Summary: A tandem catalytic system, composed of (η5‐C5H4CMe2C6H5)TiCl3 ( 1 )/MMAO (modified methyl aluminoxane) and [(η5‐C5Me4)SiMe2(tBuN)]TiCl2 ( 2 )/MMAO, was applied for the synthesis of ethylene–hex‐1‐ene copolymers with ethylene as the only monomer stock. During the reaction, 1 /MMAO trimerized ethylene to hex‐1‐ene, while 2 /MMAO copolymerized ethylene with the in situ produced hex‐1‐ene to poly(ethylene–hex‐1‐ene). By changing the catalyst ratio and reaction conditions, a series of copolymer grades with different hex‐1‐ene fractions at high purity were effectively produced.
The overall strategy of the tandem 1 / 2 /MMAO catalytic system. 相似文献
Treatment of the osmium complex [Os{CHC‐(PPh3)CH(OH)‐η2‐C≡CH}(PPh3)2(NCS)2] ( 1 ) with excess triethylamine produces the first m‐metallaphenol complex [Os{CHC(PPh3)CHC(OH)CH}(PPh3)2(NCS)2] ( 2 ). The NMR spectroscopic and structural data as well as the nucleus‐independent chemical‐shift (NICS) values suggest that osmaphenol 2 has aromatic character. The reactivity studies demonstrate that 2 can react with different isocyanates to form the annulation reaction products [Os{CHC(PPh3)CHC(O?C?ONR)C}(PPh3)2(NCS)2] (R=Ph ( 3 ), iPr ( 7 ), Bn ( 8 )) via the carbamate intermediates [Os{CHC(PPh3)CHC(O‐C?ONHR)CH}(PPh3)2(NCS)2] (R=Ph ( 4 ), iPr ( 5 ), Bn ( 6 )). In addition, the similar annulation reactions can be extended to other unsaturated compounds containing N–C multiple bonds, for example, isothiocyanates, pyridine, and sodium thiocyanate, which can produce the corresponding fused osmabenzene complexes. In contrast, the reactions of 2 with common electrophiles, such as NOBF4, NO2BF4, N‐bromosuccinimide, and N‐chlorosuccinimide only led to the decomposition of the metallaphenol ring. The experimental results suggest that 2 is very electrophilic and readily reacts with nucleophiles, which is mainly due to the metal center and the strong electron‐withdrawing phosphonium group. 相似文献
Structure and magnetic properties of N‐diisopropoxyphosphorylthiobenzamide PhC(S)‐N(H)‐P(O)(OiPr)2 ( HLI ) and N‐diisopropoxyphosphoryl‐N′‐phenylthiocarbamide PhN(H)‐C(S)‐N(H)‐P(O)(OiPr)2 ( HLII ) complexes with the CoII cation of formulas [Co{PhC(S)‐N‐P(O)(OiPr)2}2] ( 1 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)2}2] ( 2 ), [Co{PhC(S)‐N(H)‐P(O)(OiPr)2}2{PhC(S)‐N‐P(O)(OiPr)2}2] ( 1a ) and [Co{PhC(S)‐N‐P(O)(OiPr)2}2}(2,2′‐bipy)] ( 3 ), [Co{PhC(S)‐N‐P(O)(OiPr)2}2(1,10‐phen)] ( 4 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)2}2(2,2′‐bipy)] ( 5 ), [Co{PhN(H)‐C(S)‐N‐P(O)(OiPr)2}2(1,10‐phen)] ( 6 ) were investigated. Paramagnetic shifts in the 1H NMR spectrum were observed for high‐spin CoII complexes with HLI,II , incorporating the S‐C‐N‐P‐O chelate moiety and two aromatic chelate ligands. Investigation of the thermal dependence of the magnetic susceptibility has shown that the extended materials 1‐2 and 6 show ferromagnetic exchange between distorted tetrahedral ( 1 , 2 ) or octahedral ( 1a , 6 ) metal atoms whereas 3 and 5 show antiferromagnetic properties. Compound 4 behaves as a spin‐canted ferromagnet, an antiferromagnetic ordering taking place below a critical temperature, Tc = 115 K. Complexes 1 and 1a were investigated by single crystal X‐ray diffraction. The cobalt(II) atom in complex 1 resides a distorted tetrahedral O2S2 environment formed by the C=S sulfur atoms and the P=O oxygen atoms of two deprotonated ligands. Complex 1a has a tetragonal‐bipyramidal structure, Co(Oax)2(Oeq)2(Seq)2, and two neutral ligand molecules are coordinated in the axial positions through the oxygen atoms of the P=O groups. The base of the bipyramid is formed by two anionic ligands in the typical 1,5‐O,S coordination mode. The ligands are in a trans configuration. 相似文献
The reactions of phosphonium‐substituted metallabenzenes and metallapyridinium with bis(diphenylphosphino)methane (DPPM) were investigated. Treatment of [Os{CHC(PPh3)CHC(PPh3)CH}Cl2(PPh3)2]Cl with DPPM produced osmabenzenes [Os{CHC(PPh3)CHC(PPh3)CH}Cl2{(PPh2)CH2(PPh2)}]Cl ( 2 ), [Os{CHC(PPh3)CHC(PPh3)CH}Cl{(PPh2)CH2(PPh2)}2]Cl2 ( 3 ), and cyclic osmium η2‐allene complex [Os{CH?C(PPh3)CH?(η2‐C?CH)}Cl2{(PPh2)CH2(PPh2)}2]Cl ( 4 ). When the analogue complex of osmabenzene 1 , ruthenabenzene [Ru{CHC(PPh3)CHC(PPh3)CH}Cl2(PPh3)2]Cl, was used, the reaction produced ruthenacyclohexadiene [Ru{CH?C(PPh3)CH?C(PPh3)CH}Cl{(PPh2)CH2(PPh2)}2]Cl2 ( 6 ), which could be viewed as a Jackson–Meisenheimer complex. Complex 6 is unstable in solution and can easily be convert to the cyclic ruthenium η2‐allene complexes [Ru{CH?C(PPh3)CH?(η2‐C?CH)}Cl{(PPh2)CH2(PPh2)}2]Cl2 ( 7 ) and [Ru{CH?C(PPh3)CH?(η2‐C?CH)}Cl2{(PPh2)CH2(PPh2)}2]Cl ( 8 ). The key intermediates of the reactions have been isolated and fully characterized, further supporting the proposed mechanism for the reactions. Similar reactions also occurred in phosphonium‐substituted metallapyridinium [OsCl2{NHC(CH3)C(Ph)C(PPh3)CH}(PPh3)2]BF4 to give the cyclic osmium η2‐allene‐imine complex [OsCl2{NH?C(CH3)C(Ph)?(η2‐C?CH)}{(PPh2)CH2(PPh2)}(PPh3)]BF4 ( 11 ). 相似文献
Factors affecting the product distributions in ethylene/styrene copolymerizations catalyzed by Cp*TiCl2(O‐2,6‐iPr2C6H3) are explored in the presence of various cocatalysts at high styrene/ethylene feed ratios (at 40 and 55 °C). Ethylene/styrene copolymers were the sole product when the reactions were conducted in the presence of [PhN(H)Me2][B(C6F5)4] and AliBu3/Al(octyl)3 even at 55 and 70 °C, whereas syndiotactic polystyrene was by‐produced when the polymerizations were performed at >40 °C in the presence of MAO; the ratios of the copolymer/SPS were affected by the reaction temperature as well as Al cocatalyst employed.
The polymerization of 2‐butene and its copolymerization with ethylene have been investigated using four kinds of dichlorobis(β‐diketonato)titanium complexes, [ArN(CH2)3NAr]TiCl2 (Ar = 2,6‐iPr2C6H3) and typical metallocene catalysts. The obtained copolymers display lower melting points than those produced of homopolyethylene under the same polymerization conditions. 13C NMR analysis indicates that 9.3 mol‐% of 2‐butene units were incorporated into the polymer chains with Ti(BFA)2Cl2‐MAO as the catalyst system. With the trans‐2‐butene a higher copolymerization rate was observed than with cis‐2‐butene. A highly regioselective catalyst system for propene polymerization, [ArN(CH2)3NAr]TiCl2 complex using a mixture of triisobutylaluminium and Ph3CB(C6F5)4 as cocatalyst, was found to copolymerize a mixture of 1‐butene and trans‐2‐butene with ethylene up to 3.1 mol‐%. Monomer isomerization‐polymerization proceeds with typical metallocene catalysts to produce copolymers consisting of ethylene and 1‐butene. 相似文献
Five new limonoids, including andhraxylocarpins A and B ( 1 and 2 ) which contain a 9‐oxa‐tricyclo[3.3.2.17, 10]undecane‐2‐ene motif, andhraxylocarpins C and D ( 3 and 4 ), which contain a (Z)‐bicyclo[5.2.1]dec‐3‐en‐8‐one substructure, and andhraxylocarpin E ( 5 ), which contains a tricyclo[3.3.1.13, 6]decane‐9‐one scaffold, were isolated from the seeds of two true mangroves, Xylocarpus granatum and Xylocarpus moluccensis, that were collected in the estuaries of Andhra Pradesh, India. The absolute configurations of these compounds were determined by extensive NMR investigations, single‐crystal X‐ray diffraction analysis, and by circular dichroism and optical rotatory dispersion spectroscopy, in combination with quantum‐chemical calculations. The pronounced structural diversity of limonoids from these mangroves might originate from environmental factors. 相似文献
The tricyclic azoalkanes, (1α,4α,4aα,7aα)‐4,4a,5,6,7,7a‐hexahydro‐1,4,8,8‐tetramethyl‐1,4‐methano‐1H‐cyclopenta[d]pyridazine ( 1c ), (1α,4α,4aα,6aα)‐4,4a,5,6,6a‐pentahydro‐1,4,7,7‐tetramethyl‐1,4‐methano‐1H‐cyclobuta[d]pyridazine ( 1d ), (1α,4α,4aα,6aα)‐4,4a,6a‐trihydro‐1,4,7,7‐tetramethyl‐1,4‐methano‐1H‐cyclobuta[d]pyridazine ( 1e ), and (1α,4α,4aα,5aα)‐4,4a,5,5a‐tetrahydro‐1,4,6,6‐tetramethyl‐1,4‐methano‐1H‐cyclopropa[d]pyridazine ( 1f ), as well as the corresponding housanes, the 2,3,3,4‐tetramethyl‐substituted tricyclo[3.3.0.02,4]octane ( 2c ), tricyclo[3.2.0.02,4]heptane ( 2d ), and tricyclo[3.2.0.02,4]hept‐6‐ene ( 2e ), were subjected to γ‐irradiation in Freon matrices. The reaction products were identified with the use of ESR and, in part, ENDOR spectroscopy. As expected, the strain on the C‐framework increases on going from the cyclopentane‐annelated azoalkanes and housanes ( 1c and 2c ) to those annelated by cyclobutane ( 1d and 2d ), by cyclobutene ( 1e and 2e ), and by cyclopropane ( 1f ). Accordingly, the products obtained from 1c and 2c in all three Freons used, CFCl3, CF3CCl3, and CF2ClCFCl2, were the radical cations 3c .+ and 2c .+ of 2,3,4,4‐tetramethylbicyclo[3.3.0]oct‐2‐ene and 2,3,3,4‐tetramethylbicyclo[3.3.0]octane‐2,4‐diyl, respectively. In CFCl3 and CF3CCl3 matrices, 1d and 2d yielded analogous products, namely the radical cations 3d .+ and 2d .+ of 2,3,4,4‐tetramethylbicyclo[3.2.0]hept‐2‐ene and 2,3,3,4‐tetramethylbicyclo[3.2.0]heptane‐2,4‐diyl. The radical cations 3c .+ and 3d .+ and 2c .+ and 2d .+ correspond to their non‐annelated counterparts 3a .+ and 3b .+, and 2a .+ and 2b .+ generated previously under the same conditions from 2,3‐diazabicyclo[2.2.1]hept‐2‐ene ( 1a ) and bicyclo[2.1.0]pentane ( 2a ), as well as from their 1,4‐dimethyl derivatives ( 1b and 2b ). However, in a CF2ClCFCl2 matrix, both 1d and 2d gave the radical cation 4d .+ of 2,3,3,4‐tetramethylcyclohepta‐1,4‐diene. Starting from 1e and 2e , the radical cations 4e .+ and 4e′ .+ of the isomeric 1,2,7,7‐ and 1,6,7,7‐tetramethylcyclohepta‐1,3,5‐trienes appeared as the corresponding products, while 1f was converted into the radical cation 4f .+ of 1,5,6,6‐tetramethylcyclohexa‐1,4‐diene which readily lost a proton to yield the corresponding cyclohexadienyl radical 4f .. Reaction mechanisms leading to the pertinent radical cations are discussed. 相似文献
Treatment of the osmabenzene [Os{CHC(PPh3)CHC(PPh3)CH} Cl2(PPh3)2]Cl ( 1 ) with excess 8‐hydroxyquinoline produces monosubstituted osmabenzene [Os{CH C(PPh3) CHC(PPh3)CH}(C9H6NO)Cl(PPh3)]Cl ( 2 ) or disubstituted osmabenzene [Os{CHC(PPh3)CHC(PPh3)CH} (C9H6NO)2]Cl ( 3 ) under different reaction conditions. Osmabenzene 2 evolves into cyclic η2‐allene‐coordinated complex [Os{CH?C(PPh3)CH=(η2‐C?CH2)}(C9H6NO)(PPh3)2]Cl ( 4 ) in the presence of excess PPh3 and NaOH, presumably involving a P? C bond cleavage of the metallacycle. Reaction of 4 with excess 8‐hydroxyquinoline under air affords the SNAr product [(C9H6NO)Os{CHC(PPh3)CHCHC} (C9H6NO)(PPh3)]Cl ( 5 ). Complex 4 is fairly reactive to a nucleophile in the presence of acid, which could react with water to give carbonyl complex [Os{CH?C(PPh3)CH?CH2}(C9H6NO) (CO)(PPh3)2]Cl ( 6 ). Complex 4 also reacts with PPh3 in the presence of acid and results in a transformation to [Os {CHC(PPh3)CHCHC}(C9H6NO)Cl (PPh3)2]Cl ( 7 ) and [Os{CH?C(PPh3) CH=(η2‐C?CH(PPh3))}(C9H6NO) Cl(PPh3)]Cl ( 8 ). Further investigation shows that the ratio of 7 and 8 is highly dependent on the amount of the acid in the reaction. 相似文献
X‐ray crystal structure analysis of the lithiated allylic α‐sulfonyl carbanions [CH2?CHC(Me)SO2Ph]Li ? diglyme, [cC6H8SO2tBu]Li ? PMDETA and [cC7H10SO2tBu]Li ? PMDETA showed dimeric and monomeric CIPs, having nearly planar anionic C atoms, only O?Li bonds, almost planar allylic units with strong C?C bond length alternation and the s‐trans conformation around C1?C2. They adopt a C1?S conformation, which is similar to the one generally found for alkyl and aryl substituted α‐sulfonyl carbanions. Cryoscopy of [EtCH?CHC(Et)SO2tBu]Li in THF at 164 K revealed an equilibrium between monomers and dimers in a ratio of 83:17, which is similar to the one found by low temperature NMR spectroscopy. According to NMR spectroscopy the lone‐pair orbital at C1 strongly interacts with the C?C double bond. Low temperature 6Li,1H NOE experiments of [EtCH?CHC(Et)SO2tBu]Li in THF point to an equilibrium between monomeric CIPs having only O?Li bonds and CIPs having both O?Li and C1?Li bonds. Ab initio calculation of [MeCH?CHC(Me)SO2Me]Li ? (Me2O)2 gave three isomeric CIPs having the s‐trans conformation and three isomeric CIPs having the s‐cis conformation around the C1?C2 bond. All s‐trans isomers are more stable than the s‐cis isomers. At all levels of theory the s‐trans isomer having O?Li and C1?Li bonds is the most stable one followed by the isomer which has two O?Li bonds. The allylic unit of the C,O,Li isomer shows strong bond length alternation and the C1 atom is in contrast to the O,Li isomer significantly pyramidalized. According to NBO analysis of the s‐trans and s‐cis isomers, the interaction of the lone pair at C1 with the π* orbital of the CC double bond is energetically much more favorable than that with the “empty” orbitals at the Li atom. The C1?S and C1?C2 conformations are determined by the stereoelectronic effects nC–σSR* interaction and allylic conjugation. 1H DNMR spectroscopy of racemic [EtCH?CHC(Et)SO2tBu]Li, [iPrCH?CHC(iPr)SO2tBu]Li and [EtCH?C(Me)C(Et)SO2tBu]Li in [D8]THF gave estimated barriers of enantiomerization of ΔG≠=13.2 kcal mol?1 (270 K), 14.2 kcal mol?1 (291 K) and 14.2 kcal mol?1 (295 K), respectively. Deprotonation of sulfone (R)‐EtCH?CHCH(Et)SO2tBu (94 % ee) with nBuLi in THF at ?105 °C occurred with a calculated enantioselectivity of 93 % ee and gave carbanion (M)‐[EtCH?CHC(Et)SO2tBu]Li, the deuteration and alkylation of which with CF3CO2D and MeOCH2I, respectively, proceeded with high enantioselectivities. Time‐dependent deuteration of the enantioenriched carbanion (M)‐[EtCH?CHC(Et)SO2tBu]Li in THF gave a racemization barrier of ΔG≠=12.5 kcal mol?1 (168 K), which translates to a calculated half‐time of racemization of t1/2=12 min at ?105 °C. 相似文献
New Ti and Zr complexes that bear imine–phenoxy chelate ligands, [{2,4‐di‐tBu‐6‐(RCH=N)‐C6H4O}2MCl2] ( 1 : M=Ti, R=Ph; 2 : M=Ti, R=C6F5; 3 : M=Zr, R=Ph; 4 : M=Zr, R=C6F5), were synthesized and investigated as precatalysts for ethylene polymerization. 1H NMR spectroscopy suggests that these complexes exist as mixtures of structural isomers. X‐ray crystallographic analysis of the adduct 1 ?HCl reveals that it exists as a zwitterionic complex in which H and Cl are situated in close proximity to one of the imine nitrogen atoms and the central metal, respectively. The X‐ray molecular structure also indicates that one imine phenoxy group with the syn C?N configuration functions as a bidentate ligand, whereas the other, of the anti C?N form, acts as a monodentate phenoxy ligand. Although Zr complexes 3 and 4 with methylaluminoxane (MAO) or [Ph3C]+[B(C6F5)4]?/AliBu3 displayed moderate activity, the Ti congeners 1 and 2 , in association with an appropriate activator, catalyzed ethylene polymerization with high efficiency. Upon activation with MAO at 25 °C, 2 displayed a very high activity of 19900 (kg PE) (mol Ti)?1 h?1, which is comparable to that for [Cp2TiCl2] and [Cp2ZrCl2], although increasing the polymerization temperature did result in a marked decrease in activity. Complex 2 contains a C6F5 group on the imine nitrogen atom and mediated nonliving‐type polymerization, unlike the corresponding salicylaldimine‐type complex. Conversely, with [Ph3C]+[B(C6F5)4]?/AliBu3 activation, 1 exhibited enhanced activity as the temperature was increased (25–75 °C) and maintained very high activity for 60 min at 75 °C (18740 (kg PE) (mol Ti)?1 h?1). 1H NMR spectroscopic studies of the reaction suggest that this thermally robust catalyst system generates an amine–phenoxy complex as the catalytically active species. The combinations 1 /[Ph3C]+[B(C6F5)4]?/AliBu3 and 2 /MAO also worked as high‐activity catalysts for the copolymerization of ethylene and propylene. 相似文献