Density functional study on the bromination of heteroelement-substituted acetylenes

The reactions of heteroelement-containing alkynes H₃SiC≡CH and R₃MC≡CPh [R₃M = H₃Si, Et₃Si, Et₃Ge, (MeO)₃Si, (EtO)₃Ge, N(CH₂CH₂O)₃Si, N(CH₂CH₂O)₃Ge, Bu₃Sn] with one and two bromine molecules were studied in terms of the density functional theory. Transition states along reaction channels leading to products of both addition at the triple bond (cis- and trans-dibromoalkenes and 1,1-dibromoalkenes) and cleavage of the M-C≡ bond were localized.     

Molybdenum and tungsten complexes with the heteroallyl-like Ph2P(O)C(S)NR− (R  Me,Ph) as ligand. X-ray structural analysis of Mo(CO)2(PPh3)(Ph2P(O)C(S)NPh)2 · CH2Cl2; A 4 : 3 piano-stool configuration

Ph₂P(O)C(S)N(H)R (R  Me, Ph) reacts with M(CO)₃(η⁵-C₅H₅)Cl (M  Mo, W) in the presence of Et₃N to give M(CO)₂(η⁵-C₅H₅)(Ph₂P(O)C(S)NR). The deprotonated ligand coordinates in a bidentate manner through N and S to give a four-membered ring system. M(CO)₃(PPh₃)₂Cl₂ (M  Mo, W) reacts with Ph₂P(O)C(S)N(H)R (R  Me, Ph) in the presence of Et₃N to give complexes in which the central metal atoms are seven coordinate through two ligands bonded via O and S to form five-membered ring systems, one PPh₃, and two CO groups. The complexes were characterised by elemental analyses, IR, ¹H NMR, and ³¹P NMR spectroscopy, and an X-ray structural analysis of Mo(CO)₂(PPh₃)(Ph₂P(O)C(S)NPh)₂ · CH₂Cl₂.     

1,4‐Addition of TMSCCl3 to Nitroalkenes: Efficient Reaction Conditions and Mechanistic Understanding

Improved synthetic conditions allow preparation of TMSCCl₃ in good yield (70 %) and excellent purity. Compounds of the type NBu₄X [X=Ph₃SiF₂ (TBAT), F (tetrabutylammonium fluoride, TBAF), OAc, Cl and Br] act as catalytic promoters for 1,4‐additions to a range of cyclic and acyclic nitroalkenes, in THF at 0–25 °C, typically in moderate to excellent yields (37–95 %). TBAT is the most effective promoter and bromide the least effective. Multinuclear NMR studies (¹H, ¹⁹F, ¹³C and ²⁹Si) under anaerobic conditions indicate that addition of TMSCCl₃ to TBAT (both 0.13 M ) at ?20 °C, in the absence of nitroalkene, leads immediately to mixtures of Me₃SiF, Ph₃SiF and NBu₄CCl₃. The latter is stable to at least 0 °C and does not add nitroalkene from ?20 to 0 °C, even after extended periods. Nitroalkene, in the presence of TMSCCl₃ (both 0.13 M at ?20 °C), when treated with TBAT, leads to immediate formation of the 1,4‐addition product, suggesting the reaction proceeds via a transient [Me₃Si(alkene)CCl₃] species, in which (alkene) indicates an Si???O coordinated nitroalkene. The anaerobic catalytic chain is propagated through the kinetic nitronate anion resulting from 1,4 CCl₃^? addition to the nitroalkene. This is demonstrated by the fact that isolated NBu₄[CH₂?NO₂] is an efficient promoter. Use of H₂C?CH(CH₂)₂CH?CHNO₂ in air affords radical‐derived bicyclic products arising from aerobic oxidation.     

From heterobimetallic transition metal complexes to linear coordination polymers based on cis‐ and trans‐L2Pt(CCPh)2

The reaction of cis‐(2,2′‐bipyridine) Pt(CCPh)₂ cis‐(4,4′‐dimethyl‐2,2′‐bipyridine) Pt‐(CCPh)₂ and trans‐(Ph₃P)₂Pt(CCPh)₂ towards different group 11 transition‐metal salts [M′X] (M′ = Cu, Ag; X = inorganic ligand) to give heterobimetallic or linear oligomeric and polymeric transition metal complexes is described. Different coordination modes for M′, PhCC, PPh₃, and X were found in these species. The structural aspects as well as the preference for one coordination mode over another is discussed. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:521–533, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10097     

Diastereoselective addition of organomanganese compounds to α-alkoxysubstituted propanals

Reactions of organomanganese compounds R¹MnI (R¹ = Ph, 4-MeC₆H₄-, Me, Bu,n-C₇H₁₅, BuC=C, PhOC), prepared from R¹Li and Mnl₂ in Et₂O, with aldehydes MeCH(OR²)CHO (R² = CH₂Ph, CH₂OMe, CH₂OCH₂Ph) affordthreo-alcohols MeCH(OR²)CH(OH)R¹ with high diastereoselectivity. The interactions of phenylmanganese derivatives PhMnX (X = Cl, Br, I), Ph₂Mn, and Ph₃MnLi with 2-benzyloxypropanal were used as examples for studying the influence of reagent and solvent nature on addition diastereoselectivity.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 178–181, January, 1993.     

Preparation of poly(aryleneethynylene)–type copolymers containing flexible linking methylene units. Optical properties of the copolymers suggesting occurrence of energy transfer between π–conjugated local units

Palladium–catalyzed polycondensation between 2,5–diiodo–3–hexylthiophene I–Th(Hex)–I with mixtures of p–diethynylbenzene HCC—Ph—CCH and α,ω–diethynylalkane HCC(CH₂)_lCCH (l = 3 or 8) gives poly(aryleneethynylene) PAE–type copolymers [CC(CH₂)_lCC—Th(Hex)]_m[CC—Ph—CC—Th(Hex)]_n containing the methylene unit. The copolymers have a molecular weight (M_n) of about 1.2 × 10⁴ as determined by GPC (polystyrene standard) and are considered to possess essentially a random sequences in view of the —CC(CH₂)_lCC— and —CC—Ph—CC— units as judged from their UV–visible spectra. By the incorporation of the (CH₂)_l unit, the λ_max position of the corresponding PAE homopolymer [CC—Ph—CC—Th(Hex)]_n is shifted to a shorter wavelength. However, the copolymers give rise to a photoluminescence PL peak essentially agreeing with a PL peak of the homopolymer, suggesting occurrence of energy transfer in the copolymer. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2201–2207, 1998     

Untersuchungen an Selen-Verbindungen. LXIX. Über das Reaktionsverhalten von Diphenylselendihalogeniden mit Ammoniak,Alkyl- und Silylaminen

Studies on Selenium Compounds. LXIX. On the Reactivity of Diphenyl Selenium Dihalides with Ammonia, Alkyl- and Silylamines The halides Ph₂SeX₂ (Ph = C₆H₅; X = Cl, Br) are reduced by NH₃, MeNH₂ and Me₂NH (Me = CH₃) at ?60°C forming Ph₂Se. The reaction of Ph₂SeCl₂ with Me₃SiNMe₂ yields Ph₂Se(NMe₂)Cl, whereas with (Me₃Si)₂NH the salt [Ph₂Se?N?SePh₂]Cl is formed. The infrared spectra are presented and discussed.     

Structural,Theoretical, and Spectroscopic Study of Mercury(II) Complexes of two New Unsymmetric Phosphorus Ylides

Abstract

The reaction of Ph₂PCH₂PPh₂ (dppm) with 4-methylphenacyl bromide and 2-(bromoacetyl)naphthalene in chloroform produce the new phosphonium salts [Ph₂PCH₂PPh₂CH₂C(O)C₆H₄Me]Br (1) and [Ph₂PCH₂PPh₂CH₂C(O)C₁₀H₇]Br (2). Further, by reaction of the monophosphonium salts of dppm with the strong base Et₃N the corresponding bidentate phosphorus ylides, Ph₂PCH₂P(Ph)₂ = C(H)C(O)C₆H₄Me (3) and Ph₂PCH₂P(Ph)₂ = C(H)C(O)C₁₀H₇ (4) were obtained. The reaction of these ligands with mercury(II) halides in dry methanol led to the formation of the mononuclear complexes {HgX ₂[(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄Me)]} [X = Cl (5), Br (6), and I (7)] and {HgX ₂[(Ph₂PCH₂PPh₂C(H)C(O)C₁₀H₇)]} [X = Cl (8), Br (9), and I (10)]. Characterization of the obtained compounds was performed by elemental analysis, IR, ¹H, ³¹P, and ¹³C NMR spectra. The structure of compounds 3 and 10 are unequivocally determined by single crystal X-ray diffraction techniques. X-ray analysis of 10 reveals the presence of mononuclear complex containing Hg atom in a distorted tetrahedral environment. In all complexes, the title ylides are coordinated through the ylidic carbon and the phosphine phosphorus. Computational studies on ligand 4 and complexes 8, 9, and 10 at DFT (B3LYP) level of theory are also reported. It was shown that the formation of P,C-coordinated 1+1 complex 10 is energetically more favored than corresponding P,P-coordinated 1+2 product.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the following free supplemental files: Additional figures]     

Mercury(II) complexes of new bidentate phosphorus ylides: synthesis,spectra and crystal structures

The reaction of dppm (1,1-bis(diphenylphosphino)methane) with 2-bromo-4-phenylacetophenone and benzyl bromoacetate in chloroform produces new phosphonium salts, [Ph₂PCH₂PPh₂CH₂C(O) C₆H₄Ph]Br (I) and [Ph₂PCH₂PPh₂CH₂COOCH₂Ph]Br (II). By allowing the phosphonium salts to react with the appropriate base, the bidentate phosphorus ylides, Ph₂PCH₂PPh₂=C(H)C(O)C₆H₄Ph (III) and Ph₂PCH₂PPh₂=C(H)C(O)OCH₂Ph (IV), were obtained. The reaction of these ligands with mercury(II) halides in dry methanol led to the formation of the mononuclear complexes {HgX₂[(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄Ph)]} (X = Cl (V); X = Br (VI); X = I (VII)) and {HgX₂[(Ph₂PCH₂PPh₂C(H)COOCH₂Ph)]} (X = Cl (VIII); X = Br (IX); X = I (X)). The FTIR and ¹H, ³¹P and ¹³C NMR spectra were studied. The structure of compound III was unequivocally determined by the single-crystal X-ray diffraction technique. Single-crystal X-ray analysis of the {HgBr₂[(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄Me)]} complex (XI) revealed the presence of a mononuclear complex containing the Hg atom in a distorted tetrahedral environment. In all complexes, the ylides referred to above were coordinated through the ylidic carbon and the phosphine atom.     

Determination of Spin-Spin Coupling Constants J(PP) on the Basis of 13C and 31p NMR Data

Abstract

The diphosphine dioxides Ph₂P (O) CH₂P (O)Ph₂.(I, Ph₂P(O)CH₂CH₂P(O)Ph₂ (II), Ph₂P(O)CH=CHP(O)Ph₂-cis (III), -trans (IV), [Ph₂P(O)] C=CH (V), [Ph₂P(O) 1₂C=PPh₃ (VI), and also non-symmetric Ph₂(P)OCH=CHP(O)PhEt-trans (VII), Et²P(O)CH=CHP(O)PhEt-trans (VIII), have been studied in CH²C1₂ and CHCl₃ solutions by means of ¹³C and ³¹P NMR.     

1,3-Migration of a phenyl group in the conversion of (Me3Si)2(PhMe2Si)CSiMePhX into (Me3Si)2(Ph2MeSi)CSiMe2Y species

The finding that compounds of the type (Me₃Si)₂(PhMe₂Si)CSiMePhX react with electrophiles to give very predominantly rearranged products (Me₃Si)₂(Ph₂MeSi)CSiMe₂Y, which would be expected to be thermodynamically disfavoured, can be rationalized in terms of a mechanism in which the anchimerically-assisted departure of X⁻ gives the Ph-bridged cation [(Me₃Si)₂

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MePh]⁺ which is attacked by the nucleophile at the less hindered centre bearing two Me groups rather than that bearing one Me and one Ph group, with the outcome determined by kinetic rather than thermodynamic factors. Both (Me₃Si)₂(Ph₂MeSi)CSiMe₂Br and its isomer (Me₃Si)₂(PhMe₂Si)CSiMePhBr react with AgBF₄ in CH₂Cl₂ or Et₂O to give >95% of the fluoride (Me₃Si)₂(Ph₂MeSi)CSiMe₂F. Reaction of the bromide (Me₃Si)₂(PhMe₂Si)CSiMePhBr with AgO₂CCF₃ in Et₂O, and that of the hydride (Me₃Si)₂(PhMe₂Si)CSiMePhH with ICl in CCl₄, likewise give >95% of the rearranged (Me₃Si)₂(Ph₂MeSi)CSiMe₂O₂CCF₃ and (Me₃Si)₂(Ph₂MeSi)CSiMe₂Cl, respectively.     

Die Kristallstruktur von (PPh4)2[Mo2(O2C?Ph)4Br2] · 2 CH2Br2

Crystal Structure of (PPh₄)₂[Mo₂(O₂C? Ph)₄Br₂] · 2 CH₂Br₂ The title compound, prepared by the reaction of Mo₂(O₂C? Ph)₄ with PPh₄Br and PPh₄N₃, respectively, under the assistance of CH₂Br₂, was characterized by an X-ray structure determination. Space group P2₁/n, Z = 2, R = 0.074 (5261 independent observed reflexions). The lattice dimensions are at ?70°C: a = 1562.9, b = 1406.2, c = 1662.1 pm, β = 94.11°. the compound consists of PPh₄^⊕ ions, CH₂Br₂ molecules, and centrosymmetric anions [Mo₂(O₂C? Ph)₄Br₂]^2?. The axis Br? Mo?Mo–Br is nearly linear (bond angle 175.6°) with bond lengths MoMo = 212.3 pm and Mo? Br = 303 pm, corresponding with a weak electrostatic Mo? Br bond. In the FIR spectrum the Mobr stretching vibration is found at 85 cm^?1, which corresponds with the low value of the force constant of 0.24 N · cm^?1.     

Spectral and crystallography studies of new palladacycle complexes with P,C‐ and C,C‐donor ligands; Application of (OAL16) to optimizing the yield of Mizoroki‐Heck reaction

The new symmetrical diphosphonium salt [Ph₂P(CH₂)₂PPh₂(CH₂C(O)C₆H₄Br)₂] Br₂ ( S ) was synthesized in the reaction of 1,2‐bis (diphenylphosphino) ethane (dppe) and related ketone. Further treatment with NEt₃ gave the symmetrical α‐keto stabilized diphosphine ylide [Ph₂P(CH₂)₂PPh₂(CHC(O)C₆H₄Br)₂] ( Y ¹ ). The unsymmetrical α‐keto stabilized diphosphine ylide [Ph₂P(CH₂)₂PPh₂(CHC(O)C₆H₄Br)] ( Y ² ) was synthesized in the reaction of diphosphine in 1:1 ratio with 2.3′‐dibromoacetophenone, then treatment with NEt_3. The reaction of dibromo (1,5‐cyclooctadiene)palladium (II), [PdBr₂(COD)] with this ligand ( Y ¹ ) in equimolar ratio gave the new C,C‐chelated [PdBr₂(Ph₂P(CH₂)₂PPh₂(C(H)C(O)C₆H₄Br)₂)] ( 1 ) and with unsymmetrical phosphorus ylide [Ph₂P(CH₂)₂PPh₂C(H)C(O)C₆H₄Br] ( Y ² ) gave the new P, C‐chelated palladacycle complex [PdBr₂(Ph₂P(CH₂)₂PPh₂C(H)C(O)Br)] ( 2 ). These compounds were characterized successfully by FT‐IR, NMR (¹H, ¹³C and ³¹P) spectroscopic methods and the crystal structure of Y ¹ and 2 were elucidated by single crystal X‐ray diffraction. The results indicated that the complex 1 was C, C‐chelated whereas complex 2 was P, C‐chelated. These air/moisture stable complexes were employed as efficient catalysts for the Mizoroki‐Heck cross‐coupling reaction of several aryl chlorides, and the Taguchi method was used to optimize the yield of Mizoroki‐Heck coupling. The optimum condition was found to be as followed: base; K₂CO₃, solvent; DMF and loading of catalyst; 0.005 mmol.     

Darstellung und Eigenschaften von Dibromotrachloro-u-methylen- diantimonaten(III) and Hexabromotetrachloro-u-methylen-diantimonaten(V)

Preparation and Properties of Dibromotetrachloro-u-methylene-diantimonates(III) and Hexabromotetrachloro-u-methylene-diantimonates(V) The complex salts (R₄E)₂ [Br₃Cl₂Sb]₂ CH₂ (R₄E = Et₄N, Ph₄P, Ph₄As, Ph₄Sb) are obtained by the reaction of [Cl₂Sb]₂ with R₄ EBr in dichloromethane. The oxidation of the new compounds with Br₂ at ?78°C, in dichloromethane, leads to the corresponding complex salts of pentavalent antimony (R₄E)₂[Br₃Cl₂Sb]₂CH₂.     

Phénylhalogénohydrodigermanes

The symmetric and unsymmetric phenylchlorohydrodigermanes can be isolated or characterized via partial halogenation of the Ge? H bonds of the symmetrical phenylhydrodigermanes Ph₂(H)GeGe(H)₂Ph, Ph(H)₂GeGe(H)₂Ph by chloromethyl methyl ether and carbontetrachloride. Some of these phenylchlorohydrodigermanes are formed by insertion of phenylchlorogermylene (PhGeCl) on the Ge? H or Ge? Cl bonds of the phenylchlorohydrogermanes. The hydrolysis of the monochloro phenylhydrodigermanes Ph₂(Cl)GeGe(H)₂ and Ph(Cl)(H)GeGe(H)₂Ph leads to the phenyl phenylhydrogermyl digermoxanes [Ph₂(H)GeGePh₂]₂O and [Ph(H)₂GeGe(H)Ph]₂O. Treatment of these oxides with the concentrated aqueous solutions of hydracides leads to the monofluorinated, brominated and iodinated phenylhydrodigermanes Ph₂(H)GeGe(X)Ph₂ and Ph(H)₂GeGe(H)(X)Ph (X) = F, Br, I). Phenylchlorohydrodigermanes decompose thermally by α-elimination on one germanium atom with formation of germylene and phenylchlorohydrogermane. The physico-chemical IR. and NMR. study of these phenylhalogenohydrodigermanes indicates that, if the vGe? H frequency variations are mostly linked to the inductive effects of the substituents on the same germanium, the variations of the chemical shifts of the Ge? H protons seem to be due to many factors and especially to the inductive effect of the substituents on the germanium and the magnetic anisotropy of the Ge? X bonds.     

Die Kristallstruktur von Ph3PNBr · Br2

Crystal Structure of Ph₃PNBr · Br₂ Ph₃PNBr · Br₂ ( 1 ) has been prepared besides of other products from the reaction of Ph₃PNH with bromine, forming orange‐yellow single crystals which are characterized by IR‐spectroscopy and by a crystal structure determination. Space group P2₁/n, Z = 4, lattice dimensions at 20 °C: a = 916.76(10), b = 1351.42(8), c = 1494.9(2) pm, β = 96.191(5)°, R₁ = 0.0538. 1 has a molecular structure in which the Br₂ molecule is coordinated at the nitrogen atom of the N‐bromine‐phosphoraneimine Ph₃PNBr in a linear arrangement N–Br–Br with bond lengths N–Br of 224.5(6) pm and Br–Br of 248.4(1) pm. The nitrogen atom of 1 is ψ‐tetrahedrally coordinated in addition by the phosphorus atom with a P–N distance of 165.3(6) pm and by the covalently bonded bromine atom with a bond length of 188.9(6) pm.     

Germanium-carbon versus germanium-nitrogen double-bond formation in the reactions between germylenes and diazo compounds

The reactions between methyl diazoacetate, HC(N₂)COOMe, and a range of germylenes L₂Ge [L = CH₃], NH₂, OCH₃, Ph, CH=CH₂, SiH₃, (H₃Si)₂N, and (H₃Si)₂CH] have been studied using MNDO calculations. Molecular and electronic structures have been determined for the transoid germaketimines L₂Ge=N-N=C(H)COOMe [the primary 11 adducts of L₂Ge and HC(N₂)COOMe], for their cyclic cisoid isomers, and for the germaethenes L₂Ge=C(H)COOMe. The intermediate L₂GeCH(N₂)COOMe was found to dissociate smoothly along the unique GeC bond when L = NH₂, OCH₃, or (H₃Si)₂N (so leading to no net reaction) but to undergo facile loss of N₂, forming the germaethene L₂Ge=C(H)COOMe, when L = CH₃, Ph, CH=CH₂, SiH₃, or (H₃Si)₂CH. The calculations thus enable the prediction of substantially different patterns of reactivity, and hence different products, in the reactions between diazo compounds and the two closely similar germylenes [(Me₃Si)₂N]₂Ge and [(Me₃Si)₂CH]₂Ge.     

Sulphur substituted organometallic compounds III. Reactions of Ph3SnCH2CH2SC6H4Me-p with some electrophilic reagents

Two distinct types of reactions of electrophiles, EN, with Ph₃SnCH₂CH₂SC₆H₄Me-p (I) have been established. Thus I₂ and HgCl₂ cleave the phenyltin bond: I + EN → Ph₂(N)SnCH₂CH₂SC₆H₄Me-p + PhE (E  I, N  I; E  HgCl, N  Cl) while from the reactions of Br₂ and MeI, as well as of ArSCl, as previously reported, ethylene is evolved: I + EN → Ph₃SnN + CH₂CH₂ + ESC₆H₄Me-p (E  Br, N  Br; E  Me, N  I)     

Bildung siliciumorganischer Verbindungen. XXXXIV. Synthese und Reaktionen Si-funktioneller 1, 3, 5, 7-Tetrasila-cyclo-octane

The synthesis of the HSi?resp. BrSi? containing 1,3,5,7-tetrasila-cyclooctanes (a) and (b) is described. (a) can be prepared from meH₂Si? CH₂? Sime₂? CH₂? SiHme? CH₂? Sime₂? CH₂Br resp. from meBrHSi? CH₂? Sime₂? CH₂? SiHme? CH₂? Sime₂? CH₂Br with Li and converted to (b) with Br₂. The siloxane (c) (m.p. 37–39°C) is formed by hydrolysis of (b) and also during the reaction of (b) with CH₂Br₂ and Li in (C₂H₅)₂O because of a cleavage of the ether.