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1.
The bis(hydride) dimolybdenum complex, [Mo2(H)2{HC(N‐2,6‐iPr2C6H3)2}2(thf)2], 2 , which possesses a quadruply bonded Mo2II core, undergoes light‐induced (365 nm) reductive elimination of H2 and arene coordination in benzene and toluene solutions, with formation of the MoI2 complexes [Mo2{HC(N‐2,6‐iPr2C6H3)2}2(arene)], 3?C6H6 and 3?C6H5Me , respectively. The analogous C6H5OMe, p‐C6H4Me2, C6H5F, and p‐C6H4F2 derivatives have also been prepared by thermal or photochemical methods, which nevertheless employ different Mo2 complex precursors. X‐ray crystallography and solution NMR studies demonstrate that the molecule of the arene bridges the molybdenum atoms of the MoI2 core, coordinating to each in an η2 fashion. In solution, the arene rotates fast on the NMR timescale around the Mo2‐arene axis. For the substituted aromatic hydrocarbons, the NMR data are consistent with the existence of a major rotamer in which the metal atoms are coordinated to the more electron‐rich C?C bonds.  相似文献   

2.
The bis(imino)pyridine 2,6‐(2,6‐iPr2‐C6H3N?CPh)2‐C5H3N (iPrBPDI) molybdenum dinitrogen complex, [{(iPrBPDI)Mo(N2)}2211‐N2)] has been prepared and contains both weakly (terminal) and modestly (bridging) activated N2 ligands. Addition of ammonia resulted in sequential N? H bond activations, thus forming bridging parent imido (μ‐NH) ligands with concomitant reduction of one of the imines of the supporting chelate. Using primary and secondary amines, model intermediates have been isolated that highlight the role of metal–ligand cooperativity in NH3 oxidation.  相似文献   

3.
The preparation of an unprecedented GeI‐GeI bonded digermylene [K2{Ge2(μ‐κ224‐2,6‐(2,6‐iPr2C6H3‐N)2‐4‐CH3C5H2N)2}] in an eclipsed conformation stabilized by two bridging diamidopyridyl ligands is presented. Although it exhibits an eclipsed conformation, the Ge−Ge bond length is 2.5168(6) Å, which is shorter than those in the trans ‐bent and gauche digermylenes. In combination with two pendant amido groups, the GeI2 motif is employed as a building block to assemble the first example of octagermylene [Ge4(μ‐κ21‐2,6‐(2,6‐iPr2C6H3‐N)2‐4‐CH3C5H2N)2]2 showing a cyclic configuration and containing three distinct types of GeI−GeI bonds.  相似文献   

4.
Olefin polymerizations catalyzed by Cp′TiCl2(O‐2,6‐iPr2C6H3) ( 1 – 5 ; Cp′ = cyclopentadienyl group), RuCl2(ethylene)(pybox) { 7 ; pybox = 2,6‐bis[(4S)‐4‐isopropyl‐2‐oxazolin‐2‐yl]pyridine}, and FeCl2(pybox) ( 8 ) were investigated in the presence of a cocatalyst. The Cp*TiCl2(O‐2,6‐iPr2C6H3) ( 5 )–methylaluminoxane (MAO) catalyst exhibited remarkable catalytic activity for both ethylene and 1‐hexene polymerizations, and the effect of the substituents on the cyclopentadienyl group was an important factor for the catalytic activity. A high level of 1‐hexene incorporation and a lower rE · rH value with 5 than with [Me2Si(C5Me4)(NtBu)]TiCl2 ( 6 ) were obtained, despite the rather wide bond angle of Cp Ti O (120.5°) of 5 compared with the bond angle of Cp Ti N of 6 (107.6°). The 7 –MAO catalyst exhibited moderate catalytic activity for ethylene homopolymerization and ethylene/1‐hexene copolymerization, and the resultant copolymer incorporated 1‐hexene. The 8 –MAO catalyst also exhibited activity for ethylene polymerization, and an attempted ethylene/1‐hexene copolymerization gave linear polyethylene. The efficient polymerization of a norbornene macromonomer bearing a ring‐opened poly(norbornene) substituent was accomplished by ringopening metathesis polymerization with the well‐defined Mo(CHCMe2Ph)(N‐2,6‐iPr2C6H3)[OCMe(CF3)2]2 ( 10 ). The key step for the macromonomer synthesis was the exclusive end‐capping of the ring‐opened poly(norbornene) with p‐Me3SiOC6H4CHO, and the use of 10 was effective for this polymerization proceeding with complete conversion. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4613–4626, 2000  相似文献   

5.
Treating [Cp*V(μ‐Cl)2]3 (Cp* = C5Me5) and [(2,6‐i‐Pr2C6H3N)2MoMe2], respectively, with Me3SnF afforded the title compounds [Cp*V(μ‐F)2]4 ( 1 ) and [(2,6‐i‐Pr2C6H3N)2MoF2] · THF ( 2 ). 1 has a tetrameric structure, in which four V atoms can be regarded as being arranged at the vertices of a distorted tetrahedron, with four long edges bridged by one F atom and each of the other two short edges bridged by two F atoms with a mean V–F bond length of 2.00 Å. A hydrolyzed product of 2 , [(2,6‐i‐Pr2C6H3N)6Mo43‐F)2Me2(μ‐O)4] ( 3 ) was characterized by elemental analyses and X‐ray single crystal study. The X‐ray diffraction analysis reveals that 3 has a unique tetranuclear structure, containing two five and two six coordinated Mo atoms connecting each other by four μ‐O and two μ3‐F atoms. The geometries around the two Mo atoms can be described having distorted trigonal bipyramidal and distorted octahedral coordination spheres, respectively. The Mo–(μ‐O) bond lengths are 1.813 Å (average) for five coordinated Mo atoms and 2.030 Å (average) for those of six coordinated, respectively, indicating an additional π bonding between five coordinated Mo atoms and the μ‐O atoms. The Mo–(μ3‐F) distances range from 2.291 to 2.352 Å.  相似文献   

6.
A series of new titanium(IV) complexes with o‐metalated arylimine and/or cis‐9,10‐dihydrophenanthrenediamide ligands, [o‐C6H4(CH?NR)TiCl3] (R=2,6‐iPr2C6H3 ( 3 a ), 2,6‐Me2C6H3 ( 3 b ), tBu ( 3 c )), [cis‐9,10‐PhenH2(NR)2TiCl2] (PhenH2=9,10‐dihydrophenanthrene; R=2,6‐iPr2C6H3 ( 4 a ), 2,6‐Me2C6H3 ( 4 b ), tBu ( 4 c )), [{cis‐9,10‐PhenH2(NR)2}{o‐C6H4(HC?NR)}TiCl] (R=2,6‐iPr2C6H3 ( 5 a ), 2,6‐Me2C6H3 ( 5 b ), tBu ( 5 c )), have been synthesised from the reactions of TiCl4 with o‐C6H4(CH?NR)Li (R=2,6‐iPr2C6H3, 2,6‐Me2C6H3, tBu). Complexes 4 and 5 were formed unexpectedly from the reactions of TiCl4 with two or three equivalents of the corresponding o‐C6H4(CH?NR)Li followed by sequential intramolecular C? C bond‐forming reductive elimination and oxidative coupling reactions. Attempts to isolate the intermediates, [{o‐C6H4(CH?NR)}2TiCl2] ( 2 ), were unsuccessful. All complexes were characterised by 1H and 13C NMR spectroscopy, and the molecular structures of 3 a , 4 a – c , 5 a , and 5 c were determined by X‐ray crystallography.  相似文献   

7.
5‐Coordinated methoxybenzylidene complexes M(=NAr)(=CH?C6H4?o‐OMe)(OtBuF3)2 (Ar=2,6‐iPr2C6H3; tBuF3=CMe2(CF3)) of Mo ( 1mMo ) and W ( 1mW ) were synthesized by cross‐metathesis from the corresponding neophylidene/neopentylidene precursors and o‐methoxystyrene. 1mMo and 1mW were grafted onto the surface of silica partially dehydroxylated at 700 °C to give well‐defined silica‐supported alkylidenes (≡SiO)M(=NAr)(=CH?C6H4?o‐OMe)(OtBuF3) (M=Mo ( 1Mo ), W ( 1W )). Supported methoxybenzylidene complexes were tested in metathesis of cis‐4‐nonene, 1‐nonene, and ethyl oleate, and compared to their molecular precursors and supported classical analogs (≡SiO)M(=NAr)(=CHCMe2R)(OtBuF3) (M=Mo, R=Ph ( 2Mo ), M=W, R=Me ( 2W )). Both grafted complexes 1Mo and 1W show significantly better performance as compared to their molecular precursors 1mMo and 1mW but are less efficient than the classical 4‐coordinated alkylidenes 2Mo and 2W . Noteworthy, both 1Mo and 1W can reach equilibrium conversion in metathesis of cis‐4‐nonene at catalyst loadings as low as 50 ppm.  相似文献   

8.
The first examples of magnesium(I) dimers bearing tripodal ligands, [(Mg{κ3N,N′,O‐(ArNCMe)2(OCCPh2)CH})2] [Ar=2,6‐iPr2C6H3 (Dip) 7 , 2,6‐Et2C6H3 (Dep) 8 , or mesityl (Mes) 9 ] have been prepared by post‐synthetic modification of the β‐diketiminato ligands of previously reported magnesium(I) systems, using diphenylketene, O?C?CPh2. In contrast, related reactions between β‐diketiminato magnesium(I) dimers and the isoelectronic ketenimine, MesN?C?CPh2, resulted in reductive insertion of the substrate into the Mg?Mg bond of the magnesium(I) reactant, and formation of [{(Nacnac)Mg}2{μ‐κ2N,C‐(Mes)NCCPh2}] (Nacnac=[(ArNCMe)2CH]?; Ar=Dep 10 or Mes 11 ). Reactions of the four‐coordinate magnesium(I) dimer 8 with excess CO2 are readily controlled, and cleanly give carbonate [(LMg)2(μ‐κ22‐CO3)] 12 (L=[κ3N,N′,O‐(DepNCMe)2(OCCPh2)CH]?; thermodynamic product), or oxalate [(LMg)2(μ‐κ22‐C2O4)] 13 (kinetic product), depending on the reaction temperature. Compound 12 and CO are formed by reductive disproportionation of CO2, whereas 13 results from reductive coupling of two molecules of the gas. Treatment of 8 with an excess of N2O cleanly gives the μ‐oxo complex [(LMg)2(μ‐O)] 14 , which reacts facilely with CO2 to give 12 . This result presents the possibility that 14 is an intermediate in the formation of 12 from the reaction of 8 and CO2. In contrast to its reactions with CO2, 8 reacts with SO2 over a wide temperature range to give only one product; the first example of a magnesium dithionite complex, [(LMg)2(μ‐κ22‐S2O4)] 16 , which is formed by reductive coupling of two molecules of SO2, and is closely related to f‐block metal dithionite complexes derived from similar SO2 reductive coupling processes. On the whole, this study strengthens previously proposed analogies between the reactivities of magnesium(I) systems and low‐valent f‐block metal complexes, especially with respect to small molecule activations.  相似文献   

9.
The reaction of one equivalent of LAlH2 ( 1 ; L=HC(CMeNAr)2, Ar=2,6‐iPr2C6H3, β‐diketiminate ligand) with two equivalents of 2‐mercapto‐4,6‐dimethylpyrimidine hydrate resulted in LAl[(μ‐S)(m‐C4N2H)(CH2)2]2 ( 2 ) in good yield. Similarly, when N‐2‐pyridylsalicylideneamine, N‐(2,6‐diisopropylphenyl)salicylaldimine, and ethyl 3‐amino‐4,5,6,7‐tetrahydrobenzo[b]thiophene‐2‐carboxylate were used as starting materials, the corresponding products LAl[(μ‐O)(o‐C6H4)CN(C5NH4)]2 ( 3 ), LAlH[(μ‐O)(o‐C4H4)CN(2,6‐iPr2C6H3)] ( 4 ), and LAl[(μ‐NH)(o‐C8SH8)(COOC2H5)]2 ( 5 ) were isolated. Compounds 2 – 5 were characterized by 1H and 13C NMR spectroscopy as well as by single‐crystal X‐ray structural analysis. Surprisingly, compounds 2 – 5 exhibit good catalytic activity in addition reactions of aldehydes with trimethylsilyl cyanide (TMSCN).  相似文献   

10.
Treatment of the chlorides (L2,6‐iPr2Ph)2LnCl (L2,6‐iPr2Ph = [(2,6‐iPr2C6H3)NC(Me)CHC(Me)N(C6H5)]?) with 1 equiv. of NaNH(2,6‐iPr2C6H3) afforded the monoamides (L2,6‐iPr2Ph)2LnNH(2,6‐iPr2C6H3) (Ln = Y ( 1 ), Yb ( 2 )) in good yields. Anhydrous LnCl3 reacted with 2 equiv. of NaL2,6‐iPr2Ph in THF, followed by treatment with 1 equiv. of NaNH(2,6‐iPr2C6H3), giving the analogues (L2,6‐iPr2Ph)2LnNH(2,6‐iPr2C6H3) (Ln = Sm ( 3 ), Nd ( 4 )). Two monoamido complexes stabilized by two L2‐Me ligands, (L2‐Me)2LnNH(2,6‐iPr2C6H3) (L2‐Me = [N(2‐MeC6H4)C(Me)]2CH)?; Ln = Y ( 5 ), Yb ( 6 )), were also synthesized by the latter route. Complexes 1 , 2 , 3 , 4 , 5 , 6 were fully characterized, including X‐ray crystal structure analyses. Complexes 1 , 2 , 3 , 4 , 5 , 6 are isostructural. The central metal in each complex is ligated by two β‐diketiminato ligands and one amido group in a distorted trigonal bipyramid. All the complexes were found to be highly active in the ring‐opening polymerization of L‐lactide (L‐LA) and ε‐caprolactone (ε‐CL) to give polymers with relatively narrow molar mass distributions. The activity depends on both the central metal and the ligand (Yb < Y < Sm ≈ Nd and L2‐Me < L2,6‐iPr2Ph). Remarkably, the binary 3/benzyl alcohol (BnOH) system exhibited a striking ‘immortal’ nature and proved able to quantitatively convert 5000 equiv. of L‐LA with up to 100 equiv. of BnOH per metal initiator. All the resulting PLAs showed monomodal, narrow distributions (Mw/Mn = 1.06 ? 1.08), with molar mass (Mn) decreasing proportionally with an increasing amount of BnOH. The binary 4/BnOH system also exhibited an ‘immortal’ nature in the polymerization of ε‐CL in toluene. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

11.
To clarify the nature of the Mo?Carene interaction in terphenyl complexes with quadruple Mo?Mo bonds, ether adducts of composition [Mo2(Ar′)(I)(O2CR)2(OEt2)] have been prepared and characterized (Ar′=ArXyl2, R=Me; Ar′=ArMes2, R=Me; Ar′=ArXyl2, R=CF3) (Mes=mesityl; Xyl=2,6‐Me2C6H3, from now on xylyl) and their reactivity toward different neutral Lewis bases investigated. PMe3, P(OMe)3 and PiPr3 were chosen as P‐donors and the reactivity studies complemented with the use of the C‐donors CNXyl and CN2C2Me4 (1,3,4,5‐tetramethylimidazol‐2‐ylidene). New compounds of general formula [Mo2(Ar′)(I)(O2CR)2( L )] were obtained, except for the imidazol‐2‐ylidene ligand that yielded a salt‐like compound of composition [Mo2(ArXyl2)(O2CMe)2(CN2C2Me4)2]I. The Mo?Carene interaction in these complexes has been analyzed with the aid of X‐ray data and computational studies. This interaction compensates the coordinative and electronic unsaturation of one of the Mo atoms in the above complexes, but it seems to be weak in terms of sharing of electron density between the Mo and Carene atoms and appears to have no appreciable effect in the length of the Mo?Mo, Mo?X, and Mo? L bonds present in these molecules.  相似文献   

12.
The syntheses and reactivity of the two N‐heterocyclic carbene (NHC)→ silylene complexes 2 and 4 have been investigated. The latter are easily accessible by reaction of the zwitterionic, N‐heterocyclic silylene LSi: 1 [L=Ar‐N‐C(=CH2)CH?C(Me)‐N‐Ar, Ar=2,6‐iPr2C6H3] with 1,3,4,5‐tetramethylimidazol‐2‐ylidene and 1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene, respectively. While compound 2 undergoes facile rearrangement above ?20 °C to give the unsymmetrical N‐heterocyclic silylcarbene 3 , the derivative 4 remains unchanged even after boiling in benzene. The remarkable reactivity of 3 and 4 towards cyclohexylisocyanide has been examined which leads in a unique series of C? H, Si? H, and C? N bond activations to the new triaminosilanes 5 and 6 , respectively. The novel compounds 3 , 4 , 5 , and 6 were fully characterized by 1H, 13C, and 29Si NMR spectroscopy, EI‐MS, elemental analysis, and single‐crystal X‐ray diffraction.  相似文献   

13.
We report herein three new modes of reactivity between arylazides N3Ar with a bulky copper(I) β-diketiminate. Addition of N3ArX3 (ArX3=2,4,6-X3C6H2; X=Cl or Me) to [iPr2NN]Cu(NCMe) results in triazenido complexes from azide attack on the β-diketiminato backbone. Reaction of [iPr2NN]Cu(NCMe) with bulkier azides N3Ar leads to terminal nitrenes [iPr2NN]Cu]=NAr that dimerize via formation of a C−C bond at the arylnitrene p-position to give the dicopper(II) diketimide 4 (Ar=2,6-iPr2C6H3) or undergo nitrile insertion to give diazametallocyclobutene 8 (Ar=4-Ph-2,6-iPr2C6H2). Importantly, reactivity studies reveal both 4 and 8 to be “masked” forms of the terminal nitrenes [iPr2NN]Cu=NAr that undergo nitrene group transfer to PMe3, tBuNC, and even into a benzylic sp3 C−H bond of ethylbenzene.  相似文献   

14.
This contribution reports on a new family of NiII pincer complexes featuring phosphinite and functional imidazolyl arms. The proligands RPIMCHOPR′ react at room temperature with NiII precursors to give the corresponding complexes [(RPIMCOPR′)NiBr], where RPIMCOPRPCP‐{2‐(R′2PO),6‐(R2PC3H2N2)C6H3}, R=iPr, R′=iPr ( 3 b , 84 %) or Ph ( 3 c , 45 %). Selective N‐methylation of the imidazole imine moiety in 3 b by MeOTf (OTf=OSO2CF3) gave the corresponding imidazoliophosphine [(iPrPIMIOCOPiPr)NiBr][OTf], 4 b , in 89 % yield (iPrPIMIOCOPiPrPCP‐{2‐(iPr2PO),6‐(iPr2PC4H5N2)C6H3}). Treating 4 b with NaOEt led to the NHC derivative [(NHCCOPiPr)NiBr], 5 b , in 47 % yield (NHCCOPiPrPCC‐{2‐(iPr2PO),6‐(C4H5N2)C6H3)}). The bromo derivatives 3–5 were then treated with AgOTf in acetonitrile to give the corresponding cationic species [(RPIMCOPR)Ni(MeCN)][OTf] [R=Ph, 6 a (89 %) or iPr, 6 b (90 %)], [(RPIMIOCOPR)Ni(MeCN)][OTf]2 [R=Ph, 7 a (79 %) or iPr, 7 b (88 %)], and [(NHCCOPR)Ni(MeCN)][OTf] [R=Ph, 8 a (85 %) or iPr, 8 b (84 %)]. All new complexes have been characterized by NMR and IR spectroscopy, whereas 3 b , 3 c , 5 b , 6 b , and 8 a were also subjected to X‐ray diffraction studies. The acetonitrile adducts 6 – 8 were further studied by using various theoretical analysis tools. In the presence of excess nitrile and amine, the cationic acetonitrile adducts 6 – 8 catalyze hydroamination of nitriles to give unsymmetrical amidines with catalytic turnover numbers of up to 95.  相似文献   

15.
Herein we report the employment of the quintuply bonded dichromium amidinates [Cr{κ2‐HC(N‐2,6‐iPr2C6H3)(N‐2,6‐R2C6H3)}]2 (R=iPr ( 1 ), Me ( 7 )) as catalysts to mediate the [2+2+2] cyclotrimerization of terminal alkynes giving 1,3,5‐trisubstituted benzenes. During the catalysis, the ultrashort Cr−Cr quintuple bond underwent reversible cleavage/formation, corroborated by the characterization of two inverted arene sandwich dichromium complexes (μ‐η66‐1,3,5‐(Me3Si)3C6H3)[Cr{κ2‐HC(N ‐2,6‐iPr2C6H3)(N ‐2,6‐R2C6H3)}]2 (R=iPr ( 5 ), Me ( 8 )). In the presence of σ donors, such as THF and 2,4,6‐Me3C6H2CN, the bridging arene 1,3,5‐(Me3Si)3C6H3 in 5 and 8 was extruded and 1 and 7 were regenerated. Theoretical calculations were employed to disclose the reaction pathways of these highly regioselective [2+2+2] cylcotrimerization reactions of terminal alkynes.  相似文献   

16.
This paper describes the formation of new platinacyclic complexes derived from the phosphine ligands PiPr2Xyl, PMeXyl2, and PMe2Ar (Xyl=2,6‐Me2C6H3 and Ar=2,6‐(2,6‐Me2C6H3)2‐C6H3) as well as reactivity studies of the trans‐[Pt(C^P)2] bis‐metallacyclic complex 1 a derived from PiPr2Xyl. Protonation of compound 1 a with [H(OEt2)2][BArF] (BArF=B[3,5‐(CF3)2C6H3]4) forms a cationic δ‐agostic structure 4 a , whereas α‐hydride abstraction employing [Ph3C][PF6] produces a cationic platinum carbene trans‐[Pt{PiPr2(2,6‐CH(Me)C6H3}{PiPr2(2,6‐CH2(Me)C6H3}][PF6] ( 8 ). Compounds 4 a and 8 react with H2 to yield the same 1:3 equilibrium mixture of 4 a and trans‐[PtH(PiPr2Xyl)2][BArF] ( 6 ), in which one of the phosphine ligands participates in a δ‐agostic interaction. DFT calculations reveal that H2 activation by 8 occurs at the highly electrophilic alkylidene terminus with no participation of the metal. The two compounds 4 a and 8 experience C–C coupling reactions of a different nature. Thus, 4 a gives rise to complex trans‐[PtH{(E)‐1,2‐bis(2‐(PiPr2)‐3‐MeC6H3)CH?CH}] ( 7 ) that contains a tridentate diphosphine–alkene ligand, through agostic C?H oxidative cleavage and C–C reductive coupling steps, whereas the C–C coupling reaction in 8 involves classical migratory insertion of its [Pt?CH] and [Pt?CH2] bonds promoted by platinum coordination of CO or CNXyl. The mechanisms of the C?C bond‐forming reactions have also been investigated by computational methods.  相似文献   

17.
The quadruply bonded Mo24+ complex Mo2(DAniF)3(OOCC6F5) ( 1 ) [DAniF = N,N′‐bis(4‐methoxyphenyl)formamidinate] was synthesized. The solvate Mo2(DAniF)3(OOCC6F5) · (C6H6) ( 2 ) and co‐crystal Mo2(DAniF)3(OOCC6F5) · (C10H8) ( 3 ) complexes were obtained by self‐assembly of crystals of 1 with benzene and naphthalin, respectively. Compounds 1 , 2 , and 3 were structurally characterized by single‐crystal X‐ray diffraction. In monomer 1 , the Mo–Mo bond length of 2.0874(6) Å is typical for dimolybdenum quadruple bonds. The solvate complex 2 was stabilized by weak π–π stacking interactions between the benzene molecule and the pentafluorophenyl ring (as indicated by a center‐to‐center distance of 3.838(10) Å and a center‐to‐plane distance of 3.712(4) Å between phenyl and pentafluorophenyl ring) and intermolecular C–H ··· F–C interactions (the shortest F ··· H distance is 2.560(2) Å). In complex 3 , a one‐dimensional chain was formed by C–H ··· F–C interactions between the hydrogen atoms in naphthalin and the fluorine atoms in the monomer (H ··· F distances of 2.582(2) Å). Information on the structures in solution of the three crystals was obtained by 1H NMR spectroscopy.  相似文献   

18.
Five examples of unsymmetrical 1,2‐bis (arylimino) acenaphthene ( L1 – L5 ), each containing one N‐2,4‐bis (dibenzocycloheptyl)‐6‐methylphenyl group and one sterically and electronically variable N‐aryl group, have been used to prepare the N,N′‐nickel (II) halide complexes, [1‐[2,4‐{(C15H13}2–6‐MeC6H2N]‐2‐(ArN)C2C10H6]NiX2 (X = Br: Ar = 2,6‐Me2C6H3 Ni1 , 2,6‐Et2C6H3 Ni2 , 2,6‐i‐Pr2C6H3 Ni3 , 2,4,6‐Me3C6H2 Ni4 , 2,6‐Et2–4‐MeC6H2 Ni5 ) and (X = Cl: Ar = 2,6‐Me2C6H3 Ni6 , 2,6‐Et2C6H3 Ni7 , 2,6‐i‐Pr2C6H3 Ni8 , 2,4,6‐Me3C6H2 Ni9 , 2,6‐Et2–4‐MeC6H2 Ni10 ), in high yield. The molecular structures Ni3 and Ni7 highlight the extensive steric protection imparted by the ortho‐dibenzocycloheptyl group and the distorted tetrahedral geometry conferred to the nickel center. On activation with either Et2AlCl or MAO, Ni1 – Ni10 exhibited very high activities for ethylene polymerization with the least bulky Ni1 the most active (up to 1.06  ×  107 g PE mol?1(Ni) h?1 with MAO). Notably, these sterically bulky catalysts have a propensity towards generating very high molecular weight polyethylene with moderate levels of branching and narrow dispersities with the most hindered Ni3 and Ni8 affording ultra‐high molecular weight material (up to 1.5  ×  106 g mol?1). Indeed, both the activity and molecular weights of the resulting polyethylene are among the highest to be reported for this class of unsymmetrical 1,2‐bis (imino)acenaphthene‐nickel catalyst.  相似文献   

19.
The reactivity of the As‐zincosilaarsene LZn?As=SiL′ A (L=[CH(CMeNDipp)2]?, Dipp=2,6‐iPr2C6H3, L′=[{C(H)N(2,6‐iPr2‐C6H3)}2]2?) towards small molecules was investigated. Due to the pronounced zwitterionic character of the Si=As bond of A , it undergoes addition reactions with H2O and NH3, forming LZnAs(H)SiOH(L′) 1 and LZnAs(H)SiNH2(L′) 2 . Oxygenation of A with N2O at ?60 °C furnishes the deep blue 1,2‐disiloxydiarsene, [LZnOSi(L′)As]2 4 , presumably via dimerization of the arsinidene intermediate LZnOSi(L′)As 3 . Oxygenation of A with CO2 leads to the monomeric arsaethynolato siloxido zinc complex LZnOSi(L′)(OC≡As) 5 , essentially trapping the intermediary arsinidene 3 with liberated CO following initial oxidation of the Si=As bond. DFT calculations confirm the ambident coordination mode of the anionic [AsCO] ligand in solution, with the O‐arsaethynolato [As≡C?O].? in 5 , and the As‐arsaketenylido ligand mode [O=C=As]? present in LZnO?Si(L′)(?As=C=O) 5′ akin to the analogous phosphorus system, [PCO]?.  相似文献   

20.
Heterobimetallic Phosphanido-bridged Dinuclear Complexes - Syntheses of cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6-iPr3C6H2)}2M(CO)4] (R?Me, M?Cr, Mo; R?H, M?Mo) The zirconocene bisphosphanido complexes [(η-C5H4R)2Zr{PH(2,4,6-iPr3C6H2)}2] (R?Me, H) react with [(NBD)M(CO)4] (NBD?norbornadiene, M?Cr, Mo) to give only one diastereomer of the phosphanido-bridged heterobimetallic dinuclear complexes cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6-iPr3C6H2)}2M(CO)4] [R?Me, M?Cr ( 1 ), Mo ( 2 ); R?H, M?Mo ( 3 )]. However, no reaction was observed between [(η-C5H5)2Zr{PH(2,4,6-tBu3 C6H2)}2] and [Pt(PPh3)4]. 1—3 were characterised spectroscopically. For 1—3 , the presence of the racemic isomer was shown by NMR spectroscopy. No reaction was observed at room temperature for 3 and CS2, (NO)BF4, Me3NO or PH(2,4,6-Me3C6H2)2. With Et2AlH or PhC?CH decomposition of 3 was observed.  相似文献   

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