Palladium-catalyzed coupling of tetraphenylbismuth(V) derivatives with methyl acrylate

Tetraphenylbismuth(V) derivatives of the general formula Ph₄BiX [X = OSO₂C₆H₄Me-4, OC₆H₂(NO₂)₃-2,4,6, OC₆H₂(NO₂-4)(Br₂-2,6), OSO₂C₆H₃(OH)(COOH)] react with methyl acrylate in the presence of palladium dichloride (1:3:0.04 molar ratio) in acetonitrile at 20°C to form the cross-coupling products, methyl cinnamate (0.17–0.54 mol mol^?1 starting bismuth compound) and methylhydrocinnamate (0.10–0.73 mol mol^?1), diphenyl (0.06–0.80 mol mol^?1), and benzene (0.02–0.36 mol mol^?1). The highest C-phenylating activity is shown by Ph₄BiOSO₂C₆H₄Me-4. The mechanisms with the palladium-catalyzed cross-coupling reactions are suggested.     

Synthesis and structure of bismuth-containing complexes [(Ph4BiO)2{2,5-(CH3)2C6H3S(O)}] 2 + [Ph2Bi2I6]2−,[(Ph4Bi]+[PhBi(C5H5N)I3]−, [Ph4Sb] 4 + [Bi4I16]4−⋅2(CH3)2 C=O, and [Ph4Sb] 3 + [Bi5I18]3−

The reactions of tetraphenylbismuthonium and -stibonium salts Ph₄EX (E = Bi, Sb; X = I, OSO₂ (C₆H₃(CH₃)₂-2,5), OSO₂C₆H₃(OH-4)(COOH-3)) with bismuth triiodide in acetone afford complexes [Ph₄Bi]⁺[PhBi(C₅H₅N)I₃]^-, [(Ph₄BiO)₂S(O){2,5-(CH₃)₂C₆H₃S(O)} [Ph₂Bi₂I₆]^2–, [Ph₄Sb [Bi₄I₁₆]^4-·2(CH₃)²C=O, and [Ph₄Sb] ₃₊ ⁺ [Bi₅I₁₈]^3-, whose structural units, according to the X-ray diffraction data, are tetraphenylbismuthonium (-stibonium) cations and mono-, di-, tetra-, and pentanuclear anions, respectively.     

Competing reactions of hydrophenylation and phenylation in tetraphenylantimony chloride methyl acrylate palladium chloride system

A new catalytic reaction of the competing phenylation and hydrophenylation in air of methyl acrylate with tetraphenylantimony chloride in the presence of PdCl₂ (0.04 mol per 1 mol of organometallic compound) in acetonitrile at 50°C for 6 h was studied. The yields of methyl cynnamate and methyl hydrocynnamate were 0.73 and 0.27 mol mol^?1 respectively. The products ratio obtained depends slightly on the process duration, the Ph₄SbCl and methyl acrylate ratio, and the structure of Pd salt [PdCl₂, Pd(OAc)₂, Li₂PdCl₄], but significantly on the nature of a solvent (MeCN > DMF > THF). The use of Ph₄SbCl instead of Ph₄SbBr leads to decrease in the yield of methyl hydrocynnamate to 0.04 mol mol^?1. In the reactions of Ph₄SbX (X = F, I, OAc, O₂CEt) the product is not formed at all.     

Isoelectronic reagents. II. Standard formation enthalpies of phenyl and pfluorophenyl iodine dichlorides

The formation heats ΔH^o_fPhICl₂(c) = 21.7 kJ mol^?1 and ΔH^o_fpFC₆H₄ICl₂(c) = ?173.0 kJ mol^?1 were determined by reaction of iodides with excess chlorine in methyl cyanide. These heats are used to show:(i) that thermal or photo-decompositions of aryl iodine dichlorides are kinetically controlled,(ii) the greater halogenating ability of aryl iodine dichlorides than Ph₃ACl₂ (A = P, As, Sb) compounds, and(iii) the weakening of halogenating ability with phenylation.     

The kinetics of complex formation between Ti(IV) and hydrogen peroxide

The kinetics of the formation of the titanium‐peroxide [TiO²⁺₂] complex from the reaction of Ti(IV)OSO₄ with hydrogen peroxide and the hydrolysis of hydroxymethyl hydroperoxide (HMHP) were examined to determine whether Ti(IV)OSO₄ could be used to distinguish between hydrogen peroxide and HMHP in mixed solutions. Stopped‐flow analysis coupled to UV‐vis spectroscopy was used to examine the reaction kinetics at various temperatures. The molar absorptivity (ε) of the [TiO²⁺₂] complex was found to be 679.5 ± 20.8 L mol^?1 cm^?1 at 405 nm. The reaction between hydrogen peroxide and Ti(IV)OSO₄ was first order with respect to both Ti(IV)OSO₄ and H₂O₂ with a rate constant of 5.70 ± 0.18 × 10⁴ M^?1 s^?1 at 25°C, and an activation energy, E_a = 40.5 ± 1.9 kJ mol^?1. The rate constant for the hydrolysis of HMHP was 4.3 × 10^?3 s^?1 at pH 8.5. Since the rate of complex formation between Ti(IV)OSO₄ and hydrogen peroxide is much faster than the rate of hydrolysis of HMHP, the Ti(IV)OSO₄ reaction coupled to time‐dependent UV‐vis spectroscopic measurements can be used to distinguish between hydrogen peroxide and HMHP in solution. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 457–461, 2007     

Dephenylation of triphenylbismuth(v) and antimony(v) derivatives in a methyl acrylate—methanol system in the presence of copper and palladium salts

The influence of the central metal atom and acid residue in a molecule of organometallic compound Ph₃MX₂ (M = Bi, Sb; X = Cl, Br, OAc, O₂CEt) on the direction and yield of dephenylation products in a methyl acrylate— methanol system in the presence of Cu(OAc)₂ and Na₂PdCl₂(OAc)₂ was studied at 50 °C in acetonitrile. The main product of dephenylation of the antimony compounds is methyl cinnamate (yield 0.31–1.59 moles per mole of the starting Ph₃SbX₂), while anisole (0.55–0.97 mol) and halobenzene (0.67–1.04 mol) are those for compounds Ph₃Bi(O₂CR)₂ and Ph₃BiHal₂, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 655–658, April, 2006.     

Catalytic system based on triphenylantimony and tert-butyl hydroperoxide for the Heck reaction

Triphenylantimony was used as an efficient agent for C-phenylation of methyl acrylate in the presence of Bu^tOOH (1 to 2 mol) and a palladium salt (PdCl₂, Li₂PdCl₄; 0.04 mol) in AcOH at 50 °C. The yield of methyl cinnamate is two moles per mole of the starting Ph₃Sb.     

Reactions of tellurium(IV) chloride,aryl-, diaryl-, and triaryl tellurium(IV) chlorides with pyrimidine-2-thiols

1-Substituted 4,4,6-trimethyl-1H, 4H-pyrimidine-2-thiol(L), whose substituents are C₆H₅ ( 1 ), p-CH₃OC₆H₄ ( 2 ), p-O₂NC₆H₄ ( 3 ), n-C₄H₉ ( 4 ), and NH₂ ( 5 ), react with TeCl₄, ArTeCl₃ (Ar = C₆H₅, 4-CH₃OC₆H₄, or 4-C₂H₅OC₆H₄), Ph₂TeCl₂, and Ph₃TeCl, resulting in TeCl₃(L–H), ArTeCl₂(L–H), Ph₂TeCl₂.L, and Ph₃TeCl.L types of compounds. Elemental analyses, molecular weights, conductances in solutions, IR, and ¹H and ¹³C NMR spectral data of these compounds suggest that, in all of them, the pyrimidine-2-thiols ligate through sulfur only. In the first two types of derivatives, the thiol form of L reacts with tellurium moieties, resulting in the liberation of HCl. On the basis of these data TeCl₃(L-H) appears to exist as a dimer in which two Te atoms are probably 5-coordinated and are bridged by two Cl. Tellurium in ArTeCl₂(L-H), Ph₂TeCl₂.L, and Ph₃TeCl.L also appears to be 5-coordinated. IR data suggest that the Te–S bond in Ph₂TeCl₂.L is weak and, therefore, because of partial dissociation, the molecular complexes exhibit lower molecular weights in CH₃CN. Ph₃TeCl.L in acetonitrile behaves as a 1:1 electrolyte. Attempts to synthesize N-, S-, and Te-containing heterocycle ring compounds from TeCl₃( 1/2 -H) and ArTe( 1/2 -H)Cl₂ did not succeed.     

Anionic Gold(I) Complexes—Twelve‐ and Ten‐Vertex Monocarba‐closo‐borate Anions with Carbon–Gold σ Bonds

The anionic gold(I) complexes [1‐(Ph₃PAu)‐closo‐1‐CB₁₁H₁₁]^? ( 1 ), [1‐(Ph₃PAu)‐closo‐1‐CB₉H₉]^? ( 2 ), and [2‐(Ph₃PAu)‐closo‐2‐CB₉H₉]^? ( 3 ) with gold–carbon 2c–2e σ bonds have been prepared from [AuCl(PPh₃)] and the respective carba‐closo‐borate dianion. The anions have been isolated as their Cs⁺ salts and the corresponding [Et₄N]⁺ salts were obtained by salt metathesis reactions. The salt Cs‐ 3 isomerizes in the solid state and in solution at elevated temperatures to Cs‐ 2 with ΔH_iso=(?75±5) kJ mol^?1 (solid state) and ΔH^≠=(118±10) kJ mol^?1 (solution). The compounds were characterized by vibrational and multi‐NMR spectroscopies, mass spectrometry, elemental analysis, and differential scanning calorimetry. The crystal structures of [Et₄N]‐ 1 , [Et₄N]‐ 2 , and [Et₄N]‐ 3 were determined. The bonding parameters, NMR chemical shifts, and the isomerization enthalpy of Cs‐ 3 to Cs‐ 2 are compared to theoretical data.     

Synthesis and structure of 2,4,6-tribromophenoxytetraphenylbismuth

Four new complexes of pentavalent bismuth are synthesized: Ph₃Bi[OC₆H₂(Br₃-2,4,6)]₂, Ph₃Bi[OC₆H₂(Cl₃-2,4,6)]₂, Ph₄BiOC₆H₂(Br₃-2,4,6), and Ph₄BiOC₆H₂(Cl₃-2,4,6). Tetraphenylbismuth aroxides are produced by the disproportionation reaction of ligands from pentaphenylbismuth and triphenylbismuth diaroxides in toluene or from pentaphenylbismuth and phenol. Triphenylbismuth diaroxides are synthesized from phenol, triphenylbismuth, and hydrogen peroxide taken at a molar ratio of 2 : 1 : 1, respectively, in diethyl ether. According to the X-ray diffraction data, the bismuth atom surrounding in 2,4,6-tribromophenoxytetraphenylbismuth has the configuration of a trigonal bipyramid with the aroxyl ligand in the axial position. The Bi-C and Bi-O bond lengths are 2,184, 2.190, 2.234, and 2.514 Å, respectively, and the equatorial CSbC angles are equal to 111.4°, 121.3°, and 121.3°.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 935–938.Original Russian Text Copyright © 2004 by Sharutin, Egorova, Tsiplukhina, Gerasimenko, Pushilin.     

Heat of formation of Benzophenone Oxide

The heat of formation of benzophenone oxide, Ph₂CO₂, was measured using photoacoustic calorimetry. The enthalpy of the reaction Ph₂CN₂ + O₂ → Ph₂CO₂ + N₂ was found to be ?48.0 ±0.8 kcal mol^?1 and ΔH_f(Ph₂CN₂) was determined by measuring the reaction enthalpy for Ph₂CN₂ + EtOH → Ph₂CHOEt + N₂ (?53.6 ±1.0 kcal mol^?1). Taking ΔH_f(PhCHOEt) = ?10.6 kcal mol^?1 led to ΔH_f(Ph₂CN₂) = 99.2 ± 1.5 kcal mol^?1 and hence to ΔH_f(Ph₂CO₂) = 51.1 ± 2.0 kcal mol^?1. The results imply that the self-reaction of benzophenone oxide i.e., 2Ph₂CO₂ → 2Ph₂CO + O₂ is exothermic by ?76.0 ±4.0 kcal mol^?1.     

Synthesis,characterization, and acceptor behavior of dichlorotris(2-t-butylphenoxo)niobium(V)

The reaction of niobium pentachloride with three equivalents of 2-t-butylphenol in carbon tetrachloride afforded [NbCl₂(OC₆H₄C(CH₃)₃-2)₃]. The identity of the complex has been established by elemental analyses, molar conductance, molecular weight determination, IR, ¹H, and ¹³C-NMR and UV-Vis spectral studies. Based upon these studies, a square–pyramidal geometry around niobium has been proposed. Thermal behavior of the complex has been studied by TGA and DTA. Acceptor behavior of [NbCl₂(OC₆H₄C(CH₃)₃-2)₃] toward Ph₃P, Ph₃As, Ph₃PO, Ph₃AsO, and an uncommon ligand arsenictrithiophenoxide As(SPh)₃ allows the isolation of 1 : 1 addition compounds as shown by physicochemical, IR, and ¹H-NMR spectral studies. The formation of [NbCl₂(OC₆H₄C(CH₃)₃-2)₃] · As(SPh)₃ appears to be the first adduct of its class and suggests the suitability of As(SPh)₃ as a ligand.     

Kinetics of nucleophilic attack on coordinated organic moieties : XII. Addition of triphenylphosphine to [(C8H11)Co(C5H5)]BF4

A stopped-flow investigation of the reversible addition of Ph₃P to [(C₈H₁₁)Co(C₅H₅)]⁺ indicates the rate law, k_obs = k₁[Ph₃P] + k_?1. The low Δ2 of 21.0 ± 1.2 kJ mol^?1 and the negative ΔS2 of ?114 ± 5 J K^?1 mol^?1 are consistent with rapid addition to the enyl ligand. The higher Δ2 of 86.2 ± 5.1 kJ mol^?1 and the positive ΔS2 of +60 ± 17 J K^?1 mol^?1are as expected for the reverse dissociation. Preliminary studies show that the related complex [(C₇H₉)Co(C₅H₅)]⁺ is at least 65 times more electrophilic towards Ph₃P.     

Olefin polymerization and copolymerization by complexes bearing [ONNO]‐Type salan ligands: Effect of ligand structure and metal type (titanium,zirconium, and vanadium)

A series of novel titanium(IV) complexes bearing tetradentate [ONNO] salan type ligands: [Ti{2,2′‐(OC₆H₃‐5‐t‐Bu)₂‐NHRNH}Cl₂] (Lig¹TiCl₂: R = C₂H₄; Lig²TiCl₂: R = C₄H₈; Lig³TiCl₂: R = C₆H₁₂) and [Ti{2,2′‐(OC₆H₂‐3,5‐di‐t‐Bu)₂‐NHC₆H₁₂NH}Cl₂] (Lig⁴TiCl₂) were synthesized and used in the (co)polymerization of olefins. Vanadium and zirconium complexes: [ M{2,2′‐(OC₆H₃‐3,5‐di‐t‐Bu)₂‐NHC₆H₁₂NH}Cl₂] (Lig⁴VCl₂: M = V; Lig⁴ZrCl₂: M = Zr) were also synthesized for comparative investigations. All the complexes turned out active in 1‐octene polymerization after activation by MAO and/or Al(i‐Bu)₃/[Ph₃C][B(C₆F₅)₄]. The catalytic performance of titanium complexes was strictly dependent on their structures and it improves for the increasing length of the aliphatic linkage between nitrogen atoms (Lig¹TiCl₂ << Lig²TiCl₂ < Lig³TiCl₂) and declines after adding additional tert‐Bu group on the aromatic rings (Lig³TiCl₂ < Lig⁴TiCl₂). The activity of all titanium complexes in ethylene polymerization was moderate and the properties of polyethylene was dependent on the ligand structure, cocatalyst type, and reaction conditions. The Et₂AlCl‐activated complexes gave polymers with lover molecular weights and bimodal distribution, whereas ultra‐high molecular weight PE (up to 3588 kg mol^?1) and narrow MWD was formed for MAO as a cocatalyst. Vanadium complex yielded PE with the highest productivity (1925.3 kg mol_v^?1), with high molecular weight (1986 kg mol^?1) and with very narrow molecular weight distribution (1.5). Copolymerization tests showed that titanium complexes yielded ethylene/1‐octene copolymers, whereas vanadium catalysts produced product mixtures. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2111–2123     

Triphenyltin substituted benzoates: A spectroscopic study of structure in solution and solid phases

¹¹⁹Sn NMR and Mössbauer spectroscopic data have been recorded for 12 compounds of formula Ph₃SnO₂CC₆H₄X(X = H, Me-2, NH₂-2, NMe₂-2, Cl-2, Cl-3, Cl-4, OH-2, OH-4, SMe-4 or OMe-2) and Ph₃SnO₂CC₁₀H₇-1. On the basis of these measurements all the compounds are assigned a coordination number of four at tin in solution, and, with the exception of the Cl-2 and OH-2 derivatives, retain this structure in the solid. Both of these latter compounds exhibit enhanced Mössbauer quadrupole splittings (3.71 and 2.97 mm s⁻¹), which are attributed to carboxylate- and hydroxyl-bridged structures, respectively. The variable-temperature Mössbauer spectra of two compounds (X = OMe-2 or OH-2) are discussed.     

Organotin compounds bearing mesogenic sidechains: synthesis, X-ray structures and polymerisation chemistry

Organotin compounds R₃Sn(CH₂)_n+2OC₆H₄C₆H₄Y (R₃=Ph₃, Ph₂Bu; Y=H, CN; n=1-3) and RX₂Sn(CH₂)_n+2OC₆H₄C₆H₄Y (R=Ph, Bu; Y=H, CN; X=Br, I; n=1-3) have been synthesised and characterised by ¹H-, ¹³C-, ¹¹⁹Sn-NMR and Mössbauer spectroscopies. X-ray crystallography reveals tetrahedral geometries for Ph₃Sn(CH₂)₄OC₆H₄C₆H₅ and Ph₃Sn(CH₂)₃OC₆H₄C₆H₄CN, a six-coordinated, bromine-bridged dimeric structure for PhBr₂Sn(CH₂)₃OC₆H₄C₆H₅ containing a mer-Br₃C₂OSn coordination sphere about tin and a five-coordinated monomeric structure for PhBr₂Sn(CH₂)₃OC₆H₄C₆H₄CN. In all cases there is strong alignment of mesogenic groups in the solid-state but only PhBr₂Sn(CH₂)₃OC₆H₄C₆H₄CN shows any indication of liquid-crystal behaviour. Wurtz polymerisation of RBr₂Sn(CH₂)₅OC₆H₄C₆H₅ (R=Ph, Bu), both of which contain non-chelating ether functions, generated polystannanes (RR′Sn)_n with M_n 2.3×10⁵; M_w 3.0×10⁵; M_w/M_n 1.30 and M_n 1.3×10⁵; M_w 2.5×10⁵; M_w/M_n 1.96, respectively, while no polymer was obtained from chelated PhBr₂Sn(CH₂)₃OC₆H₄C₆H₅     

Isolation of a Three‐Coordinate Boron Cation with a Boron–Sulfur Double Bond

The reaction of the bulky bis(imidazolin‐2‐iminato) ligand precursor (1,2‐(L^MesNH)₂‐C₂H₄)[OTs]₂ ( 1 ²⁺ 2[OTs]^?; L^Mes=1,3‐dimesityl imidazolin‐2‐ylidene, OTs=p‐toluenesulfonate) with lithium borohydride yields the boronium dihydride cation (1,2‐(L^MesN)₂‐C₂H₄)BH₂[OTs] ( 2 ⁺ [OTs]^?)_. The boronium cation 2 ⁺ [OTs]^? reacts with elemental sulfur to give the thioxoborane salt (1,2‐(L^MesN)₂‐C₂H₄)BS[OTs] ( 3 ⁺ [OTs]^?). The hitherto unknown compounds 1 ²⁺ 2[OTs]^?, 2 ⁺ [OTs]^?, and 3 ⁺ [OTs]^? were fully characterized by spectroscopic methods and single‐crystal X‐ray diffraction. Moreover, DFT calculations were carried out to elucidate the bonding situation in 2 ⁺ and 3 ⁺. The theoretical, as well as crystallographic studies reveal that 3 ⁺ is the first example for a stable cationic complex of three‐coordinate boron that bears a B?S double bond.     

Kinetische und mechanistische untersuchungen von übergangsmetallkomplexreaktionen : II. Kinetik und mechanismus der reaktion von trans- bromo(tetracarbonyl)phenylcarbinwolfram mit tertiären arylphosphanen, -arsanen und -stibanen

The kinetics of the reaction of trans-bromo(tetracarbonyl)phenylcarbyne-tungsten (IIIb) with N = PPh₃, AsPh₃, SbPh₃, P(p-C₆H₄CH₃)₃, P(p-C₆H₄Cl)₃, P(p-C₆H₄F)₃, P(p-C₆H₄NMe₂)₃, Ph₂AsCH₂AsPh₂ and P(OPh)₃ have been studied in octane, n-butyl bromide, 1,1,2-trichloroethane and various other solvents. The formation of the monosubstituted carbyne complex follows a first-order rate law. The rates of reaction depend neither on the nature of the substitting nucleophile nor on its concentration. The rates decrease with increasing polarity of the solvent. Under high CO-pressure the substitution is partially reversible. The activation parameters are ΔH^≠ 98–108 kJ mol^?1 and ΔS^≠ 26–53 J K^?1 mol^?1. The results are discussed on the basis of a dissociative mechanism.     

Palladium-Catalyzed C-Phenylation of Methyl Acrylate with Triphenylbismuth Dicarboxylates

A new catalytic reaction of C-phenylation of methyl acrylate with bismuth derivatives Ph₃Bi(O₂CR)₂ (R = H, Me, Et, Bu, CF₃, Ph) or Ph₃BiCl₂ in a 3 : 1 ratio was studied. The reaction was performed in the presence of 4 mol % palladium compounds PdCl₂, Pd(OAc)₂, Pd₂(dba)₃, Pd(Ph₃P)₂Cl₂, and PdLCl₂ (L = dppm, dppe, dppp, dppb, dppf, binap, xantphos) at 50°C in CH₃CN, DMF, THF, or CH₂Cl₂ and gave methyl cinnamate (yield up to 85% based on the starting bismuth compound), diphenyl (up to 138%), and benzene (up to 59%).     

Interconversion of Molybdenum Imido and Amido Complexes by Proton‐Coupled Electron Transfer

Interconversion of the molybdenum amido [(^PhTpy)(PPh₂Me)₂Mo(NHtBuAr)][BArF²⁴] (^PhTpy=4′‐Ph‐2,2′,6′,2“‐terpyridine; tBuAr=4‐tert‐butyl‐C₆H₄; ArF²⁴=(C₆H₃‐3,5‐(CF₃)₂)₄) and imido [(^PhTpy)(PPh₂Me)₂Mo(NtBuAr)][BArF²⁴] complexes has been accomplished by proton‐coupled electron transfer. The 2,4,6‐tri‐tert‐butylphenoxyl radical was used as an oxidant and the non‐classical ammine complex [(^PhTpy)(PPh₂Me)₂Mo(NH₃)][BArF²⁴] as the reductant. The N?H bond dissociation free energy (BDFE) of the amido N?H bond formed and cleaved in the sequence was experimentally bracketed between 45.8 and 52.3 kcal mol^?1, in agreement with a DFT‐computed value of 48 kcal mol^?1. The N?H BDFE in combination with electrochemical data eliminate proton transfer as the first step in the N?H bond‐forming sequence and favor initial electron transfer or concerted pathways.