Radical polyaddition reaction of bis(α-trifluoromethyl-β,β-difluorovinyl) 2,3,5,6-tetrafluoroterephthalate

To develop the radical polyaddition of bisperfluoroisopropenyl esters to preparation of polymers bearing higher fluorine content, the polyaddition reactivity of bis(α-trifluoromethyl-β,β-difluorovinyl) 2,3,5,6-tetrafluoroterephthalate [CF₂C(CF₃)OCOC₆F₄COOC(CF₃)CF₂] (TFT) with 1,4-dioxane (DOX) and diethoxydimethylsilane (DEOMS) were described. The results of the model reactions of 2-pentafluorobenzoxypentafluoropropene [CF₂C(CF₃)OCOC₆F₅] (PFBP) with THF, DOX and DEOMS showed that the reactions took place almost quantitatively and the main products were mono-addition compound for THF and di-addition compounds for DOX and DEOMS, respectively. The polyaddition of TFT with DOX or DEOMS yielded corresponding polymers of about 1×10⁴ as a molecular weight bearing unimodal molecular weight distribution by the initiation of peroxides such as benzoyl peroxide and di-tert-butyl peroxide. TFT showed the slightly higher reactivity compared to that of non-fluorinated analogue, bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate (BFP), by the results of ternary polyaddition of TFT/BFP/DOX system. Polymers bearing TFT moiety showed the higher thermostability and contact angle.     

Direct reductive amination of carbonyl compounds using bis(triphenylphosphine) copper(I) tetrahydroborate

A direct reductive amination protocol for aldehydes/ketones using bis(triphenylphosphine) copper(I) tetrahydroborate as a novel reducing agent in the presence of sulfamic acid has been developed. The reagent chemoselectively reduces the imine moiety and does not affect other reducible functionalities such as chloro, nitro, cyano and methoxy.     

EPR and electronic spectral properties of aryl-substituted bis(dithiophosphato)copper(II) complexes

The spectral properties of bis(diaryl-dithiophosphato)copper(II) complexes, [Cu(S(2)P(OR)(2))(2)], with R = o-cresyl (complex I) and 2,6-dimethylphenyl (complex II) are studied by EPR- and vis spectroscopy. In solid (powder) state both complexes exhibit dark brown colour and are paramagnetic. Room temperature EPR spectra of the complexes dissolved in non-coordinating (C(6)H(5)CH(3), C(5)H(12), C(6)H(14)), acceptor (CHCl(3), CCl(4)) or donor (DMFA, DMSO) solvents have typical features of the chromophore CuS(4). In non-coordinating and acceptor solvents their isotropic EPR parameters are: g(iso)=2.047+/-0.003, (Cu)A(iso) = 7.2+/-0.1 mT and (P)A = 0.95+/-0.1 mT. An absorption band characterizes the vis spectra in these solvents with a maximum at 427 nm, due to a ligand-to-metal charge-transfer transition. One hour after dissolution the absorbance at 427 nm follows Beer's law with molar absorptivity (epsilon) about 11000, which does not change significantly after 24 h staying at room temperature or after 30 min heating at 50 degrees C. Both DMFA and DMSO exhibit specific solute-solvent interaction with the acceptor centre of copper complex yielding an axial adduct, with increased g-factor and decreased (hf)A compared to the initial complex. An additional EPR signal with unresolved hyperfine structure is also detected in DMSO. EPR and vis intensities of both bis(diaryl-dtp)Cu(II) complexes decrease after dissolution in both solvents. Moreover, they are EPR silent in pyridine and do not show any absorption in the vis spectra.     

Fluorinated phosphorus compounds: Part 6. The synthesis of bis(fluoroalkyl) phosphites and bis(fluoroalkyl) phosphorohalidates

Reaction of phosphorus trichloride with tert-butanol and fluoroalcohols gave bis(fluoroalkyl) phosphites (R_FO)₂P(O)H in 42-89% yield, where R_F=HCF₂CH₂, H(CF₂)₂CH₂, H(CF₂)₄CH₂, CF₃CH₂, C₂F₅CH₂, C₃F₇CH₂, (CF₃)₂CH, (FCH₂)₂CH, CF₃(CH₃)₂C, (CF₃)₂CH₃C, CF₃CH₂CH₂, C₄F₉CH₂CH₂ and C₆F₁₃CH₂CH₂. Treatment of these with chlorine in dichloromethane gave the bis(fluoroalkyl) phosphorochloridates (R_FO)₂P(O)Cl in 49-96% yield. The chloridate (CF₃CH₂O)₂P(O)Cl was isolated in much lower yield from the interaction of thionyl chloride with bis(trifluoroethyl) phosphite. Heating the latter in dichloromethane with potassium fluoride and a catalytic amount of trifluoroacetic acid gave the corresponding fluoridate (CF₃CH₂O)₂P(O)F in 84% yield. Treatment of bis(trifluoroethyl) phosphite with bromine or iodine gave the bromidate (CF₃CH₂O)₂P(O)Br and iodidate (CF₃CH₂O)₂P(O)I in 51 and 46% yield, respectively. The iodidate is the first dialkyl phosphoroiodidate to have been isolated and characterised properly—its discovery lags behind the first isolation of a dialkyl phosphorochloridate by over 130 years. The fluoroalkyl phosphoryl compounds are generally more stable than known unfluorinated counterparts.     

Solvent Effect on the Ligand Exchange between Bis(diethyldithiocarbamato)copper(II) and Bis(diethyldiselenocarbamato)copper(II)

EPR and spectrophotometric study on the products of ligand‐exchange taking place on mixing bis(diethyldiselenocarbamato)copper(II), [Cu(Et₂dsc)₂], and bis(diethyldithiocarbamato)copper(II), [Cu(Et₂dtc)₂], solutions is reported. EPR spectra monitored at room temperature for one month period reveal a stable equilibrium among the parents (chromophores CuS₄ and CuSe₄) and the obtained mixed‐chelate [Cu(Et₂dtc)(Et₂dsc)] complex (chromophore CuS₂Se₂) in heptane, hexane, benzene, toluene, acetone, DMFA, DMSO and dichloromethane. In CCl₄ and CHCl₃ two new additional EPR spectra appear attributed to the mixed‐chelate complexes with the chromophores CuSSe₃ and CuS₃Se which are not observed with electronic spectroscopy. The intensities of all five EPR spectra decrease with the time. It is assumed that the new mixed‐chelates observed in CCl₄ and CHCl₃ are obtained in a reaction of [Cu(Et₂dtc)(Et₂dsc)] or [Cu(Et₂dtc)₂] with the ester of diselenocarbamic acid which is formed in a parallel reaction of [Cu(dsc)₂]with CCl₄ or CHCl₃.     

EMR Study of Bis(benzene-dithiocarboxylato)copper(II) Complex in Solution and Magnetically Diluted in Different Host Lattices

EMR studies of bis(benzene-dithiocarboxylato)copper(II) in the form of the pure solid sample, in solution as well as magnetically diluted in the host lattices of the corresponding complexes of Ni^II, Zn^II, Pd^II, and Pt^II are reported. Two different samples (violet and blue) have been obtained in the Ni^II complex host lattice with EMR spectra indicating a superposition of several individual Cu^II signals. The EMR spectrum of the violet sample is explained by a superposition of the individual signals of (thio-, perthio-carboxylate)Cu^II and bis(perthiocarboxylate)Cu^II while that for the blue Cu/Ni(dtb)₂ complex, as well as for Cu/Pd (dtb)₂ is explained by different positions of the Cu^II species in the host lattices. The EMR spectrum typical for the magnetically diluted sample caused by self redox reaction has been recorded in the pure solid sample of copper(II) dithiocarboxylate complex.     

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.     

Syntheses, structures and magnetic properties of five iron(II) coordination polymers with flexible bis(imidazole) and bis(triazole) ligands

Five iron(II) coordination polymers, {[Fe(bte)₂(NCS)₂][Fe(bte)(H₂O)₂(NCS)₂]}_n (1), [Fe(bime)(NCS)₂]_n (2), [Fe(bime)(dca)₂]_n (3), [Fe(bime)₂(N₃)₂]_n (4) and [Fe(btb)₂(NCS)₂]_n (5), were synthesized using the flexible ligands 1,2-bis(1,2,4-triazol-1-yl)ethane (bte), 1,2-bis(imidazol-1-yl)ethane (bime) and 1,4-bis(1,2,4-triazol-1-yl)butane (btb), together with NCS⁻, dicyanamide (dca) and N₃⁻. The compound 1 contains two kinds of motifs (double chain and single chain) and forms a three-dimensional hydrogen bonded network; 2 and 3 contain one-dimensional triple chains; and 4 and 5 form two-dimensional (4, 4) networks. The coordination anions (NCS⁻, dca and N₃⁻) and the structural characteristics of the ligands (bte, bime and btb) play an important role in the assembly of the topologies. Magnetic studies reveal that 1-5 remain in the high-spin state over the whole temperature range 2-300 K and no detectable spin-crossover is observed.     

The first bis(phosphine) monoxide (BPMO) complexes of copper(I)

Copper(I) complexes of bis(phosphine) monoxide ligands, bis(diphenylphosphino)ethane monoxide (dppeo) and bis(diphenylphosphino)methane monoxide (dppmo) have been prepared and characterized. One of the complexes with dppeo was characterized by X-ray crystal structure analysis confirming Cu(I) coordination to hard and soft donors. The stability of these complexes in solution was probed via spectroscopic and electrochemical studies. Copper(I) is more readily oxidized in the presence of the hard O donor ligands. In solution, they readily exchange the hard donor O, for soft ligands. Although copper(I) prefers soft ligands and is more stable towards oxidation in their presence, it coordinates to hard donors when there is electrostatic or an entropy driven advantage.     

Fluorinated phosphorus compounds: Part 7. The reactions of bis(fluoroalkyl) phosphorochloridates with nitrogen nucleophiles

Forty bis(fluoroalkyl) phosphoramidates (R_FO)₂P(O)R were prepared in 10-91% yield by treating phosphorochloridates (R_FO)₂P(O)Cl where R_F was HCF₂CH₂, HCF₂CF₂CH₂, HCF₂CF₂CF₂CF₂CH₂, CF₃CH₂, C₂F₅CH₂, C₃F₇CH₂, (CF₃)₂CH, (FCH₂)₂CH and (CH₃)₂CF₃C with nucleophiles HR, where R was NH₂, NHMe, NMe₂, NHEt and NEt₂ in diethyl ether at 0-5 °C. The bulky chloridate [(CH₃)₂CF₃CO]₂P(O)Cl reacted with ammonia, methylamine, dimethylamine and ethylamine, but not with diethylamine—even on heating in the presence of 4-dimethylaminopyridine—due to steric hindrance at phosphorus. Fluorinated phosphoramidates have lower basicity and nucleophilicity than their unfluorinated counterparts: (EtO)₂P(O)NH₂ is more easily hydrolysed by HCl than (CF₃CH₂O)₂P(O)NH₂ and whereas, (EtO)₂P(O)NH₂ is known to react with oxalyl chloride and thionyl chloride to give (EtO)₂P(O)NCO and (EtO)₂P(O)NSO respectively, (CF₃CH₂O)₂P(O)NH₂ reacted only with oxalyl chloride to give (CF₃CH₂O)₂P(O)NCO in 10% yield. Two other new fluorinated species, (CF₃CH₂O)₂P(O)NHOMe and (CF₃CH₂O)₂P(O)N₃, were prepared by nucleophilic substitution of bis(trifluoroethyl) phosphorochloridate with methoxyamine and azide ion.     

Catalytic application of dinuclear palladium(II) bis(thiosemicarbazone) complex in the Mizoroki-Heck reaction

A convenient synthesis of new square planar dinuclear palladium(II) terephthaldehyde bis(thiosemicarbazone) complex has been described. The compositions of the complex have been established by elemental analysis, spectral methods and single crystal X-ray crystallographic technique. The new complex acts as an active recyclable homogeneous catalyst for the Mizoroki-Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl halides with various olefins under optimized conditions.     

Syntheses and structures of two copper coordination polymers with bis (1,2,4-triazol-1-ylmethyl)benzene and benzenedicarboxylate

Two copper coordination polymers [Cu(obtz)(bdc)] _n (1) and {[Cu(obtz)(phth)] · 2H₂O} _n (2) (obtz = 1,2-bis(1,2,4-triazol-1-ylmethyl)benzene, bdc = 1,3-benzenedicarboxylate, phth = 1,4-benzenedicarboxylate) were synthesized and characterized. Both 1 and 2 are 2-D networks constructed via the bridging ligands bdc and phth. The obtz ligands do not extend the dimension (2-D network) but add their thickness, 10.9 Å for 1 and 11.6 Å for 2. Complex 1 further constructs a 3-D network via π?π stacking interactions between the benzene rings of obtz ligands of adjacent 2-D networks. The thermal stabilities have been investigated.     

Synthesis of substituted bis(heteroaryl)maleimides

Substituted bis(fur-2-yl), bis(fur-3-yl) and bis(thien-2-yl) maleimides with potential antidiabetic properties are described. Their synthesis involves, as a key step, a Suzuki cross-coupling between various boron derivatives and the diiodomaleimides. Therefore, a wide range of substituted symmetric and non-symmetric maleimide derivatives can be prepared.     

Synthesis and characterization of sodium bis(trimethylstannyl) amide and bis(trimethylsilyl) bis(trimethylstannyl) -phospha-tetrazene

Sodium bis(trimethylstannyl)amide NaN(SnMe₃)₂, isolated by the reaction of trimethylstannyldiethylamine with sodium amide, reacts with tris(trimethylsilyl)hydrazino—dichloro-phosphine to form bis(trimethylsilyl)bis(trimethylstannyl)-2-phospha-2-tetrazene, (Me₃Si)₂N-N=P-N(SnMe₃)₂. Both the molecules have been isolated and characterized.     

Three-dimensional polymeric molecular pattern in the structure of a Ca(II) complex with pyrazine-2,3,5,6-tetracarboxylate and water ligands

Triclinic unit cell [space group P 1] of the calcium(II) complex with pyrazine-2,3,5,6-tetracarboxylate (2,3,5,6-PZTC) and water ligands [poly-bis(μ-aqua)di(μ-pyrazine-2,3,5,6-tetracarboxylate)tetracalcium(II)] contains four Ca(II) ions in two symmetry independent sites, two 2,3,5,6-PZTC ligands with their geometrical centers at the inversion centers at 0, 1/2, 1/2 and 0, 1/2, 0 and two coordinated water molecules. Metal ions are bridged by the ligand molecules via their N,O bonding moieties and carboxylate oxygen atoms as well as coordinated water oxygen atoms producing a densely packed three-dimensional molecular pattern. The Ca1 ion coordinates eight atoms at the corners of a distorted bicapped tetragonal bipyramid. The coordination number of the Ca2 ion is seven in a strongly distorted pentagonal bipyramid. The pyrazine ring planes of the ligands are parallel to each other forming molecular sheets stacked normal to the a axis. They are interconnected by carboxylate oxygen atoms coordinating calcium ions located between the adjacent sheets.     

Ion-pair chromatography of bis (sodium-sulfopropyl) disulfide brightener in acidic copper plating baths

Quantitative analysis of the brightener component bis (sodium-sulfopropyl) disulfide (SPS) in acidic copper plating baths poses a real challenge due to the complex chemical matrix containing large amounts of Cu(II) ion and sulfuric acid together with other organic additives and additive decomposition products. We developed a new ion-pair chromatography method to analyze micro-molar amounts of SPS directly in plating bath samples without the need for sample pre-treatment. Addition of tetra-N-methylammonium cation as ion-pairing agent to a methanol-sulfuric acid-water eluent increases the retention time of the anionic SPS2- on a C18 column sufficiently to separate this compound from Cu(II) ion and additive by-products.     

Photocatalytic degradation of chloroform by bis (bipyridine)dichlororuthenium(III/II)

Broadband (λ > 320 nm) irradiation of chloroform solutions of either [Ru(bpy)₂Cl₂] or [Ru(bpy)₂Cl₂]Cl exposed to air led to a photostationary state, in which [Ru(bpy)₂Cl₂]⁺ predominated, and to the continuous decomposition of CHCl₃, as evidenced by the accumulation of HCl, hydroperoxides (CCl₃OOH and CHCl₂OOH), and tetra-, penta-, and hexachloroethane. The addition of Cl^? increased the rate of photodecomposition, while the replacement of Cl^? by F^? greatly decreased the rate. The observations are consistent with a photocatalytic cycle in which [Ru(bpy)₂Cl₂]⁺ is photochemically reduced to [Ru(bpy)₂Cl₂], which is thermally reoxidized by CCl₃OO or CCl₃OOH. In the absence of air a much slower photodecomposition reaction takes place leading to continuously increasing concentrations of chloroethanes. The data are consistent with a catalytic cycle in which [Ru(bpy)₂Cl₂]⁺ is photoreduced, as in aerated solutions, while [Ru(bpy)₂Cl₂] is photooxidized with chloroform as the substrate.     

Rhodium(I) carbonyl complexes of mono selenium functionalized bis(diphenylphosphino)methane and bis(diphenylphosphino)amine chelating ligands and their catalytic carbonylation activity

The chelate complexes of the types (1) and (2) have been synthesized and characterized by IR and NMR spectroscopy. The lower shift of the ν(P-Se) bands and downfield shift of the ³¹P-{¹H}NMR signals for both P(III) and P(V) atoms in 1 and 2 compared to the corresponding free ligands indicate chelate formation through selenium donor. 1 and 2 show terminal ν(CO) bands at 1977 and 1981 cm⁻¹, respectively, suggesting high electron density at the metal center. The molecular structure of 2 has been determined by single-crystal X-ray diffraction. The rhodium atom is at the center of a square planar geometry having the phosphorus and selenium atoms of the chelating ligand at cis-position, one carbonyl group trans- to selenium and one chlorine atom trans- to phosphorus atom. 1 and 2 undergo oxidative addition (OA) reaction with CH₃I to produce acyl complexes (3) and (4), respectively. The kinetics of the OA reactions reveal that 1 undergoes faster reaction by about 4.5 times than 2. The catalytic activity of 1 and 2 in carbonylation of methanol was higher than that of the well known species [Rh(CO)₂I₂]⁻ and 2 shows higher catalytic activity compared to 1.