Facile Insertion of Carbon Dioxide into Cu2(μ‐H) Dinuclear Units Supported by Tetraphosphine Ligands

Reactions of meso‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) with Cu^I species in the presence of NaBH₄ afforded di‐ and tetranuclear copper hydride complexes, [Cu₂(μ‐H)(μ‐dpmppm)₂]X ( 1 ) and [Cu₄(μ‐H)₂(μ₄‐H)(μ‐dpmppm)₂]X ( 2 ) (X=BF₄, PF₆). Complex 1 undergoes facile insertion of CO₂ (1 atm) at room temperature, leading to a formate‐bridged dicopper complex [Cu₂(μ‐HCOO)(dpmppm)₂]X ( 3 ). The experimental and DFT theoretical studies clearly demonstrate that CO₂ insertion into the Cu₂(μ‐H) unit occurred with the flexible dicopper platform. Complex 2 also undergoes CO₂ insertion to give a formate‐bridged complex, [Cu₄(μ‐HCOO)₃(dpmppm)₂]X, during which the square Cu₄ framework opened up to a linear tetranuclear chain.     

Facially Dispersed Polyhydride Cu9 and Cu16 Clusters Comprising Apex‐Truncated Supertetrahedral and Square‐Face‐Capped Cuboctahedral Copper Frameworks

By using a linear tetraphosphine, meso‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm), nona‐ and hexadecanuclear copper hydride clusters, [Cu₉H₇(μ‐dpmppm)₃]X₂ (X=Cl ( 1 a ), Br ( 1 b ), I ( 1 c ), PF₆ ( 1 d )) and [Cu₁₆H₁₄(μ‐dpmppm)₄]X₂ (X₂=I₂ ( 2 c ), (4/3) PF₆?(2/3) OH ( 2 d )) were synthesized and characterized. They form copper‐hydride cages of apex‐truncated supertetrahedral {Cu₉H₇}²⁺ and square‐face‐capped cuboctahedral {Cu₁₆H₁₄}²⁺ structures. The hydride positions were estimated by DFT calculations to be facially dispersed around the copper frameworks. A kinetically controlled synthesis gave an unsymmetrical Cu₈H₆ cluster, [Cu₈H₆(μ‐dpmppm)₃]²⁺ ( 3 ), which readily reacted with CO₂ to afford linear Cu₄ complexes with formate bridges, leading to an unprecedented hydrogenation of CO₂ into formate catalyzed by {Cu₄(μ‐dpmppm)₂} platform. The results demonstrate that new motifs of copper hydride clusters could be established by the tetraphosphine ligands, and the structures influence their reactivity.     

Platinum(II) Complexes of P‐Chiral 1, 8‐Bis(diorganophosphino)naphthalenes; Crystal Structures of dmfppn,rac‐[PtCl2(dmfppn)], and rac‐[PtCl2(dtbppn)] (dmfppn = 1, 8‐di(methyl‐pentafluorophenylphosphino)naphthalene and dtbppn = 1, 8‐di(tert‐butylphenylphosphino)naphthalene)

The reaction of 1, 8‐dilithionaphthalene 2 , with 2 equivalents of rac‐Me(C₆F₅)PCl, gave a 6 : 1 mixture of rac‐ and meso‐1, 8‐di(methyl‐pentafluorophenylphosphino)naphthalene (dmfppn, rac‐ 3h and meso‐ 3h ), but no reaction was observed when the sterically crowded rac‐tBu(C₆F₅)PCl was used. In ³¹P NMR experiments, rac‐ 3h and mmeso‐ 3h exhibited characteristic signals (virtual quintets), which indicate that there is significant coupling through space (³J_PF + ⁷ J_PF ≈ 15 Hz). Compound rac‐ 3h was isolated by fractional crystallisation and treated with aqueous H₂O₂ to yield the corresponding bis‐phosphine dioxide, rac‐ 7h . In contrast to rac‐ 3h , there was no sign of through‐space coupling in rac‐ 7h , which again illustrates that the latter operates via the lone pairs at phosphorus. Platinum(II) complexes were prepared from the new, P‐chiral chelate rac‐ 3h , and the related ligand 1, 8‐di(tert‐butylphenylphosphino) naphthalene (rac‐dtbppn, rac‐ 3e ). All isolated new compounds were characterised by multinuclear NMR and IR spectroscopy, mass spectrometry, and elemental analysis. Single‐crystal X‐ray structure determinations were performed for rac‐dmfppn (rac‐ 3h ), rac‐[PtCl₂(dtbppn)] (rac‐ 17e ), and rac‐[PtCl₂(dmfppn)] (rac‐ 17h ). rac‐ 3h displays crystallographic twofold symmetry. In rac‐ 17h , the electron‐withdrawing effect of the C₆F₅ groups causes a shortening of the P_t—P bond to ca. 220 pm (cf. 223 pm in rac‐ 17e ).     

Hydrophobic ionic liquid‐based ultrasound‐assisted extraction of magnolol and honokiol from cortex Magnoliae officinalis

The hydrophobic ionic liquid of [BMIM][PF₆] was successfully used for the ultrasound‐assisted extraction of hydrophobic magnolol and honokiol from cortex Magnoliae officinalis. To obtain the best extraction efficiencies, some ultrasonic parameters including the concentration of [BMIM][PF₆], pH, ultrasonic power and ultrasonic time were evaluated. The results obtained indicated that the [BMIM][PF₆]‐based ultrasound‐assisted extraction efficiencies of magnolol and honokiol were greater than those of the [BMIM][BF₄]‐based ultrasound‐assisted extraction (from 48.6 to 45.9%) and the traditional ethanol reflux extraction (from 16.2 to 13.3%). Furthermore, the proposed extraction method is validated by the recovery, correlation coefficient (R²) and reproducibility (RSD, n=5), which were 90.8–102.6, 0.9992–0.9998, and 1.6–5.4%, respectively.     

(n‐Bu4N)2[Au(mnt)2]: Synthese,Struktur‐ und EPR‐Untersuchungen eines stabilen,mononuklearen AuII‐Komplexes

The reaction of [Au^III(mnt)₂]^? with (n‐Bu₄N)[BH₄] in acetone leads to the formation of [Au^II(mnt)₂]^2?, which is the second stable mononuclear Au^II complex characterized by X‐ray structure analysis. (n‐Bu₄N)₂[Au^II(mnt)₂] crystallizes triclinic, P (a = 904.24(5), b = 989.55(5), c = 1627.35(10) pm, α = 92.040(7), β = 94.937(7), γ = 107.220(6)°, Z = 1) with two molecules acetone per unit cell. The anion is planar. From EPR investigations using single crystals of (n‐Bu₄N)₂[Au^II(mnt)₂] the g tensor components were derived. Information about magnetic exchange interactions were obtained from line width analyses.     

Bimodal molecular weight distribution of poly(styrene‐co‐acrylonitrile) formed by conventional free‐radical copolymerization of acrylonitrile and styrene in room temperature ionic liquids

Conventional free‐radical copolymerization of acrylonitrile (AN) and styrene (St) was realized in room temperature ionic liquids (RTILs), 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim][BF₄]) and 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([Bmim][PF₆]), under mild conditions. The copolymerization in RTILs was more rapid than that in traditional solvent DMF. Poly(styrene‐co‐acrylonitrile) (SAN) prepared in RTILs had higher molecular weight than that prepared in DMF or by bulk copolymerization. SAN with bimodal molecular weight distribution (MWD) were obtained in most of the reaction conditions in [Bmim][BF₄] and some conditions in [Bmim][PF₆]. By the analysis of reaction phenomena and fluorescence behavior, the reason of the difference in MWD could be attributed to the difference of reaction system compatibility mainly caused by the immiscibility of macromolecule with RTIL. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4420–4427, 2006     

Anion‐Dependent Tendency of Di‐Long‐Chain Quaternary Ammonium Salts to Form Ion Quadruples and Higher Aggregates in Benzene

The self‐aggregation tendency of [N(CH₃)₂(C₁₈H₃₇)₂]X [ 1 X; X^?=BF₄^?, PF₆^?, OTf^?, NTf₂^?, BPh₄^?, BTol₄^?, BAr^F?, and B(C₆F₅)₄^?] salts to form ion quadruples (IQs) and higher aggregates (HAggs) in [D₆]benzene is investigated by means of diffusion NMR spectroscopy. The experimental results indicate that salts containing small anions ( 1 BF₄, 1 PF₆, and 1 OTf) are present in solution as IQs even at the lowest investigated concentration of C=5×10^?5 M and show a limited tendency to further self‐aggregate, reaching a maximum average aggregation number (N=V_H/${V_{\rm{H}}^{{\rm{0IP}}} }$ , where V_H=measured hydrodynamic volume and ${V_{\rm{H}}^{{\rm{0IP}}} }$ =hydrodynamic volume of the ion pair) of about 6–8 (C=0.050–0.100 M ). Salts with larger counterions [ 1 BPh₄, 1 BTol₄, 1 BAr^F, and 1 B(C₆F₅)₄] form instead ion pairs at low concentration but steadily self‐aggregate (especially the non‐fluorinated ones) on increasing their concentration up to N values exceeding 50 (C=0.030–0.050 M ). 1 NTf₂ behaves in an intermediate fashion. The self‐aggregation tendency of salts is quantified by formulating the dependence of V_H on C by means of the equations of indefinitive aggregation models. The following rankings for the formation of IQs and HAggs are obtained: IQs: 1 BF₄≈ 1 PF₆≈ 1 OTf> 1 NTf₂> 1 B(C₆F₅)₄≥ 1 BPh₄≥ 1 BTol₄≥ 1 BAr^F; HAggs: 1 BTol₄> 1 BPh₄> 1 NTf₂> 1 B(C₆F₅)₄> 1 BAr^F> 1 BF₄≈ 1 PF₆≈ 1 OTf. Interionic NOE NMR studies and DFT calculations were conducted in order to determine the relative anion–cation orientation in the self‐aggregating units.     

Syntheses,Structures, and Properties of Phosphorescent Iridium(III) Complexes Containing N‐Heterocyclic Carbene Ligands

The organic salts 1‐(2‐pyridylmethyl)‐3‐alkylbenzimidazolium halide (pm‐RbH ⁺X⁻) and 1‐(2‐pyridylmethyl)‐3‐alkylimidazolium halide (pm‐R′iH ⁺X′⁻) were prepared (where R = 4‐, 3‐, 2‐fluorobenzyl ( 4f , 3f , and 2f , respectively), 4‐, 3‐, 2‐chlorobenzyl ( 4c , 3c , and 2c , respectively); 4‐methoxybenzyl (4mo); 2,3,4,5,6‐pentafluorobenzyl (f₅); benzyl (b); and methyl (m)); X = Cl and Br; R′ = benzyl (b) and methyl (m); and X′ = Cl and I. From these salts, heteroleptic Ir(III ) complexes containing one N ‐heterocyclic carbene (NHC ) ligand [Ir(κ²‐ppy)₂(κ²‐(pm‐Rb))]PF₆ (R = 4f, 1 (PF₆ ); 3f, 2 (PF₆ ); 2f, 3 (PF₆ ); f₅b, 4 (PF₆ ); 4c, 5 (PF₆ ); 3c, 6 (PF₆ ); 2c, 7 (PF₆ ); 4mo, 8 (PF₆ ); b, 9 (PF₆ ); m, 10 (PF₆ )) and [Ir(κ²‐ppy)₂(κ²‐(pm‐R′i))]PF₆ (R = b, 11 (PF₆ ); m, 12 (PF₆ )), were synthesized, and the crystal structures of 1 (PF₆ ), 2 (PF₆ ), 3 (PF₆ ), 5 (PF₆ ), 6 (PF₆ ), 7 (PF₆ ), 9 (PF₆ ), 10 (PF₆ ), and 12 (PF₆ ) were determined by X‐ray diffraction. The neutral NHC ligands 1‐(2‐pyridylmethyl)‐3‐alkylbenzimidazolin‐2‐ylidene (pm‐Rb) and 1‐(2‐pyridylmethyl)‐3‐alkylimidazolin‐2‐ylidene (pm‐R′i) of all cations were found to be involved in the intermolecular π−π stacking interactions with the surrounding cations in the solid state, thereby probably influencing the photophysical behavior in the solid state and in solution. The absorption and emission properties of all the complexes show only small variations.     

Template‐free anion‐controlled synthesis of Pd (II) nano‐aggregates for the antifouling polymerization of CO and ethylene

The reaction of [(domppp) Pd (OAc)₂] [domppp = 1,3‐bis (di‐o‐methoxyphenylphosphino)propane] and imidazolium‐functionalized carboxylic acids containing various anions (Br^?, PF₆^?, SbF₆^? and BF₄^?) resulted in the formation of nano‐sized Pd (II) aggregates under template‐free conditions. The rate of formation of aggregates can be modulated by changing the anion, affecting the rate of polymerization of CO and olefins without fouling. Herein, we describe the analysis of Pd (II) catalysts by dynamic light scattering, atomic force microscopy, X‐ray photoelectron spectroscopy and X‐ray crystallography, and co‐ and terpolymerization results including the catalytic activity, and bulk density and molecular weight of polymers.     

Ring‐opening polymerization of rac‐ and meso‐lactide initiated by indium bis(phenolate) isopropoxy complexes

Ring‐opening polymerization of rac‐ and meso‐lactide initiated by indium bis(phenolate) isopropoxides {1,4‐dithiabutanediylbis(4,6‐di‐tert‐butylphenolate)}(isopropoxy)indium ( 1 ) and {1,4‐dithiabutanediylbis(4,6‐di(2‐phenyl‐2‐propyl)phenolate)}(isopropoxy)indium ( 2 ) is found to follow first‐order kinetics for monomer conversion. Activation parameters ΔH^? and ΔS^? suggest an ordered transition state. Initiators 1 and 2 polymerize meso‐lactide faster than rac‐lactide. In general, compound 2 with the more bulky cumyl ortho‐substituents in the phenolate moiety shows higher polymerization activity than 1 with tert‐butyl substituents. meso‐Lactide is polymerized to syndiotactic poly(meso‐lactides) in THF, while polymerization of rac‐lactide in THF gives atactic poly(rac‐lactides) with solvent‐dependent preferences for heterotactic (THF) or isotactic (CH₂Cl₂) sequences. Indium bis(phenolate) compound rac‐(1,2‐cyclohexanedithio‐2,2′‐bis{4,6‐di(2‐phenyl‐2‐propyl)phenolato}(isopropoxy)indium ( 3 ) polymerizes meso‐lactide to give syndiotactic poly(meso‐lactide) with narrow molecular weight distributions and rac‐lactide in THF to give heterotactically enriched poly(rac‐lactides). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4983–4991     

Atom transfer radical polymerization using activators regenerated by electron transfer of acrylonitrile in 1‐(1‐ethoxycarbonylethyl)‐3‐methylimidazolium hexafluorophospate

Atom transfer radical polymerization using activators regenerated by electron transfer (ARGET ATRP) of acrylonitrile (AN) was first approached with 1‐(1‐ethoxycarbonylethyl)‐3‐methylimidazolium tetrafluoroborate ([ecemim][BF₄]) as reaction medium and tin(II) bis(2‐ethylhexanoate) (Sn(EH)₂) as reducing agent in the presence of air. When compared with in bulk, an obvious increase of polymer isotacticity was observed for ARGET ATRP of AN in 1‐(1‐ethoxycarbonylethyl)‐3‐methylimidazolium hexafluorophospate ([ecemim][PF₆]), the reaction rate of ARGET ATRP of AN in [ecemim][PF₆] was higher and the polymerization process was better controlled. The block copolymer polyacrylonitrile‐block‐poly(methyl methacrylate) with molecular weight at 69,750, distribution at 1.34, and isotacticity at 0.36 was successfully obtained in [ecemim][PF₆]. [Ecemim][PF₆] and the catalyst system were recycled and reused and had no effect on the living nature of polymerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

The 3[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

The complexes [Au₃(dcmp)₂][X]₃ {dcmp=bis(dicyclohexylphosphinomethyl)cyclohexylphosphine; X=Cl^? ( 1 ), ClO₄^? ( 2 ), OTf^? ( 3 ), PF₆^? ( 4 ), SCN^?( 5 )}, [Ag₃(dcmp)₂][ClO₄]₃ ( 6 ), and [Ag₃(dcmp)₂Cl₂][ClO₄] ( 7 ) were prepared and their structures were determined by X‐ray crystallography. Complexes 2 – 4 display a high‐energy emission band with λ_max at 442–452 nm, whereas 1 and 5 display a low‐energy emission with λ_max at 558–634 nm in both solid state and in dichloromethane at 298 K. The former is assigned to the ³[5dσ*6pσ] excited state of [Au₃(dcmp)₂]³⁺, whereas the latter is attributed to an exciplex formed between the ³[5dσ*6pσ] excited state of [Au₃(dcmp)₂]³⁺ and the counterions. In solid state, complex [Ag₃(dcmp)₂][ClO₄]₃ ( 6 ) displays an intense emission band at 375 nm with a Stokes shift of ≈7200 cm^?1 from the ¹[4dσ*→5pσ] absorption band at 295 nm. The 375 nm emission band is assigned to the emission directly from the ³[4dσ^*5pσ] excited state of 6 . Density functional theory (DFT) calculations revealed that the absorption and emission energies are inversely proportional to the number of metal ions (n) in polynuclear Au^I and Ag^I linear chain complexes without close metal???anion contacts. The emission energies are extrapolated to be 715 and 446 nm for the infinite linear Au^I and Ag^I chains, respectively, at metal???metal distances of about 2.93–3.02 Å. A QM/MM calculation on the model [Au₃(dcmp)₂Cl₂]⁺ system, with Au???Cl contacts of 2.90–3.10 Å, gave optimized Au???Au distances of 2.99–3.11 Å in its lowest triplet excited state and the emission energies were calculated to be at approximately 600–690 nm, which are assigned to a three‐coordinate Au^I site with its spectroscopic properties affected by Au^I???Au^I interactions.     

Hexa‐ and Octagold Chains from Flexible Tetragold Molecular Units Supported by Linear Tetraphosphine Ligands

A flexible building block : Flexible tetragold(I) chain complexes supported by a new single methylene‐bridged tetraphosphine ligand were synthesized and further transformed into discrete linear octagold(I) {Au₈} and cyclic hexagold(I) {Au₆} structures by reaction with KI and NaAuCl₄, respectively (see picture, Au purple, Cl dark green, PF₆ light green, I pink). The tetragold complexes are also luminescent at room temperature.

     

Self‐Alignment of Low‐Valent Octanuclear Palladium Atoms

A linear tetraphosphine, meso‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) was used to synthesize linear octapalladium‐extended metal atom chains as discrete molecules of [Pd₈(μ‐dpmppm)₄](BF₄)₄ ( 1 ) and [Pd₈(μ‐dpmppm)₄L₂](BF₄)₄ (L=2,6‐xylyl isocyanide (XylNC; 2 ), acetonitrile ( 3 ), and N,N‐dimethylformamide (dmf; 4 )), which are stable in the solution states and show interesting temperature‐dependent photochemical properties in the near IR region. Variable temperature NMR studies demonstrated that at higher temperature T≈140 °C the Pd₈ chains were dissociated into Pd₄ fragments, which were thermodynamically self‐aligned to restore the Pd₈ chains at lower temperature T<60 °C. The coldspray ionization mass spectra suggested a possibility for further aggregation of the linear tetrapalladium units.     

Group 3 Metal Initiators with an [OSSO]‐Type Bis(phenolate) Ligand for the Stereoselective Polymerization of Lactide Monomers

A series of 1,ω‐dithiaalkanediyl‐bridged bis(phenols) of the general type [OSSO]H₂ with variable steric properties and various bridges were prepared. The stoichiometric reaction of the bis(phenols) 1,3‐dithiapropanediyl‐2,2′‐bis(4,6‐di‐tert‐butylphenol), 1,3‐dithiapropanediyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], rac‐2,3‐trans‐propanediyl‐1,4‐dithiabutanediyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], rac‐2,3‐trans‐butanediyl‐1,4‐dithiabutane diyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], rac‐2,3‐trans‐hexanediyl‐1,4‐dithiabutanediyl‐2,2′‐bis[4,6‐di(2‐phenyl‐2‐propyl)phenol], 1,3‐dithiapropanediyl‐2,2′‐bis[6‐(1‐methylcyclohexyl)‐4‐methylphenol] (C₁, R=1‐methylcyclohexyl), and 1,4‐dithiabutanediyl‐2,2′‐bis[6‐(1‐methylcyclohexyl)‐4‐methylphenol] with rare‐earth metal silylamido precursors [Ln{N(SiHMe₂)₂}₃(thf)_x] (Ln=Sc, x=1 or Ln=Y, x=2; thf=tetrahydrofuran) afforded the corresponding scandium and yttrium bis(phenolate) silylamido complexes [Ln(OSSO){N(SiHMe₂)₂}(thf)] in moderate to good yields. The monomeric nature of these complexes was shown by an X‐ray diffraction study of one of the yttrium complexes. The complexes efficiently initiated the ring‐opening polymerization of rac‐ and meso‐lactide to give heterotactic‐biased poly(rac‐lactides) and highly syndiotactic poly(meso‐lactides). Variation of the ligand backbone and the steric properties of the ortho substituents affected the level of tacticity in the polylactides.     

2,6‐Bis(1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)pyridine and its octahedral copper complex

In the tridentate ligand 2,6‐bis(1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)pyridine, C₂₃H₁₉N₇, both sets of triazole N atoms are anti with respect to the pyridine N atom, while in the copper complex aqua[2,6‐bis(1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)pyridine](pyridine)(tetrafluoroborato)copper(II) tetrafluoroborate, [Cu(BF₄)(C₅H₅N)(C₂₃H₁₉N₇)(H₂O)]BF₄, the triazole N atoms are in the syn–syn conformation. The coordination of the Cu^II atom is distorted octahedral. The ligand structure is stabilized through intermolecular C—H...N interactions, while the crystal structure of the Cu complex is stabilized through water‐ and BF₄‐mediated hydrogen bonds. Photoluminiscence studies of the ligand and complex show that the ligand is fluorescent due to triazole–pyridine conjugation, but that the fluorescence is quenched on complexation.     

Positional and compositional disorder in a ruthenium(II) piano‐stool complex

In (η⁶‐p‐cymene)(difluorophosphinato‐κO){2‐[(1H‐pyrazol‐1‐yl)methyl‐κN²]pyridine‐κN}ruthenium(II) 0.85‐hexafluorophosphate 0.15‐tetrafluoroborate, [Ru(PO₂F₂)(C₁₀H₁₄)(C₉H₉N₃)](PF₆)_0.85(BF₄)_0.15, (I), the [PO₂F₂]⁻ ligand exhibits positional disorder due to one F atom and one O atom sharing the same two positions related by a mirror reflection across the O—P—F plane. The correct composition of this coordinated anion was successfully determined to be [PO₂F₂]⁻ by refining the complex with various tetrahedral anions in which terminal atoms have similar atomic form factors. The noncoordinated counter‐ion is compositionally disordered between [PF₆]⁻ and [BF₄]⁻. The difficulty in determining the correct composition of this anion illustrates the importance of a crystallographer remaining impartial and open to encountering unexpected moieties in the process of elucidating a structure.     

A triangular palladium(II) supramolecular coordination complex based on 1,4‐bis(1H‐imidazol‐1‐yl)benzene and (2,2′‐bipyridyl)palladium(II) nitrate: synthesis and crystal structure

The self‐assembly of ditopic bis(1H‐imidazol‐1‐yl)benzene ligands ( L ^H) and the complex (2,2′‐bipyridyl‐κ²N,N′)bis(nitrato‐κO)palladium(II) affords the supramolecular coordination complex tris[μ‐bis(1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′]‐triangulo‐tris[(2,2′‐bipyridyl‐κ²N,N′)palladium(II)] hexakis(hexafluoridophosphate) acetonitrile heptasolvate, [Pd₃(C₁₀H₈N₂)₃(C₁₂H₁₀N₄)₃](PF₆)₆·7CH₃CN, 2 . The structure of 2 was characterized in acetonitrile‐d₃ by ¹H/¹³C NMR spectroscopy and a DOSY experiment. The trimeric nature of supramolecular coordination complex 2 in solution was ascertained by cold spray ionization mass spectrometry (CSI–MS) and confirmed in the solid state by X‐ray structure analysis. The asymmetric unit of 2 comprises the trimetallic Pd complex, six PF₆^? counter‐ions and seven acetonitrile solvent molecules. Moreover, there is one cavity within the unit cell which could contain diethyl ether solvent molecules, as suggested by the crystallization process. The packing is stabilized by weak inter‐ and intramolecular C—H…N and C—H…F interactions. Interestingly, the crystal structure displays two distinct conformations for the L ^H ligand (i.e. syn and anti), with an all‐syn‐[Pd] coordination mode. This result is in contrast to the solution behaviour, where multiple structures with syn/anti‐ L ^H and syn/anti‐[Pd] are a priori possible and expected to be in rapid equilibrium.     

Salicylaldoxime‐functionalized poly(ethylene glycol)‐bridged dicationic ionic liquid ([salox‐PEG1000‐DIL][BF4]) as a novel ligand for palladium‐catalyzed Suzuki–Miyaura reaction in water

Two novel salicylaldoxime‐functionalized poly(ethylene glycol)‐bridged dicationic ionic liquids ([salox‐PEG₁₀₀₀‐DIL][BF₄] and [salox‐PEG₁₀₀₀‐DIL][PF₆]) were prepared and characterized. [salox‐PEG₁₀₀₀‐DIL][BF₄] was found to be an efficient and recyclable ligand for palladium‐catalyzed Suzuki–Miyaura reaction in water. The catalytic system could be easily recovered and reused for at least five runs only with slight decrease in its activity. Copyright © 2013 John Wiley & Sons, Ltd.     

Metal‐Carbene‐Templated Photochemistry in Solution: A Universal Route towards Cyclobutane Derivatives

A series of dicarbene‐bridged metallacycles [Ag₂( 1 )₂](PF₆)₂, [Ag₂( 2 )₂](BF₄)₂, [Ag₂( 3 )₂](PF₆)₂, [Ag₂( 7 )₂](BF₄)₂, [Ag₂( 8 )₂](BF₄)₂ and [Ag₂( 11 )₂](PF₆)₂ were obtained in high yields via the reactions of 1,2,4‐triazole‐, 1,2,3‐triazole‐ and imidazo[1,5‐a]pyridine‐based ligands with Ag₂O in CH₃CN. The C=C double bonds in all of the newly synthesized metallacycles went through [2 + 2] photodimerization under UV irradiation condition (λ = 365 nm, T = 298 K) yielding the dinuclear rctt‐cyclobutane‐silver(I) complexes [Ag₂( 4 )](PF₆)₂, [Ag₂( 5 )](BF₄)₂, [Ag₂( 6 )](PF₆)₂, [Ag₂( 9 )](BF₄)₂, [Ag₂( 10 )](BF₄)₂ and [Ag₂( 12 )](PF₆)₂, respectively with quantitative yields. Treatment of the these cyclobutane‐bridged silver(I) complexes with NH₄Cl resulted in the exclusive formation of cyclobutane derivatives after removal of the silver(I) metal ions.