Bis (2,4,6,8-cyclononatetraen-1-yl)methane

Bis (2,4,6,8-cyclononatetraen-1-yl)methanes Bis (2,4,6,8-cyclononatetraen-1-yl)methanes ( 2a–c ) have been prepared by reaction of all-cis-cyclononatetraenide with 1,1-dichlorodimethyl ether as well as with carbenium ion precursors 9b and 9c . The title compounds 2 are attractive precursors of highly delocalised nonafulvenes of type 3 ; however, elimination experiments 2→3 failed so far.     

Bis(oxazolinyl)phenyl transition metal complexes: synthesis, asymmetric catalysis, and coordination chemistry

Molecular catalysts for organic synthesis should be constructed to be tailored to target reactions and their desirable conditions. In our search for them, we have studied new types of transition metal molecular catalysts dressed with a tridentate N,C,N modular ligand, which consists of a C2-symmetric side-by-side phenyl group with chiral bis(oxazolinyl) substituents. The ligand, 2,6-bis(oxazolinyl)phenyl abbreviated as Phebox, can connect covalently to transition metals by the central carbon atom. Here, we review our recent work on the chemistry of Phebox and its metal complexes, including preparation, structural analysis, asymmetric Lewis acid catalysis, asymmetric hydrosilylation, asymmetric conjugate reduction, asymmetric reductive aldol reaction, and organometallic reactions.     

Aminophosphine ligands: synthesis,coordination chemistry,and activity of their palladium(II) complexes in Heck and Suzuki cross-coupling reactions

The reaction of 4-aminodiphenylamine or 2-aminofluorene with two equivalents of PPh₂Cl in the presence of Et₃N gives new bis(diphenylphosphino)amines N,N-bis(diphenylphosphino)-4-aminodiphenylamine 1 and N,N-bis(diphenylphosphino)-2-aminofluorene 2 in good yields. Oxidation of 1 or 2 with hydrogen peroxide, elemental sulfur or gray selenium affords the corresponding chalcogen derivatives. The palladium and platinum complexes of these P–N–P donor ligands were prepared by the reaction of the bis(phosphino)amines with MCl₂(cod) (M = Pd or Pt, cod = cycloocta-1,5-diene). All the new compounds have been characterized by analytical and spectroscopic methods, including ¹H-³¹P NMR, ¹H-¹³C HETCOR, or ¹H-¹H COSY correlation experiments. The Pd(II) complexes were investigated as catalysts in the Suzuki and Heck reactions; both showed good catalytic activity affording high yields of the desired products.     

微波作用下合成双(苯并咪唑-2-基)甲烷衍生物

在无溶剂、无催化剂存在条件下, 用微波促进5-取代-1H-苯并咪唑-2-乙酸乙酯和4-取代-1,2-邻苯二胺反应, 合成了取代双(苯并咪唑-2-基)甲烷衍生物, 产率均在80%以上. 产物结构经IR, ¹H NMR, MS等进行了表征.     

Ruthenium(II), copper(I) and silver(I) complexes of large bite bisphosphinite, bis(2-diphenylphosphinoxynaphthalen-1-yl)methane: Application of Ru(II) complexes towards the hydrogenation of styrene and phenylacetylene

Ruthenium(II), copper(I) and silver(I) complexes of large bite bisphosphinite Ph₂P{(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)}PPh₂ (1) are described. Reactions of bisphosphinite 1 with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ and RuCl₂(PPh₃)₃ afford mono- and bis-chelate complexes [RuCl(η⁶-p-cymene){η²-Ph₂P{(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)}PPh₂-κP,κP}]Cl (2) and trans-[RuCl₂{η²-Ph₂P{(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)}PPh₂-κP,κP}₂] (3), respectively. Treatment of 1 with CuX (X = Cl, Br and I) furnish 10-membered chelate complexes of the type [Cu(X){η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}] (4, X = Cl; 5, X = Br; 6, X = I), whereas [Cu(MeCN)₄]PF₆ affords a bis-chelated cationic complex [Cu{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}₂][PF₆] (7). Reaction between 1 and AgOTf produce both mono- and bis-chelated complexes [Ag{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}(SO₃CF₃)] (8) and [Ag{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}₂][SO₃CF₃] (9), respectively; whereas the similar reaction of 1 with[Ag(OTf)PPh₃] affords chelate complex of the type [Ag{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}(PPh₃)(SO₃CF₃)] (10). All the complexes were characterized by ¹H NMR, ³¹P NMR, elemental analysis and mass spectrometry, including low-temperature NMR studies in the case of silver complexes. The molecular structures of 4 and 6 are determined by X-ray diffraction studies. Ruthenium complexes 2 and 3 promote catalytic hydrogenation of styrene and phenylacetylene with good turnover numbers.     

Redox-active p-quinone-based Bis(pyrazol-1-yl)methane ligands: synthesis and coordination behaviour

The synthesis, structural characterisation and coordination behaviour of mono- and ditopic p-hydroquinone-based bis(pyrazol-1-yl)methane ligands is described (i.e., 2-(pz2CH)C6H3(OH)2 (2a), 2-(pz2CH)-6-(tBu)C6H2(OH)2 (2b), 2-(pz2CH)-6-(tBu)C6H2(OSiiPr3)(OH) (2c), 2,5-(pz2CH)2C6H2(OH)2 (4)). Ligands 2a, 2b and 4 can be oxidised to their p-benzoquinone state on a preparative scale (2a ox, 2b ox, 4 ox). An octahedral Ni II complex [trans-Ni(2c)2] and square-planar Pd II complexes [Pd2bCl2] and [Pd2b ox Cl2] have been prepared. In the two Pd II species, the ligands are coordinated only through their pyrazolyl rings. The fact that [Pd2bC12] and [Pd2b oxC12] are isolable compounds proves that redox transitions involving the p-quinone substituent are fully reversible. In [Pd2b oxCl2], the methine proton is highly acidic and can be abstracted with bases as weak as NEt(3). The resulting anion dimerises to give a dinuclear macrocyclic Pd II complex, which has been structurally characterised. The methylated ligand 2-(pz2CMe)C6H3O2 (11 ox) and its Pd II complex [Pd11 oxCl2] are base-stable. A new class of redox-active ligands is now available with the potential for applications both in catalysis and in materials science.     

Pentafluorophenyl imidato palladium(II) complexes: catalysts for Suzuki cross-coupling reactions

Novel N-bonded imidato complexes of general formula [Pd(N-N)(C6F5)(imidate)](imidate = maleimidate, succinimidate or phthalimidate; N-N = 2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me2bipy) or N,N,N',N'-tetramethylethylenediamine (tmeda)), [NBu4][Pd(C6F5)(H2O)(succinimidate)2] and [NBu4][Pd(C6F5)(L)(succinimidate)2](L = PPh3 or t-BuNC) have been synthesised. These complexes are air-, light- and moisture-stable. The crystal structures of [Pd(tmeda)(C6F5)(maleimidate)].H2O.0.5CHCl3, [NBu4][Pd(C6F5)(H2O)(succinimidate)2].H2O and [NBu4][Pd(C6F5)(t-BuNC)(succinimidate)2].2H2O have been determined by X-ray diffraction. Many of these new complexes are shown to be active phosphine-free palladium catalysts/precatalysts for the Suzuki cross-coupling reactions of aryl bromides and aryl chlorides with phenylboronic acid.     

Synthesis and antimicrobial evaluation of substituted (1,1'-biphenyl)-4-yl(3-methylbenzofuran-2-yl)methanones by Suzuki cross-coupling reaction

Russian Journal of General Chemistry - A series of new substituted [1,1'-biphenyl]-4-yl(3-methylbenzofuran-2-yl)methanones was prepared by Suzuki cross-coupling from...     

Mesoporous silicabis(ethylsulfanyl)propane palladium catalysts for hydrogenation and one-pot two-step Suzuki cross-coupling followed by hydrogenation

The solid phase catalytic activity of mesoporous silicabis(ethylsulfanyl)propane palladium catalysts for hydrogenation and novel one-pot two-step Suzuki cross-coupling followed by hydrogenation is described. The efficiency of catalytic hydrogenation was measured for substrate nitrobenzene with 5, 7 and 14 nm average pore diameter materials. The 5 nm pore material performed best and was also very effective in the catalytic hydrogenation of alkene, nitrile and imine substrates. Novel one-pot two-step Suzuki cross-coupling and hydrogenation was demonstrated using bromonitro- and bromodinitrobenzene and phenylboronic acid as substrates with conversion to the corresponding coupled amino compounds. As a consequence of the high affinity of the sulfur ligands for palladium, none was detected in leaching tests and the catalyst is easily separated and recycled.     

Dinuclear Pentacarbonyl Tungsten Complex Bridged by Bis（3,5-dimethylpyrazol- 1- yl ） methane

IntroductionPoly(pyrazol 1 yl)alkanes,especiallybis(pyrazol 1 yl)alkanes ,havebeenoneofpopularpolydentatenitrogendonorligandssinceTrofimenko’sfirstreport1andJulia’slatermodification .2 Ithasbeenfoundthatthecoordinationbehavioroftheseligandscaneasilybeadjustedbychang ingtheelectronicandstericcharacteristicsofsubstituentsonthepyrazolering .Recentinvestigationshavealsoshownthatthecentralcarbonatomoftheseligandscanbemodifiedbythevariousfunctionalgroupstoformversatileheteroscorpionateligands ,wh…     

Oxovanadium(IV) Complex with 1-Hydroxyethane-1,1-Diphosphonic Acid and Bis(2-pyridyl-1,2,4-Triazol-3-yl)methane

Russian Journal of Coordination Chemistry - The synthesis of oxovanadium(IV) complex with 1-hydroxyethane-1,1-diphosphonic acid (H4EDP) anion and bis(2-pyridyl-1,2,4-triazol-3-yl)methane (H2L) is...     

Recycling of homogeneous Pd catalysts using superparamagnetic nanoparticles as novel soluble supports for Suzuki, Heck, and Sonogashira cross-coupling reactions

Recycling of homogeneous catalysts could be achieved by using magnetic nanoparticles and solid-phase beads, but nanoparticle-supported catalysis proceeded much faster than its counterpart on resins.     

Efficient synthesis and Suzuki cross-coupling reactions of meso-tetrakis(2,6-dimethyl-4-triflyloxyphenyl)porphyrin

An ortho-dimethyl substituted meso-tetrakisarylporphyrin prefunctionalized with triflate groups was prepared in good yield from an accessible 2,6-dimethyl-4-(triflyloxy)benzaldehyde. This porphyrin is an interesting building block, which could directly be engaged in Suzuki cross-coupling reactions, to be further tetra functionalized with 3-pyridyl ligands in yields equal or above 85%. The porphyrin core of the various compounds bearing four remote coordination sites was metalated with zinc(II). The molecular structures of the starting triflate porphyrin derivative and of the zinc(II) porphyrin substituted with four 3-pyridyl groups bearing a protected alcohol were determined using X-ray crystallography.     

Copper coordination complexes of bis(4-(pyridin-2-yl)pyrimidin-2-ylthio)methane with in situ metal redox reactions

Five copper coordination complexes 1–5 with 2-bppm (2-bppm?=?bis(4-(pyridin-2-yl)pyrimidin-2-ylthio)methane) have been prepared and structurally elucidated. Complexes 1 and 2 are both discrete dinuclear [2?+?2] macrocyclic structures, simultaneously formed in one-pot reaction with Cu(NO₃)₂ with in situ reduction of Cu²⁺. Similarly, dinuclear [2?+?2] macrocyclic motifs are found with 3 and 4, which are also obtained by one-pot reaction but with CuCl accompanied by in situ air oxidation of Cu⁺. Compound 5 exhibits a 1-D chain structure with 2-bppm and Cu₂I₂ connected one by one. Luminescence is measured for 2, 4, and 5, all based on d¹⁰-closed shell Cu(I).     

Cationic palladium(II) complexes of ferrocenylphosphines as homogeneous hydrogenation catalysts for olefins

Cationic palladium(II) complexes of ferrocenylphosphines [(L-L′)Pd(S)₂][ClO₄]₂ ((L-L′) = Fe(η⁵-C₅H₄P (C₆H₅)₂)₂ 1, or Fe(η⁵-C₅H₅)(η⁵C₅H₃(CHMeNMe₂)P(C₆H₅)₂-1,2) 2a: S=pyridine or dimethylformamide) were prepared and characterized. The derivatives of 2a are effective catalysts for the hydrogenation of simple olefins at 30°C (1 atm H₂). The rate of reduction of styrene depends on the substrate concentration, catalyst concentration and the solvent, and is only slightly inhibited (16%) by the addition of mercury. These observations are conistent with a homogeneous catalytic system.     

Syntheses,crystal structures and properties of two cadmium coordination polymers containing bis (2-methylimidazol-1-yl)methane(2-mBIM) and bis (imidazol-1-yl)methane (BIM) ligands

Coordination polymers, {[Cd(2-mBIM)₃](ClO₄)₂} _n (1) and [Cd(BIM)₂(NO₃)₂] _n (2), have been prepared from the reaction of bis(2-methylimidazol-1-yl)methane(2-mBIM) with Cd(ClO₄)₂ and bis(imidazol-1-yl)methane (BIM) with Cd(NO₃)₂ in ethanol and water, respectively. Their structures were characterized by single crystal X-ray diffraction and IR spectroscopy. Compound 1 crystallizes in the rhombohedral space group R-3c with a = b = 12.3617(5) Å, c = 38.896(3) Å, γ = 120°, V = 5147.5(5) ų, z = 6. The Cd^II occupies a crystallographic inversion center and is coordinated by six N atoms from six distinct 2-mBIM ligands to form a slightly distorted octahedral geometry. Each 2-mBIM is coordinated to two Cd^II cations, linking alternatively four Cd^II cations, resulting in a 32-membered M₄L₄ macrometallacycle. Compound 2 crystallizes in the monoclinic space group C2/m with a = 14.400(3) Å, b = 9.3894(18) Å, c = 8.6926(17) Å, β = 123.499(2)°, V = 980.1(3) ų, z = 2. The Cd coordinates to four nitrogen atoms from four different BIM and two nitrates to form a slightly distorted octahedral geometry. The BIM ligands bridge to form a 1-D infinite double-bridged chain structure with 16-membered M₂L₂ macrometallacyclic structural units.