Gold(I) Formamidinate Clusters: The Structure, Luminescence, and Electrochemistry of the Tetranuclear, Base-Free [Au4(ArNC(H)NAr)4]

The structures of the tetragold(I) formamidinate cluster complexes, [Au₄(ArNC(H)NAr)₄], Ar=C₆H₄-4-OMe (1), C₆H₃-3,5-Cl (2), C₆H₄-4-Me (3), have been characterized by x-ray crystallography. The range of AuAu distances is 2.8–3.0 Å. The angles at AuAuAu are acute and obtuse 70 and 109°, 88 and 91°, and 63 and 116° in 1, 2, and 3, respectively. The four gold atoms are located at the corner of a rhomboid with the formamidinate ligands bridged above and below the near plane of the four Au(I) atoms. The tetranuclear gold(I) complexes show a bright blue-green luminescence under UV light, with an emission at 490 nm and a weak emission at 530 nm in the solid state, at room temp and 77 K. The oxidation of the formamidinate cluster, 1, has been studied electrochemically in 0.1 M Bu₄NPF₆/CH₂Cl₂ at a Pt working electrode with different scan rates. Three waves were obtained, 0.75, 0.95, and 1.09V vs. Ag/AgCl at a scan rate of 500 mV/s, the three waves are reversible. The potentials are independent of the scan rate in the range 50 mV/s to 3 V/s. The current at the third wave is larger than those at the first two.     

Synthesis,Characterization, Luminescence,and Electrochemistry of the Tetranuclear Gold(I) Amidinate Clusters,Precursors to CO Oxidation Catalysts: Au4[(ArNC(H)NAr)]4, Au4[(PhNC(Ph)NPh)]4 and Au4[PhNC(CH3)NPh)4]

A summary of the chemistry of the tetranuclear Au(I) amidinate complexes is presented. Tetranuclear Au(I) amidinate clusters are produced by the reaction of the sodium salt of a amidine ligand with the gold precursor Au(THT)Cl in a (1:1) stoichiometry. The structures of the tetranuclear Au₄[ArNC(H)NAr]₄, Ar = C₆H₄‐4‐OMe, C₆H₃‐3,5‐Cl, C₆H₄‐4‐Me, C₆H₄‐3‐CF₃, C₆F₅, C₁₀H₇ and the tetranuclear Au₄[(PhNC(Ph)NPh]₄ and Au₄[PhNC(CH₃)NPh]₄ have been characterized by X‐ray crystallography. The average Au···Au distance between adjacent Au(I) atoms is ?3.0 Å, typical of compounds having an aurophilic interaction. The four gold atoms are located at the corner of a rhomboid with the amidinate ligands bridged above and below the near plane of the four Au(I) atoms. The angles at Au···Au···Au in the cyclic units are between 70° and 116°. The tetranuclear gold(I) amidinate clusters each show different luminescence behavior. The tetranuclear clusters Au₄[(ArNC(H)NAr]₄, Ar = C₆H₄‐4‐OMe, Ar = C₆H₄‐3‐CF₃, Ar = C₆H₄‐4‐Me and Ar = C₆H₄‐3,5‐Cl are the first tetranuclear gold(I) cluster species from group 11 elements that show fluorescence at room temperature. The tetranuclear naphthyl derivative Ar = C₁₀H₇ is luminescent only at 77 K. The pentafluorophenyl derivative Ar = C₆F₅ does not show any photoluminescence in the solid state nor in the solution. The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes. Electrochemical and chemical oxidation studies of the tetranuclear Au(I) amidinate clusters are presented. The tetranuclear complexes Au₄[ArNC(H)NAr]₄, Ar = C₆H₄‐4‐OMe, Ar = C₆H₄‐4‐Me, and Ar = C₆H₃‐3,5‐Cl, show three reversible waves at 0.75, 0.95, 1.09 V vs. Ag/AgCl at a scan rate of 500 mV/s in 0.1 M Bu₄NPF₆/CH₂Cl₂ at a Pt working electrode in CH₂Cl₂. Three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s are also observed for the tetranuclear complex Au₄[PhNC(Ph)NPh]₄ in CH₂Cl₂. The pentafluorophenyl amidinate derivative, Au₄[ArNC(H)NAr]₄, Ar = C₆F₅ shows no oxidation wave below 1.8 V. Recently it has been shown that Au₄[ArNC(H)NAr]₄ is a very effective catalyst precursor for room temperature CO oxidation.     

Tetranuclear Gold(I) Clusters with Nitrogen Donor Ligands: Luminescence and X-Ray Structure of Gold(I) Naphthyl Amidinate Complex

The syntheses and characterization of gold(I) naphthyl, pentafluorophenyl, and trifluoromethylphenyl amidinate complexes are reported. The tetranuclear clusters are obtained from the reaction of Au(tetrahydrothiophene)Cl with the potassium salt of the corresponding amidinate in a THF solvent. The crystal structures of the gold(I) naphthyl, 2, and pentafluorophenyl, 3, amidinates show a short Au···Au distance of ~3. 0 Å typical of compounds having an aurophilic interaction. The gold atoms are arranged in a square (Au···Au···Au = 87°–92°) in the pentafluorophenyl derivative and in a parallelogram (Au···Au···Au = 68°–110°) in the naphthyl amidinate complexes. The naphthyl and trifluoromethylphenyl complexes are visibly luminescent in the solid state at liquid nitrogen temperature displaying asymmetric emission bands at 538 and 473 nm, respectively. The luminescent lifetimes of these species are in the millisecond range indicating phosphorescent processes.     

基于柔性配体的双核铽配位聚合物[Tb2(tda)3(H2O)2]的合成、晶体结构和荧光性质

在水热条件下,利用硫代羟基二乙酸配体[thiodiglycolic acid=H₂tda]和TbCl₃·nH₂O合成了新型稀土配合物[Tb₂(tda)₃(H₂O)₂]。单晶结构表明,配合物是以共边多面体[Tb₂O₁₆]为基本单元构筑的二维结构,并通过弱相互作用拓展为三维超分子体系。中心原子铽与氧原子的配位数是8和9,分别形成了单帽反四棱柱和三帽三角棱柱构型的空间配位多面体。配体H₂tda在配合物中存在两种配位模式：(a) 双“顺-顺桥式双齿、螯合桥式三齿”模式和(b) 双“螯合双齿、顺-反桥式双齿”模式。荧光光谱研究表明：该配合物在室温下呈现较强的绿色荧光发射。配合物属三斜晶系,空间群P1。     

Synthesis, characterization and antitumor activity of some arylantimony triphenylgermanylpropionates and crystal structures of Ph3GeCH(Ph)CH2CO2SbPh4 and [Ph3GeCH2CH(CH3)CO2]2Sb(4-ClC6H4)3

A series of novel arylantimony(V) triphenylgermanylpropionates with the formula (Ph₃GeCHR¹CHR²CO₂)_nSbAr_(5−n) (R¹=H, Ph; R²=H, CH₃; n=1, 2) were synthesized and characterized by elemental analysis, IR, ¹H-NMR, ¹³C-NMR and mass spectroscopy. The crystal structures of Ph₃GeCH(Ph)CH₂CO₂SbPh₄ and [Ph₃GeCH₂CH(CH₃)CO₂]₂Sb(4-ClC₆H₄)₃ were determined by X-ray diffraction. The in vitro antitumor activities of some selected compounds against five cancer cells are reported.     

Proton magnetic relaxation in [N(CH3)4]2 ZnCl4

Proton spin-lattice relaxation times were measured in polycrystalline tetramethylammonium tetrachlorozincate between 77 and 420 K at several Larmor frequencies. Besides the C₃ reorientation of the methyl groups and the isotropic tumbling of the tetramethylammoniunm ions, the results indicate the inequivalence of these ions. Activation energies for different motions are evaluated.     

Reactivity of 2,3-bis(2-pyridyl)pyrazine with [Re2(CO)8(CH3CN)2]: Molecular structures of [Re2(CO)8(C14H10N4)] and [Re2(CO)8(C14H10N4)Re2(CO)8]

The reaction of the labile compound [Re₂(CO)₈(CH₃CN)₂] with 2,3-bis(2-pyridyl)pyrazine in dichloromethane solution at reflux temperature afforded the structural dirhenium isomers [Re₂(CO)₈(C₁₄H₁₀N₄)] (1 and 2), and the complex [Re₂(CO)₈(C₁₄H₁₀N₄)Re₂(CO)₈] (3). In 1, the ligand is σ,σ′-N,N′-coordinated to a Re(CO)₃ fragment through pyridine and pyrazine to form a five-membered chelate ring. A seven-membered ring is obtained for isomer 2 by N-coordination of the 2-pyridyl groups while the pyrazine ring remains uncoordinated. For 2, isomers 2a and 2b are found in a dynamic equilibrium ratio [2a]/[2b]  =  7 in solution, detected by ¹H NMR (−50 °C, CD₃COCD₃), coalescence being observed above room temperature. The ligand in 3 behaves as an 8e-donor bridge bonding two Re(CO)₃ fragments through two (σ,σ′-N,N′) interactions. When the reaction was carried out in refluxing tetrahydrofuran, complex [Re₂(CO)₆(C₁₄H₁₀N₄)₂] (4) was obtained in addition to compounds 1-3. The dinuclear rhenium derivative 4 contains two units of the organic ligand σ,σ′-N,N′-coordinated in a chelate form to each rhenium core. The X-ray crystal structures for 1 and 3 are reported.     

Defects and Luminescence Behavior of Cubic F23 [(NH4(18-Crown-6))4MnX4] [TlX4]2 (X=Cl, Br) Crystals

Luminescence from [(NH₄(18-Crown-6))₄MnBr₄][TlBr₄]₂ (1), [(NH₄(18-Crown-6))₄MnCl₄][TlCl₄]₂ (2), [(NH₄(18-Crown-6))₂MnBr₄] (3), and [(NH₄(18-Crown-6))₂MnCl₄] (4) was studied in search of new insights regarding crystal defects in 2. Emission from 3 and 4 is normal Mn²⁺(⁴T₁(⁴G)→⁶A₁); that of 2 (λ_max≈520 nm at ca. 300 K and 560 nm at 77 K) is unusual and temperature dependent. Thermal barriers (kJ/mol, assignment): green emission of 1 and 2, T<150 K (1-2, NH⁺₄ rotations), 150<T<250 K (7-14, energy migration among [MnX₄]²⁻), 250<T<300 K (26-35, rotations of 18-Crown-6)); yellow emission of 2: T;<250 K (7-8, energy migration among [MnX₄]²⁻), T>250 K (29 kJ/mol, defect-to-Mn²⁺(⁴T₁(⁴G)) back energy transfer). Crystal data for 4: Space group P2₁/c; Z=4; a=20.173(1) Å; b=9.0144(8) Å; c=20.821(1) Å; β=98.782(5)°; V=3741.9(8) ų; R_w=0.059; R=0.054.     

Tetrakis(triphenylphosphine oxide) complexes of the lanthanide nitrates; synthesis, characterisation and crystal structures of [La(Ph3PO)4(NO3)3]·Me2CO and [Lu(Ph3PO)4(NO3)2]NO3

The reaction of Ln(NO₃)₃·6H₂O (Ln=La, Ce, Pr or Nd) with a sixfold excess of Ph₃PO in acetone formed [Ln(Ph₃PO)₄(NO₃)₃]·Me₂CO. The crystal structure of the La complex shows a nine-coordinate metal centre with four phosphine oxides, two bidentate and one monodentate nitrate groups, and PXRD studies show the same structure is present in the other three complexes. In CH₂Cl₂ or Me₂CO solutions, ³¹P NMR studies show that the complexes are essentially completely decomposed into [Ln(Ph₃PO)₃(NO₃)₃] and Ph₃PO. Similar reactions in ethanol gave [Ln(Ph₃PO)₃(NO₃)₃] only. In contrast for Ln=Sm, Eu or Gd, only the [Ln(Ph₃PO)₃(NO₃)₃] are formed from either acetone or ethanol solutions. For the later lanthanides Ln=Tb–Lu, acetone solutions of Ln(NO₃)₃·6H₂O and Ph₃PO gave [Ln(Ph₃PO)₃(NO₃)₃] only, even with a large excess of Ph₃PO, but from cold ethanol [Ln(Ph₃PO)₄(NO₃)₂]NO₃ (Ln=Tb, Ho–Lu) were obtained. The structure of [Lu(Ph₃PO)₄(NO₃)₂]NO₃ shows an eight-coordinate metal centre with four phosphine oxides and two bidentate nitrate groups. In solution in CH₂Cl₂ or Me₂CO the tetrakis-complexes show varying amounts of decomposition into mixtures of [Ln(Ph₃PO)₃(NO₃)₃], [Ln(Ph₃PO)₄(NO₃)₂]NO₃ and Ph₃PO as judged by ³¹P{¹H} NMR spectroscopy. The [Ln(Ph₃PO)₃(NO₃)₃] also partially decompose in solution for Ln=Dy–Lu, forming some tetrakis(phosphine oxide) species.     

New thallium iodates—Synthesis, characterization, and calculations of Tl(IO3)3 and Tl4(IO3)6, [Tl3Tl(IO3)6]

Two new thallium iodates have been synthesized, Tl(IO₃)₃ and Tl₄(IO₃)₆ [Tl⁺₃Tl³⁺(IO₃)₆], and characterized by single-crystal X-ray diffraction. Both materials were synthesized as phase-pure compounds through hydrothermal techniques using Tl₂CO₃ and HIO₃ as reagents. The materials crystallize in space groups R-3 (Tl(IO₃)₃) and P-1 (Tl₄(IO₃)₆). Although lone-pairs are observed for both I⁵⁺ and Tl⁺, electronic structure calculations indicate the lone-pair on I⁵⁺ is stereo-active, whereas the lone-pair on Tl⁺ is inert.     

Synthesis and molecular structure of [Au3Ru4(μ3-H)(CO)12(PPh3)3]

The title compound can be prepared in good yield by heating either [Ru₄(μ-H)₄(CO)₁₂] or [Au₂Ru₄(μ₃-H)₂(CO)₁₂(PPh₃)₂] with [AuMe(PPh₃)] in toluene. The related compound [Au₃Ru₄(μ₃-H)(μ-dppm)(CO)₁₂(PPh₃)] has also been prepared. Both trigoldtetraruthenium clusters undergo dynamic behaviour in solution, involving intramolecular rearrangement of the metal core, as revealed by variable temperature NMR studies. The crystal structure of [Au₃Ru₄(μ₃-H)(CO)₁₂(PPh₃)₃] has been established by an X-ray diffraction study. The metal atom core comprises a trigonal bipyramidal AuRu₄ unit with two AuRu₂ faces capped by gold atoms.     

Synthesis, vibrational and NMR spectroscopic characterization of [N(CH3)4][IO2F2] and X-ray crystal structure of [N(CH3)4]2[IO2F2][HF2]

The salt, [N(CH₃)₄][IO₂F₂], was prepared from [N(CH₃)₄][IO₃] and 49% aqueous HF, and characterized by Raman, infrared, and ¹⁹F NMR spectroscopy. Crystals of [N(CH₃)₄]₂[IO₂F₂][HF₂] were obtained by reduction of [N(CH₃)₄][cis-IO₂F₄] in the presence of [N(CH₃)₄][F] in CH₃CN solvent and were characterized by Raman spectroscopy and single-crystal X-ray diffraction: C2/m, a = 14.6765(2) Å, b = 8.60490(10) Å, c = 13.9572(2) Å, β = 120.2040(10)°, V = 1523.35(3) Å³, Z = 4 and R = 0.0192 at 210 K. The crystal structure consists of two IO₂⁻F₂ anions that are symmetrically bridged by two H⁻F₂ anions, forming a [F₂O₂I(FHF)₂IO₂F₂]⁴⁻ dimer. The symmetric bridging coordination for the H⁻F₂ anion in this structure represents a new bonding modality for the bifluoride anion.     

Multiparameter equations of state for siloxanes: [(CH3)3-Si-O1/2]2-[O-Si-(CH3)2]i=1,…,3, and [O-Si-(CH3)2]6

This article presents the continuation of the work on the development of technical equations of state for linear and cyclic siloxanes already documented in this journal. The fluids considered herewith are octamethyltrisiloxane (MDM, C₈H₂₄Si₃O₂), decamethyltetrasiloxane (MD₂M, C₁₀H₃₀Si₄O₃), dodecamethylpentasiloxane (MD₃M, C₁₂H₃₆Si₅O₄), dodecamethylcyclohexasiloxane (D₆, C₁₂H₃₆Si₆O₆). The 12-parameter functional form proposed by Span and Wagner has been selected because of its positive characteristics. Siloxanes are produced in bulk quantities and are mostly utilized in the cosmetics industry and, mixed, as high-temperature heat transfer fluids. Furthermore, they are used as working fluids in high-temperature organic Rankine cycle power plants. The available property measurements are carefully evaluated and selected for the optimization of equation of state parameters. For some of the fluids, experimental values are scarce, therefore ad hoc estimation methods have been used to supply more information to the procedure for the optimization of the parameters of the equation of state. In addition, saturated liquid density and vapor pressure measurements are correlated with the equations proposed by Daubert and Wagner–Ambrose, respectively, to provide short, simple, and accurate equations for the computation of these properties. The recently developed isobaric ideal-gas heat capacity correlation for the selected siloxanes is included in the thermodynamic models. The performance of the newly developed equations of state is tested by comparison with experimental data and also with predictions calculated with the Peng–Robinson–Stryjek–Vera cubic EoS, as this model was adopted in previous technical studies. The new thermodynamic models perform significantly better than cubic equations of state. T–s and P  – v$v$ diagrams for all the substances are also reported.     

Two New Octahedral Cd(II) Complexes [Cd(L)2] and {[Cd(LH)2(SCN)2]H2O} [L = C6H5C(OH)NN = C(CH3)C5H4N]: Synthesis and Structural Studies

Two new octahedral Cd(II) complexes [Cd(L)₂] (1) and {[Cd(LH)₂(SCN)₂]H₂O} (2) [where LH = C₁₄H₁₃N₃O] are synthesized using a tridentate hydrazone ligand (LH) and they are characterized by elemental analysis, IR spectra, NMR spectra, thermal studies and finally the structures have been determined by single crystal X-ray diffraction. Complex 1 crystallizes in monoclinic system, space group C2/c with a = 22.565(6) ?, b = 10.252(3) ?, c = 12.187(4) ?, β = 118.851(2)^∘, and Z = 4. Complex 2 also crystallizes in the monoclinic system, space group P2₁/c with a = 9.257(9)?, b = 17.809(2)?, c = 9.548(9)?, β = 107.439(4)^∘, and Z = 2. In 1 the ligand binds the Cd(II) ion in tridentate fashion, whereas in 2 it acts as a bidentate ligand.     

2∞[Yb2(NH2)2( Pz )4][Yb(NH3)2( Pz )3 Pz H]: Electride Induced Synthesis of a 2D-Ytterbium-Pyrazolate Network

Summary. ² _∞[Yb₂(NH₂)₂(Pz)₄][Yb(NH₃)₂(Pz)₃ PzH], Pz ⁻ = pyrazolate anion, PzH = pyrazole, C₃H₄N₂ is obtained by the reaction of ytterbium metal with pyrazole in liquid ammonia and subsequent increase of the temperature to 200°C resulting in the formation of colorless single crystals of the compound. The X-ray single crystal analysis reveals that the structure consists of ² _∞[Yb₂(NH₂)₂(Pz)₄] planes with neutral [Yb(NH₃)₂(Pz)₃ PzH] monomeric molecules that are located between the planes and ytterbium is trivalent. This is the first example of a two-dimensional network structure of an organic amine of the rare earth elements that derives from an electride induced synthesis. The product decomposes under release of ammonia outside its sealed reaction vessel, viz. if the NH₃ pressure is removed.     

[H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4]·4[H2O]: A new layered aluminum phosphate-oxalate

A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H₃N(CH₂)₄NH₃]₂[Al₄(C₂O₄)(H₂PO₄)₂(PO₄)₄]·4[H₂O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, ³¹P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7) Å, b=8.8608(8) Å, c=13.2224(11) Å, α=80.830(6)°, β=74.965(5)°, γ=78.782(6)°, Z=2, R_1[I>2σ(I)]=0.0511 and wR_{2(all data)}=0.1423. The alternation of AlO₄ tetrahedra and PO₄ tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO₆ octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO₆, and bridging the adjacent AlO₆ octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions.     

[H2en]2{La2M(SO4)6(H2O)2} (M=Co, Ni): First organically templated 3d-4f mixed metal sulfates

The first organically templated 3d-4f mixed metal sulfates, [H₂en]₂{La₂M(SO₄)₆(H₂O)₂} (M=Co 1, Ni 2) have been synthesized and structurally determined from non-merohedrally twinned crystals. The two compounds are isostructural and their structures feature a three-dimensional anionic network formed by the lanthanum(III) and nickel(II) ions bridged by sulfate anions. The La(III) ions in both compounds are 10-coordinated by four sulfate anions in bidentate chelating fashion, and two sulfate anions in a unidentate fashion. The transition metal(II) ion is octahedrally coordinated by six oxygens from four sulfate anions and two aqua ligands. The doubly protonated enthylenediamine cations are located at the tunnels formed by 8-membered rings (four La and four sulfate anions).     

Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pr2C6H3)

The compounds [MoCl(NAr)₂R] (R=CH₂CMe₂Ph (1) or CH₂CMe₃(2); Ar=2,6-Prⁱ₂C₆H₃) have been prepared from [MoCl₂(NAr)₂(dme)] (dme=1,2-dimethoxyethane) and one equivalent of the respective Grignard reagent RMgCl in diethyl ether. Similarly, the mixed-imido complex [MoCl₂(NAr)(NBu^t)(dme)] affords [MoCl(NAr)(NBu^t)(CH₂CMe₂Ph)] (3). Chloride substitution reactions of 1 with the appropriate lithium reagents afford the compounds [MoCp(NAr)₂(CH₂CMe₂Ph)] (4) (Cp=cyclopentadienyl), [MoInd(NAr)₂(CH₂CMe₂Ph)] (5) (Ind=Indenyl), [Mo(OBu^t)(NAr)₂(CH₂CMe ₂Ph)] (6), [MoMe(NAr)₂(CH₂CMe₂Ph)] (7), [MoMe(PMe₃)(NAr)₂(CH₂CMe ₂Ph)] (8) (formed in the presence of PMe₃) and [Mo(NHAr)(NAr)₂(CH₂CMe₂P h)](9). In the latter case, a by-product {[Mo(NAr)₂(CH₂CMe₂Ph) ]₂(μ-O)}(10) has also been isolated. The crystal structures of 1, 4, 5 and 10 have been determined. All possess distorted tetrahedral metal centres with cis near-linear arylimido ligands; in each case (except 5, for which the evidence is unclear) there are α-agostic interactions present.     

Tuning the sulfur-heterometal interaction in organolead(IV) complexes of [Pt2(μ-S)2(PPh3)4]

Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with Ph₃PbCl, Ph₂PbI₂, Ph₂PbBr₂ and Me₃PbOAc result in the formation of bright yellow to orange solutions containing the cations [Pt₂(μ-S)₂(PPh₃)₄PbR₃]⁺ (R₃ = Ph₃, Ph₂I, Ph₂Br, Me₃) isolated as PF₆⁻ or BPh₄⁻ salts. In the case of the Me₃Pb and Et₃Pb systems, a prolonged reaction time results in formation of the alkylated species [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (R = Me, Et). X-ray structure determinations on [Pt₂(μ-S)₂(PPh₃)₄PbMe₃]PF₆ and [Pt₂(μ-S)₂(PPh₃)₄PbPh₂I]PF₆ have been carried out, revealing different coordination modes. In the Me₃Pb complex, the (four-coordinate) lead atom binds to a single sulfur atom, while in the Ph₂PbI adduct coordination of both sulfurs results in a five-coordinate lead centre. These differences are related to the electron density on the lead centre, and indicate that the interaction of the heterometal centre with the {Pt₂S₂} metalloligand core can be tuned by variation of the heteroatom substituents. The species [Pt₂(μ-S)₂(PPh₃)₄PbR₃]⁺ display differing fragmentation pathways in their ESI mass spectra, following initial loss of PPh₃ in all cases; for R = Ph, loss of PbPh₂ occurs, yielding [Pt₂(μ-S)₂(PPh₃)₃Ph]⁺, while for R = Me, reductive elimination of ethane gives [Pt₂(μ-S)₂(PPh₃)₃PbMe]⁺, which is followed by loss of CH₄.     

[COH(NH2)2]2[Cu(pic)2(ClO4)2]的合成与晶体结构

The title compound was synthesized by reaction of Cu(ClO₄)₂， picolinic acid and carbamide in C₂H₅OH/CH₃CN solution， and characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system， space group Pbca with a=14.0481(8)， b=9.0130(5)， c=18.626(1)?， V=2358.3(2)?³， Z=4， D_x=1.771g·cm^-3， μ=1.235mm^-1 and F(000)=1276. The final R factor is 0.0440 for 1434 observed reflections. The X-ray analysis revealed that the copper(Ⅱ) atom is coordinated by two picolinic ligands in the equatorial plane， while the two oxygen atoms of perchlorate occupy the axial positions of octahedron with lengthened Cu-O distances， resulting in a 4+2 elongated octahedral environment. In the compound， there also exist two protonated carbamide cations for charge balance. CCDC： 195354.