Mesogenic behaviour of two series of orthopalladated polar inline derivatives and their organic ligands (II)

Abstract

One series of 4-n-octyl-N-(4-X-benzylidene)anilines and two series of polar orthopalladated complexes derived from these of type Pd₂(μ-Y)₂ p-X-C₆H₃-CH = N-C₆H₄-C₈H_{17 2}; X: -H, -F, -Cl, -Br, -NO₂, -CN, -CH₃, -OCH₃, -CF₃, -COOCH₃, -OCOCH₃ and -OCOQH₅; Y: -OAc and -Cl; have been synthesized and their mesogenic properties studied. In the polar Schiff bases used as organic ligands, the polar end group determines both the presence of the mesophase and the type of mesophase exhibited. In the complexes, however, it is the central structure of the molecule that practically always determines mesogenic behaviour. No acetato-bridged complex is mesogenic. All the chloro-bridged complexes, however, show mesogenic behaviour. All these compounds show smectic A mesophases with the exception of the CN compound, which only exhibits a nematic mesophase.     

Regioselectivity in the amination of azines: Reaction of pyrazine derivatives with <Emphasis Type="Italic">O</Emphasis>-mesitylenesulfonylhydroxylamine

Treatment of 2-X-substituted pyrazines [X = H, Me, Et, Pr, i-Pr, t-Bu, MeCH(OH), H₂N, AcNH] with O-mesitylenesulfonylhydroxylamine gave the corresponding 2-X- and 3-X-(1-amino)pyrazin-1-ium mesitylenesulfonates. 2-Alkylpyrazines (X = Me, Et, Pr, i-Pr) displayed a correlation between the logarithms of the concentration ratio of 2- and 3-substituted cations and substituent steric constants. Wider series of substituted pyrazines [X = H, Me, Et, Pr, i-Pr, MeCH(OH), H₂N, AcNH] conformed to a multiparameter correlation between the logarithms of the concentration ratio of 2- and 3-substituted cations, on the one hand, and substituent constants σ_I, σ_R^o, and E _s^o, on the other. The obtained data on the regioselectivity of amination of pyrazines were interpreted in terms of DFT/PBE/3Z quantum-chemical calculations.     

Titanium complexes bearing aromatic-substituted β-enaminoketonato ligands: Syntheses, structure and olefin polymerization behavior

A series of titanium complexes [(Ar)NC(CF₃)CHC(R)O]₂TiCl₂ (4b: Ar = -C₆H₄OMe(p), R = Ph; 4c: Ar = -C₆H₄Me(p), R = Ph; 4d: Ar = -C₆H₄Me(o), R = Ph; 4e: Ar = α-Naphthyl, R = Ph; 4f: Ar = -C₆H₅, R = t-Bu; 4g: Ar = -C₆H₄OMe(p); R = t-Bu; 4h: Ar = -C₆H₄Me(p); R = t-Bu; 4i: Ar = -C₆H₄Me(o); R = t-Bu) has been synthesized and characterized. X-ray crystal structures reveal that complexes 4b, 4c and 4h adopt distorted octahedral geometry around the titanium center. With modified methylaluminoxane (MMAO) as a cocatalyst, complexes 4b-c and 4f-i are active catalysts for ethylene polymerization and ethylene/norbornene copolymerization, and produce high molecular weight polyethylenes and ethylene/norbornene alternating copolymers. In addition, the complex 4c/MMAO catalyst system exhibits the characteristics of a quasi-living copolymerization of ethylene and norbornene with narrow molecular weight distribution.     

Energies of optical excitations and ionization potentials for hydrocarbons with multiple bonds according to results of the DVM-Xα calculations

The electronic structure of the C₂H₂, C₂H₄, and trans-C₄H₆ molecules is calculated using the discrete variational X_α-method (DVM -X_α). The calculated energies of optical excitations and ionization potentials are compared with both experimental data and results of other nonempirical methods. We conclude that DVM -X_α is a reliable method for investigating the electronic structure of polyenes.     

Tridentate chelate π-bonded complexes of rhodium(I), iridium(I), and iridium(III) and chelate σ-bonded complexes of nickel(II), palladium(II), and platinum(II) formed by intramolecular hydrogen abstraction reactions

2,2′-Bis(o-diphenylphosphino)bibenzyl, o-Ph₂PC₆H₄CH₂CH₂C₆H₄PPh₂-o (bdpbz), is dehydrogenated by various rhodium complexes to give the planar rhodium(I) complex

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, from which the ligand, 2,2′-bis(o-diphenylphosphino)-trans-stilbene (bdpps) can be displaced by treatment with sodium cyanide. The stilbene forms stable chelate olefin complexes with planar rhodium(I) and iridium(I) and with octahedral iridium(III). On reaction with halide complexes of nickel(II), palladium(II) or platinum(II), the stilbene ligands

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(R = Ph or o-CH₃C₆H₄) lose a vinyl proton in the form of hydrogen chloride to give chelate, planar σ-vinyls of general formula =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; X = Cl, Br, I) of high thermal stability; analogous methyl derivatives =CHC₆H₄PR₂-o) are obtained from Pt(CH₃)₂(COD) (COD = 1,5-cyclooctadiene) and the stilbene ligands. The bibenzyl also forms chelate σ-benzyls HCH₂C₆H₄PPh₂-o) (M = Pd, Pt; X = Cl, Br, I). The ¹H NMR spectra of the o-tolyl methyl groups in the compounds =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; R = o-CH₃C₆H₄) vary with temperature, probably as a consequence of interconversion of enantiomers arising from restricted rotation about the M---P and M---C bonds. Possible mechanisms for the dehydrogenation reactions are briefly discussed.     

The Stability of Diphosphino-Boryl PBP Pincer Backbone: PBP to POP Ligand Hydrolysis

Since moisture may frequently be present in many solvents, it is important to know the reactivity of a catalyst against water for catalytic reactions. In order to explore the stability and understand the transformation process of diphosphino-boryl-based PBP pincer platform, [PdCl{B(NCH₂P^tBu₂)₂−o-C₆H₄}] ( 1 ) was treated with PdCl₂, HB(NCH₂PPh₂)₂−o-C₆H₄ was reacted with [PdCl₂(cod)] (cod=cyclo-octa-1,5-diene) and [Pd₂(dba)₃] (dba=dibenzylideneacetone), respectively, in the presence of water. Some novel palladium POP complexes, [Pd₂Cl₂(μ-Cl){μ-κ³-P,O,P−OB(NCH₂P^tBu₂)₂−o-C₆H₄}] ( 2 a ), [Pd₄(μ-Cl)₂(μ-O)₂{μ-κ³-P,O,P−OB(NCH₂PPh₂)₂−o-C₆H₄}₂] ( 2 b ), [Pd₂{μ-κ⁴-P,P,P,P−O(B(NCH₂PPh₂)₂−o-C₆H₄)₂}{μ-κ²-P,P−(NHCH₂PPh₂)₂−o-C₆H₄}] ( 3 ), were obtained. It was found that the PBP pincer backbone can easily be converted into a POP backbone in the presence of water. From the crystal structures of the resultant palladium complexes, possible pincer backbone transformation pathways were discussed.     

Design,Synthesis, and Properties of Substituted Polyacetylenes

This article reviews recent topics on the polymerization of substituted acetylenes, focusing on the synthesis of poly(diphenylacetylenes) and the living polymerization of phenylacetylenes. Diphenylacetylene (DPA) polymerizes with TaCl_s-n-Bu₄Sn to give a polymer which is thermally very stable but insoluble in any solvents. DPAs with various groups (e.g.,p-Me₃Si,m-Me₃Ge, p-t-Bu,and_p-PhO) polymerize similarly. These polymers are soluble and their M¯_w's reach 1 × 10⁶ to 3 × 10⁶. Some of them are more gas-permeable than poly(dimethylsiloxane). Several acetylenes (e.g., ClC -n-C₆H₁₃ and HCUC-t-Bu) have been found to undergo living polymerization with MoOCl₄-n-Bu₄Sn-EtOH. Whereas phenylacetylene (PA) does not polymerize in a living fashion, ortho-substituents in PA more or less suppress termination and chain transfer. PAs with bulky ortho groups (e.g., CF₃ and Me₃Ge) especially undergo virtually ideal living polymerization.     

Mass spectra of new heterocycles: X. Fragmentation of the molecular ions of 1-alkyl(cycloalkyl,aryl)-3-alkoxy(aryl)-2-methylsulfanyl-1<Emphasis Type="Italic">H</Emphasis>-pyrroles

The mass spectra of previously unknown 1-alkyl(cycloalkyl, aryl)-3-alkoxy(aryl)-2-methylsulfanyl-1H-pyrroles were studied. Fragmentation of all 3-alkoxy-substituted pyrroles under electron impact (70 eV) follow both ether and sulfide decomposition paths; In particular, 1-R-substituted 3-methoxy-2-methylsulfanyl-1H-pyrroles (R = Me, Et, i-Pr, s-Bu, cyclo-C₅H₉, cyclo-C₆H₁₁, Ph) lose methyl radical group from both methoxy and methylsulfanyl groups. The mass spectra of 1-sec-butyl- and 1-cycloalkylpyrroles also contained a strong peak (10–49%) from odd-electron [M — C _n H_2n ]^+· ion formed via cleavage of the N-R bond with synchronous hydrogen transfer. Cleavage of the O-Alk bond in the fragmentation of 3-alkoxy-1-isopropyl-2-methylsulfanyl-1H-pyrroles (Alk = Et, i-Pr, t-Bu) was accompanied by rearrangement process leading to the corresponding alkene and odd-electron 1-isopropyl-2-methylsulfanyl-1H-pyrrol-3-ol ion. The main fragmentation path of 1-alkyl-2-methylsulfanyl-3-phenyl-1H-pyrroles (Alk = Me, i-Pr) under electron impact involves dissociation of the S-Me bond with formation of rearrangement 1H-[1]benzothieno[2,3-b]pyrrol-8-ium ion.     

Palladium-catalysed synthesis of biaryl phosphines

Monodentate, biphenyl-type phosphines have emerged as a powerful class of ligands in homogeneous catalysis. Synthetic methods for these ligands are limited, however. We report that the palladium-catalysed Suzuki coupling of OPR₂(o-C₆H₄X) (R=Ph, t-Bu; X=Br, I) with arylboronic acids affords a variety of biaryl phosphine oxides including those that contain heterocycles. The corresponding phosphines are readily obtained by treatment with HSiCl₃. The methodology provides an easy entry to monodentate biaryl and heterobiaryl P^?X (X=N, O, S) phosphines with diverse steric and electronic properties.     

Novel Copolymers of Styrene and Some Ring-substituted 2-Phenyl-1,1-dicyanoethylenes

Novel copolymers of trisubstituted ethylene monomers, ring-substituted 2-phenyl-1,1-dicyanoethylenes, RC₆H₄CH = C(CN)2 (where R is 2-F, 2-CN, 3-CN, 4-CN, 3-C₆H₅O, 4-C₆H₅O, 2-C₆H₅CH₂O, 3-C₆H₅CH₂O, 4-C₆H₅CH₂O, 4-CH₃CO₂, 4-CH₃CONH, 4-(CH₃)₂N) and styrene were prepared by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r ₁) for the monomers is 4-(CH₃)₂N (3.35) > 4-C₆H₅CH₂O (3.1) > 2-C₆H₅CH₂O (1.77) > 3-C₆H₅CH₂O (1.72) > 4-C₆H₅O (1.70) > 4-CH₃CO₂ (1.58) > 2-F (1.11) > 3-C₆H₅O (0.90) > 3-CN (0.88) > 2-CN (0.86) > 4-CH₃CONH (0.84) > 4-CN (0.76). Relatively high T_g of the copolymers in comparison with that of polystyrene indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (1–10% wt), which then decomposed in the 500–800°C range.     

Synthesis and structural characterization of [(C5H4)SiMe2(N-t-Bu)]Ti[(o-C6H4)C(Ph)C(Ph)], generated via an alkyne-Ti benzyne coupling reaction

The thermolysis of [(C₅H₄)SiMe₂(N-t-Bu)]TiPh₂ in the presence of diphenylacetylene proceeds at 80 °C in cyclohexane solution with the sole formation of the titanacyclic complex [(C₅H₄)SiMe₂(N-t-Bu)]Ti[(o-C₆H₄)C(Ph)C(Ph)], which has been characterized by solution NMR measurements and X-ray crystallographic analysis. This reaction is accompanied by the elimination of benzene and presumably occurs via coupling of a titanium benzyne intermediate with diphenylacetylene. The two chemically inequivalent Ti-C bonds of 2.081(7) and 2.103(6) Å in [(C₅H₄)SiMe₂(N-t-Bu)]Ti[(o-C₆H₄)C(Ph)C(Ph)] reflect the increased electrophilicity of the d⁰ Ti(IV) center arising from the presence of the bifunctional ansa-cyclopentadienyldimethylsilylamido ligand.     

Novel Copolymers of Styrene. 3. Some Ring-Substituted Butyl 2-Cyano-3-Phenyl-2-Propenoates

Novel trisubstituted ethylenes, ring-substituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO₂C₄H₉ (where R is 2-C₆H₅CH₂O, 3-C₆H₅CH₂O, 4-C₆H₅CH₂O, 4-CH₃COO, 3-CH₃CO, 4-CH₃CO, 4-CH₃CONH, 2-CN, 3-CN, 4-CN, 4-(CH₃)₂N, 4-(C₂H₅)₂N) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and butyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r₁) for the monomers is 4-C₆H₅CH₂O (6.39) > 2-C₆H₅CH₂O (2.06) > 3-CH₃CO (1.86) > 3-C₆H₅CH₂O (1.78) > 4-CH₃COO (1.58) > 3-CN (1.47) > 4-CN (1.21) > 4-(C₂H₅)₂N (1.19) > 4-(CH₃)₂N (1.18) > 2-CN (1.04) > 4-CH₃CO (0.71) > 4-CH₃CONH (0.63). Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (3.6–9.5% wt), which then decomposed in the 500–800°C range.     

Structural diversity and versatility for organoaluminum complexes supported by mono- and di-anionic aminophenolate bidentate ligands

The present contribution describes the synthesis and structural characterization of structurally diverse organoaluminum species supported by variously substituted aminophenolate-type ligands: these Al complexes are all derived from the reaction of AlMe₃ with aminophenols 2-CH₂NH(R)-C₆H₃OH (1a, R = mesityl (Mes); 1b, R = 2,6-di-isopropylphenyl (Diip)) and 2-CH₂NH(R)-4,6-^tBu₂-C₆H₂OH (1c, R = Mes; 1d, R = Diip). The low temperature reaction of AlMe₃ with 1a–b readily affords the corresponding Al dimeric species [μ-η¹,η¹-N,O-{2-CH₂NH(R)-C₆H₄O}]₂Al₂Me₄ (2a–b), consisting of twelve-membered ring aluminacycles with two μ-η¹,η¹-N,O-aminophenolate units, as determined by X-ray crystallographic studies. Heating a toluene solution of 2a (80 °C, 3 h) affords the quantitative and direct formation of the dinuclear aluminium complex Al[η²-N; μ,η²-O-{2-CH₂N(Mes)-C₆H₄O}](AlMe₂) (4a) while species 2b, under the aforementioned conditions, affords the formation of the Al dimeric species [η²-N,O-{2-CH₂N(Dipp)-C₆H₄O}AlMe]₂ (3b), as deduced from X-ray crystallography for both 3b and 4a. In contrast, the reaction of bulky aminophenol pro-ligands 1c–d with AlMe₃ afford the corresponding monomeric Al aminophenolate chelate complexes η²-N,O-{2-CH₂NH(R)-4,6-^tBu₂-C₆H₂O}AlMe₂ (5c–d; R = Mes, Diip; Scheme 3) as confirmed by X-ray crystallographic analysis in the case of 5d. Subsequent heating of species 5c–d yields, via a methane elimination route, the corresponding Al-THF amido species η²-N,O-{2-CH₂N(R)-4,6-^tBu₂-C₆H₂O}Al(Me)(THF) (6c–d; R = Mes, Diip). Compounds 6c–6d, which are of the type {X₂}Al(R)(L) (L labile), may well be useful as novel well-defined Lewis acid species of potential use for various chemical transformations. Overall, the sterics of the aminophenol backbone and, to a lesser extent, the reaction conditions that are used for a given ligand/AlMe₃ set essentially govern the rather diverse “structural” outcome in these reactions, with a preference toward the formation of mononuclear Al species (i.e. species 5c–d and 6c–d) as the steric demand of the chelating N,O-ligand increases.     

Structural diversity and versatility for organoaluminum complexes supported by mono- and di-anionic aminophenolate bidentate ligands

The present contribution describes the synthesis and structural characterization of structurally diverse organoaluminum species supported by variously substituted aminophenolate-type ligands: these Al complexes are all derived from the reaction of AlMe₃ with aminophenols 2-CH₂NH(R)-C₆H₃OH (1a, R = mesityl (Mes); 1b, R = 2,6-di-isopropylphenyl (Diip)) and 2-CH₂NH(R)-4,6-^tBu₂-C₆H₂OH (1c, R = Mes; 1d, R = Diip). The low temperature reaction of AlMe₃ with 1a–b readily affords the corresponding Al dimeric species [μ-η¹,η¹-N,O-{2-CH₂NH(R)-C₆H₄O}]₂Al₂Me₄ (2a–b), consisting of twelve-membered ring aluminacycles with two μ-η¹,η¹-N,O-aminophenolate units, as determined by X-ray crystallographic studies. Heating a toluene solution of 2a (80 °C, 3 h) affords the quantitative and direct formation of the dinuclear aluminium complex Al[η²-N; μ,η²-O-{2-CH₂N(Mes)-C₆H₄O}](AlMe₂) (4a) while species 2b, under the aforementioned conditions, affords the formation of the Al dimeric species [η²-N,O-{2-CH₂N(Dipp)-C₆H₄O}AlMe]₂ (3b), as deduced from X-ray crystallography for both 3b and 4a. In contrast, the reaction of bulky aminophenol pro-ligands 1c–d with AlMe₃ afford the corresponding monomeric Al aminophenolate chelate complexes η²-N,O-{2-CH₂NH(R)-4,6-^tBu₂-C₆H₂O}AlMe₂ (5c–d; R = Mes, Diip; Scheme 3) as confirmed by X-ray crystallographic analysis in the case of 5d. Subsequent heating of species 5c–d yields, via a methane elimination route, the corresponding Al-THF amido species η²-N,O-{2-CH₂N(R)-4,6-^tBu₂-C₆H₂O}Al(Me)(THF) (6c–d; R = Mes, Diip). Compounds 6c–6d, which are of the type {X₂}Al(R)(L) (L labile), may well be useful as novel well-defined Lewis acid species of potential use for various chemical transformations. Overall, the sterics of the aminophenol backbone and, to a lesser extent, the reaction conditions that are used for a given ligand/AlMe₃ set essentially govern the rather diverse “structural” outcome in these reactions, with a preference toward the formation of mononuclear Al species (i.e. species 5c–d and 6c–d) as the steric demand of the chelating N,O-ligand increases.     

Tautomeric and Conformational Isomerism of Mercaptoacetylhydrazones of Methyl Alkyl Ketones

Mercaptoacetylhydrazones of methyl alkyl ketones (Alk = Me, Et, Pr, i-Pr, i-Bu, s-Bu, t-Bu) exist in solutions as a tautomeric mixture of linear and cyclic 1,3,4-thiadiazine forms.The linear hydrazone form exists as a set of conformers caused by restricted rotation of the amide group relative to the C–N bond. It is shown that tautomeric equilibrium constants correlate with the steric constants of the alkyl substituents, E_S.     

Novel Copolymers of Styrene. 2. Oxy Ring-Substituted 2-Cyano-3-phenyl 2-propenamides

Novel electrophilic trisubstituted ethylene monomers, oxy ring substituted 2-cyano-3-phenyl-2-propenamides, RC₆H₄CH? C(CN)CONH₂ (where R is 2-CH₃O, 3-CH₃O, 4-CH₃O, 2-C₂H₅O, 3-C₂H₅O, 4-C₂H₅O, 4-C₃H₇O, 4-C₄H₉O, 4-C₆H₁₃O, 3-C₆H₅O, 4-C₆H₅O, 3-C₆H₅CH₂O, 4-C₆H₅CH₂O), were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H- and ¹³C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, AIBN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H- and ¹³C-NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (0.2–1.2 wt%), which then decomposed in the 500–800°C range.     

11B NMR study of the tautomeric transformations of the 7,8-dicarba-nido-und ecaborane(11) adducts with pyridine derivatives

The tautomeric transformations of o-carborane(12) 7,8-C₂B₉H₁₁-Py(X), where Py(X) = 4-picoline (4-CH₃-C₅H₄N), 3-picoline (3-CH₃-C₅H₄N 4-stilbazole (4-C₆H_5-C₂H₂-C₅H₄N, or 3-bromopyridine (3-Br-C₅H₄N), and the iodo derivative 7,8-C₂B₉H₁₀I C₅H₅N were studied by¹¹B NMR spectroscopy in solution. The tautomeric transformations found are caused by migration of the bridging hydrogen cluster C₂B₉H₁₁ which is present in the structures. In the¹¹B NMR spectra, the boron signal is observed in the high-field region of the spectrum if the nearest two boron atoms are additionally bound by the bridging hydrogen. This enables the recording of the dynamic structural transformations of the adducts. It was found that the tautomeric equilibrium depends on the nature of substituents introduced in the heterocyclic ligand and the carborane cluster. Substituents with greater electron-accepting ability induce a shift of equilibrium toward the tautomer in which the bridging hydrogen is farther from the boron atom bonded to the substituent.     

Novel Copolymers of 4-Fluorostyrene. 10. Some Ring-substituted 2-Phenyl-1,1-dicyanoethylenes

Novel copolymers of trisubstituted ethylene monomers, ring-substituted 2-phenyl-1,1-dicyanoethylenes, RC₆H₂CH=C(CN)₂ (where R is 4-C₆H₅O, 2-C₆H₅CH₂O, 3,4-(C₆H₅CH₂O)₂, 2-C₆H₅CH₂O-3-CH₃O, 3-C₆H₅CH₂O-4-CH₃O, 2-Cl-6-NO₂, 4-Cl-3-NO₂, 5-Cl-2-NO₂) and 4-fluorostyrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r ₁) for the monomers is 3,4-(C₆H₅CH₂O)₂(31.0) > 2-C₆H₅CH₂O-3-CH₃O (24.8) > 3-C₆H₅CH₂O-4-CH₃O (15.2) > 4-C₆H₅O (3.1) > 4-Cl-3-NO₂ (1.9) > 2-Cl-6-NO₂ (1.6) > 5-Cl-2-NO₂ (1.5) > 2-C₆H₅CH₂O (1.4). High T_g of the copolymers, in comparison with that of poly(4-fluorostyrene) indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 270-400°C range with residue, which then decomposition in 400–800°C range.     

New dithio-bis-(diaroylmethanes) and acetyl diaroylchloromethyl disulfides: Attractive synthons and precursors for the liberation of highly reactive dithiiranes or thiosulfines

Summary In a new, feasible procedure five symmetricalpara-substituted diaroylmethanes ((4-X-C₆H₄-CO)₂-CH₂;X=F, Cl, Br, CH₃, and CH₃O) are prepared, in most cases in very good yields. For purification and activation, they are converted into the copper(II) complexes of their enolates. Subsequently, three reaction steps with disulfur dichloride (S₂Cl₂), chlorine, and ethanethioic acid yield new CH-acidic dithio-bis-(diaroylmethanes), -chlorosulfenic acid chlorides, and acetyl diaroyl-chloromethyl disulfides. The latter compounds are of interest for the liberation of highly reactive dithiirane/thiosulfine species. With thiomorpholine, -chlorosulfenic acid chlorides give -chlorosulfenic acid amides.

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Neue Dithio-bis-(diaroylmethane) und Acetyl-diaroylchlormethyl-disulfide: attraktive Synthone und Vorläufer zur Freisetzung hochreaktiver Dithiirane oder Thiosulfine

Zusammenfassung In einem neuen, gut handhabbaren Verfahren werden in meist sehr guter Ausbeute fünf symmetrischepara-substituierte Diaroylmethane ((4-X-C₆H₄-CO)₂-CH₂;X=F, Cl, Br, CH₃ und CH₃O) und daraus zur Reinigung und Aktivierung die Kupfer(II)komplexe ihrer Enolate dargestellt. Drei Reaktionsschritte mit Dischwefeldichlorid (S₂Cl₂), Chlor und Thioessigsäure führen der Reihe nach anschließend zu neuen CH-aciden Dithio-bis-(diaroylmethanen), -Chlorsulfensäure-chloriden und Acetyl-diaroylchlormethyl-disulfiden. Die letzteren Verbindungen sind zur Freisetzung von hochreaktiven Dithiiran/Thiosulfin-Spezies von Interesse. Mit Thiomorpholin geben -Chlorsulfensäurechloride -Chlorsulfensäureamide.

     

Triphenyltin Esters of N-(2-Carboxybenzylidene)anilines: Synthesis,Spectroscopic Characterization,X-ray Structure Analysis and Fungicidal Activity

Four triphenyltin carboxylates formulated as o- Ph₃SnOCOC₆H₄CH=N–Ar (Ar=C₆H₅; p -CH₃C₆H₄; o -CH₃C₆H₄; o -HOC₆H₄) were prepared and spectroscopically characterized. The crystal structure of o -Ph₃SnOCOC₆ H₄CH=NC₆H₅ indicates that the tin atom, in each of the two molecules comprising the asymmetric unit, exists in a distorted tetrahedral geometry owing to an intramolecular acyl O. . .Sn contact. These new triphenyltin carboxylates display marked toxicity against the fungus Ceratocystis ulmi .