), b = 977.2(2), c = 1116.8(2) pm, α = 90.26(1)°, β = 102.33(1)°, γ = 96.08(1)°, Z = 1, R₁ = 0.0394; for 4 at ?80 °C: orthorhombic space group Ccca, a = 1791.7(2), b = 1874.1(2), c = 2044.0(1) pm, Z = 4, R₁ = 0.0341 and for 5 at ?80 °C: monoclinic space group P2₁/c, a = 1464.3(1), b = 2003.7(1), c = 1368.5(1) pm, β = 95.66(1)°, Z = 4, R₁ = 0.0429.     

A Mixed‐Valent Uranium Phosphonate Framework Containing UIV,UV, and UVI

It is shown that U^VO₂⁺ ions can reside at U^VIO₂²⁺ lattice sites during mild reduction and crystallization process under solvothermal conditions, yielding a complicated and rare mixed‐valent uranium phosphonate compound that simultaneously contains U^IV, U^V, and U^VI. The presence of uranium with three oxidation states was confirmed by various characterization techniques, including X‐ray crystallography, X‐ray photoelectron, electron paramagnetic resonance, FTIR, UV/Vis‐NIR absorption, and synchrotron radiation X‐ray absorption spectroscopy, and magnetism measurements.     

Pt2(HSO4)2(SO4)2, the First Binary Sulfate of Platinum

Red single crystals of Pt₂(HSO₄)₂(SO₄)₂ were obtained by the reaction of elemental platinum with conc. sulfuric acid at 350 °C in sealed glass ampoules. The crystal structure (monoclinic, P2₁/c, Z = 2, a = 868.6(2), b = 826.2(1), c = 921.8(2) pm, β=116.32(1)°, R_all = 0.0348) shows dumbbell shaped Pt₂⁶⁺ cations which are coordinated by four SO₄^2— and two HSO₄^— ions. Each of the sulfate ions is attached to another Pt₂⁶⁺ ion yielding layers according to equation/tex2gif-stack-1.gif[Pt₂(SO₄)_4/2(HSO₄)_2/1]. The layers are connected by hydrogen bonds with the OH group of the hydrogensulfate ion as donor and the non‐bonding oxygen atom of the sulfate ion as acceptor.     

Darstellung,Kristallstrukturen und Schwingungsspektren neuer ternärer Verbindungen mit dem Anion [N–B–N]3–

Ternary Nitridoborates. 2. Synthesis, Crystal Structure, and Vibrational Spectra of New Ternary Compounds with the [N–B–N]^3– Anion The isotypic compounds LiM₄[BN₂]₃ (M = Ca, Sr, Ba, Eu) and NaM₄[BN₂]₃ (M = Sr, Ba) are formed as colorless to pale yellow prismatic crystals (black with Eu) by reaction of the binary components Li₃N, M₃N₂, EuN and Na, NaN₃, Ba₃N₂ and BN in sealed niobium ampoules at 1375 and 1275 K, respectively. The linear anions [N–B–N]^3– have bond lengths d(B–N) between 132.6 and 136.6 pm. Vibrational frequencies and force constants f(B–N) = 7.25–7.89 Ncm^–1 reveal significant drifts related to bond length and effective anionic charge. The cubic crystal structures (Im3m (No. 229), Z = 2; LiM₄[BN₂]₃: a(Ca) = 711.5 pm; a(Sr) = 745.6 pm; a(Eu) = 742.5 pm, a(Ba) = 788.0 pm and NaM₄[BN₂] ${}_{\text{3}\text{: a(Sr) = 756.8 pm; a(Ba) = 791.7 pm)) are stuffed derivatives of the β‐PtHg4}}$ structure type, and the range of existence of this cubic structure is derived from the molar volume and the ionic radii. The cations form a partial structure of centered cubes E1(E2)₈ which are condensed to a [E1(E2)_8/2] network (E1 = Li, Na; E2 = Ca, Sr, Ba, Eu). The remaining open cubes are filled by the [BN₂]^3– anions yielding two interpenetrating [E1(BN₂)_6/2] networks. Periodic Nodal Surfaces (PNS) of Im3m symmetry show the regions of different interactions.     

Preparation,Crystal Structure,Physical Properties,and Electronic Band Structure of TlTaS3

TlTaS₃ was prepared by applying a sequence of two melting processes with mixtures of Tl₂S, Ta, and S having different molar metal to sulphur ratios. TlTaS₃ crystallises in space group Pnma with a = 9.228(3)Å, b = 3.5030(6)Å, c = 14.209(3)Å, V = 459.3(2)ų, Z = 4. The structure is closely related to the NH₄CdCl₃‐type. Characteristic features of the structure are chains of edge‐sharing [Ta(+5)S₄S_2/2]₂ double octahedra running along [010]. These columns are linked by Tl⁺ ions. The Tl⁺ ion is surrounded by eight S^2— anions to form a distorted bi‐capped trigonal prism. The Tl⁺ ions are shifted from the centre of the trigonal prism toward one of the rectangular faces. This is discussed in context with other isostructural compounds. TlTaS₃ is a semiconductor. The electronic structure is discussed on the base of band structure calculations performed within the framework of density functional theory.     

Mixed‐Valence Thallium(I,III) Bromides The Crystal Structure of α—Tl2Br3

Thallium sesquibromide Tl₂Br₃ is dimorphic. Scarlet coloured crystals of α‐Tl₂Br₃ were obtained by reactions of aqueous solutions of TlBr₃ and Tl₂SO₄ in agarose gel. In case of rapid crystallisation of hydrous TlBr₃/TlBr solutions and from TlBr/TlBr₂ melts ß‐Tl₂Br₃ is formed as scarlet coloured, extremely thin lamellae. The crystal structures of both forms are very similar and can be described as mixed‐valence thallium(I)‐hexabromothallates(III) Tl₃[TlBr₆]. In the monoclinic unit cell of α‐Tl₃[TlBr₆] (a = 26.763(7) Å; b = 15.311(6) Å; c = 27.375(6) Å; β = 108.63(2)°, Z = 32, space gr. C2/c) the 32 Tl^III‐cations are found in strongly distorted octahedral TlBr₆ groups. The 96 Tl^I cations are surrounded either by four or six TlBr₆ groups with contacts to 8 or 9 Br neighbors. Crystals of β‐Tl₃[TlBr₆] by contrast show almost hexagonal metrics (a = 13.124(4) Å, b = 13.130(4) Å, c = 25.550(7) Å, γ = 119.91(9)°, Z = 12, P2₁/m). Refinements of the parameters revealed structural disorder of TlBr₆ units, possibly resulting from multiple twinning. Both structures are composed of Tl₂[TlBr₆]^— and Tl₄[TlBr₆]⁺ multilayers, which alternate parallel (001). The structural relationships of the complicated structures of α‐ and β‐Tl₃[TlBr₆] to the three polymorphous forms of Tl₂Cl₃ as well as to the structures of monoclinic hexachlorothallates M₃TlCl₆ (M = K, Rb) and the cubic elpasolites are discussed.     

Molecular Gold Wire from Mixed‐Valent AuI/III Complexes

Crystals of mixed‐valent Au complexes have been grown from solutions of cyclohexanecarbonitrile and a stoichiometric amount of gold(I) and gold(III) chloride. The purely obtained compound was characterized as bis(cyclohexanecarbonitrile)gold(I) tetrachloridoaurate(III). The crystal packing of the mixed valent Au(I/III) compound demonstrates a columnar arrangement of the gold(I) and gold(III) atoms. The new structure displays the shortest unsupported gold(I)–gold(III) interactions with the sub‐van der Waals distance of 324–325 pm, which is assumed as an aurophilic bonding interaction.     

The Metallic Zintl Phase Ba3Si4 – Synthesis,Crystal Structure,Chemical Bonding,and Physical Properties

The Zintl phase Ba₃Si₄ has been synthesized from the elements at 1273 K as a single phase. No homogeneity range has been found. The compound decomposes peritectically at 1307(5) K to BaSi₂ and melt. The butterfly‐shaped Si₄⁶⁻ Zintl anion in the crystal structure of Ba₃Si₄ (Pearson symbol tP28, space group P4₂/mnm, a = 8.5233(3) Å, c = 11.8322(6) Å) shows only slightly different Si‐Si bond lengths of d(Si–Si) = 2.4183(6) Å (1×) and 2.4254(3) Å (4×). The compound is diamagnetic with χ ≈ −50 × 10⁻⁶ cm³ mol⁻¹. DC resistivity measurements show a high electrical resistivity (ρ(300 K) ≈ 1.2 × 10⁻³ Ω m) with positive temperature gradient dρ/dT. The temperature dependence of the isotropic signal shift and the spin‐lattice relaxation times in ²⁹Si NMR spectroscopy confirms the metallic behavior. The experimental results are in accordance with the calculated electronic band structure, which indicates a metal with a low density of states at the Fermi level. The electron localization function (ELF) is used for analysis of chemical bonding. The reaction of solid Ba₃Si₄ with gaseous HCl leads to the oxidation of the Si₄⁶⁻ Zintl anion and yields nanoporous silicon.     

Fractional Site Occupation in Ternary Metal Compounds: Structure, Bonding, and Thermodynamics

Summary. Ternary compounds of the type (M,M′)_xA_y where M and M′ are early transition metals of the groups 4–6 and A is a main group element of the groups 14–16 are showing interesting substitution mechanisms among the metal atoms ranging from classical and partially ordered solid solution phases to ternary compounds showing differential fractional site occupation. In these compounds the transition metals show mixed site occupation at the metal positions in combination with pronounced site preferences leading to varying metal mixtures at crystallographically independent sites. The connection between partial ordering and the differences in the local coordination of the respective lattice sites is discussed. Chemical bonding arguments obtained from electronic calculations using the extended Hückel approach are used to understand the observed distribution of the metals over the respective lattice sites and allow a qualitative prediction of site preferences. A thermodynamic model was applied in order to investigate the observed substitution mechanism and Gibbs energies for the occupation of the lattice sites with different metal atoms could be obtained by adjusting the model parameters to the experimentally observed site fractions.     

Synthesis,Crystal Structure and Density Functional Studies on 1N‐Phenyl‐3‐(2,4‐Dichlorophenyl)‐5‐(4‐Chlorophenyl)‐2‐Pyrazoline

1N‐Phenyl‐3‐(2,4‐dichlorophenyl)‐5‐(4‐chlorophenyl)‐2‐pyrazoline has been synthesized and characterized by elemental analysis, IR, UV‐Vis and X‐ray single crystal diffraction. Density functional calculations have been carried out for the title compound by using the B3LYP method with a 6‐311G** basis set. The calculated results show that the predicted geometry can reproduce well the structural parameters. The electronic absorption spectra calculated in the gas phase are better than those calculated in EtOH solvent to model the experimental electronic spectra. Natural Bond Orbital (NBO) analyses suggest that the above electronic transitions are mainly assigned to π → π* transitions. On the basis of vibrational analyses, the thermodynamic properties of the compound at different temperatures have been calculated, revealing the correlations between C⁰_{p, m}, S⁰_m, H⁰_m and temperature.     

Structural and Spectroscopic Evidence for Marginal Metal‐to‐Ligand Charge Transfer in Complexes Pt(abpy)Me3X,abpy = 2,2′‐Azobispyridine,X = Cl,Br, I

The title complexes (X = Cl, 1a ; X = Br, 1b ; X = I, 1c ) could be characterized by ¹H‐NMR spectroscopy and were partially studied by X‐ray diffraction ( 1b,c ), cyclic voltammetry and UV‐Vis spectroscopy ( 1b ). The short N=N bonds of about 1.26Å, the occurrence of only weak charge transfer absorptions in the visible, the rather small shift of the reduction potential, and the small g anisotropy in the EPR spectrum of 1b^{˙ ?} indicate an only a marginal π interaction between the organometallic Pt^IV fragments and the excellent π acceptor abpy.     

Synthesis and characterisation of the platinum complexes [PtCl(CClPAr)(PPh3)2] and [PtCl(CClPAr′)(PPh3)2] as potential intermediates in the preparation of phosphaalkynes

Oxidative addition reactions of Cl₂CPR (R = 2,4,6-tris(trifluoromethyl)phenyl (Ar) or 2,6-bis(trifluoromethyl)phenyl (Ar′) with Pt(PPh₃)₄ yield the cis and trans (at platinum) complexes [PtCl(ClCPAr)(PPh₃)₂] and [PtCl(ClCPAr′)(PPh₃)₂]. All starting materials and intermediates have been characterised by NMR spectroscopy. The crystal and molecular structures of the trans-platinum complexes have been determined by single-crystal X-ray diffraction at low temperature.