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
The reaction of (c‐C6H11)7Si7O9(ONa)3, prepared in situ from (c‐C6H11)7Si7O9(OH)3 ( 1 ), and MnCl2(THF)2 in THF solution resulted in formation of the novel heterobimetallic Mn/Na metallasilsesquioxane complex [(c‐C6H11)7Si7O9(O3Mn)Na(Et2O)]2·Et2O ( 2 ) which was isolated in the form of colorless crystals in 64 % yield. Similar treatment of MnCl2(THF)2 with in situ prepared (c‐C6H11)7Si7O9(OLi)3 afforded the unusual tetramanganese silsesquioxane complex [(c‐C6H11)7Si7O9(O3Mn2Br)LiBr(THF)(Et2O)]2 ( 3 ) in high yield (81 %). Both 2 and 3 were structurally characterized by single‐crystal X‐ray diffraction. 相似文献
Copolymerization of ethylene and styrene with the catalytic system Cp*TiMe3‐B(C6F5)3 under suitable conditions affords a new polymer having a polyethylenic backbone with 4‐phenyl‐1‐butyl branches as the main product. This unexpected result has been ascribed to the multi‐site nature of the catalytic system, containing a species able to co‐oligomerize ethylene and styrene to 6‐phenyl‐1‐hexene (which was actually identified in the polymerization mixture), and another species able to copolymerize the latter with ethylene. 相似文献
Monophosphine‐o‐carborane has four competitive coordination modes when it coordinates to metal centers. To explore the structural transitions driven by these competitive coordination modes, a series of monophosphine‐o‐carborane Ir,Rh complexes were synthesized and characterized. [Cp*M(Cl)2{1‐(PPh2)‐1,2‐C2B10H11}] (M=Ir ( 1 a ), Rh ( 1 b ); Cp*=η5‐C5Me5), [Cp*Ir(H){7‐(PPh2)‐7,8‐C2B9H11}] ( 2 a ), and [1‐(PPh2)‐3‐(η5‐Cp*)‐3,1,2‐MC2B9H10] (M=Ir ( 3 a ), Rh ( 3 b )) can be all prepared directly by the reaction of 1‐(PPh2)‐1,2‐C2B10H11 with dimeric complexes [(Cp*MCl2)2] (M=Ir, Rh) under different conditions. Compound 3 b was treated with AgOTf (OTf=CF3SO3?) to afford the tetranuclear metallacarborane [Ag2(thf)2(OTf)2{1‐(PPh2)‐3‐(η5‐Cp*)‐3,1,2‐RhC2B9H10}2] ( 4 b ). The arylphosphine group in 3 a and 3 b was functionalized by elemental sulfur (1 equiv) in the presence of Et3N to afford [1‐{(S)PPh2}‐3‐(η5‐Cp*)‐3,1,2‐MC2B9H10] (M=Ir ( 5 a ), Rh ( 5 b )). Additionally, the 1‐(PPh2)‐1,2‐C2B10H11 ligand was functionalized by elemental sulfur (2 equiv) and then treated with [(Cp*IrCl2)2], thus resulting in two 16‐electron complexes [Cp*Ir(7‐{(S)PPh2}‐8‐S‐7,8‐C2B9H9)] ( 6 a ) and [Cp*Ir(7‐{(S)PPh2}‐8‐S‐9‐OCH3‐7,8‐C2B9H9)] ( 7 a ). Compound 6 a further reacted with nBuPPh2, thereby leading to 18‐electron complex [Cp*Ir(nBuPPh2)(7‐{(S)PPh2}‐8‐S‐7,8‐C2B9H10)] ( 8 a ). The influences of other factors on structural transitions or the formation of targeted compounds, including reaction temperature and solvent, were also explored. 相似文献
Building upon our earlier results on the synthesis of electron‐precise transition‐metal–boron complexes, we continue to investigate the reactivity of pentaborane(9) and tetraborane(10) analogues of ruthenium and rhodium towards thiazolyl and oxazolyl ligands. Thus, mild thermolysis of nido‐[(Cp*RuH)2B3H7] ( 1 ) with 2‐mercaptobenzothiazole (2‐mbtz) and 2‐mercaptobenzoxazole (2‐mboz) led to the isolation of Cp*‐based (Cp*=η5‐C5Me5) borate complexes 5 a , b [Cp*RuBH3L] ( 5 a : L=C7H4NS2; 5 b : L=C7H4NOS)) and agostic complexes 7 a , b [Cp*RuBH2(L)2], ( 7 a : L=C7H4NS2; 7 b : L=C7H4NOS). In a similar fashion, a rhodium analogue of pentaborane(9), nido‐[(Cp*Rh)2B3H7] ( 2 ) yielded rhodaboratrane [Cp*RhBH(L)2], 10 (L=C7H4NS2). Interestingly, when the reaction was performed with an excess of 2‐mbtz, it led to the formation of the first structurally characterized N,S‐heterocyclic rhodium‐carbene complex [(Cp*Rh)(L2)(1‐benzothiazol‐2‐ylidene)] ( 11 ) (L=C7H4NS2). Furthermore, to evaluate the scope of this new route, we extended this chemistry towards the diruthenium analogue of tetraborane(10), arachno‐[(Cp*RuCO)2B2H6] ( 3 ), in which the metal center possesses different ancillary ligands. 相似文献
By treating cyclodextrin(CD) with methylaluminoxane (MAO such as PMAO or MMAO) or trimethylaluminium (TMA) followed by Cp2ZrCl2, CD/PMAO/Cp2ZrCl2, CD/MMAO/Cp2ZrCl2 and CD/TMA/Cp2ZrCl2 catalysts were prepared. The catalysts were analyzed by 13C-CP/MAS NMR spectrometer and ICP to examine the structure of catalyst and content of Zr and Al. Ethylene polymerization was conducted with MAO or TMA as cocatalyst. Styrene polymerization was also carried out with α-CD/MMAO/Cp*TiCl3 and α-CD/TMA/Cp*TiCl3 catalysts. While the ordinary trialkylaluminium such as TMA as well as MAO can be used as cocatalyst for ethylene polymerization, only MAO could initiate the styrene polymerization with α-CD supported catalysts. 相似文献
A series of binuclear complexes [{Cp*Ir(OOCCH2COO)}2(pyrazine)] ( 1 b ), [{Cp*Ir(OOCCH2COO)}2(bpy)] ( 2 b ; bpy=4,4′‐bipyridine), [{Cp*Ir(OOCCH2COO)}2(bpe)] ( 3 b ; bpe=trans‐1,2‐bis(4‐pyridyl)ethylene) and tetranuclear metallamacrocycles [{(Cp*Ir)2(OOC‐C?C‐COO)(pyrazine)}2] ( 1 c ), [{(Cp*Ir)2(OOC‐C?C‐COO)(bpy)}2] ( 2 c ), [{(Cp*Ir)2(OOC‐C?C‐COO)(bpe)}2] ( 3 c ), and [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](pyrazine)}2] ( 1 d ), [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](bpy)}2] ( 2 d ), [{(Cp*Ir)2[OOC(H3C6)‐N?N‐(C6H3)COO](bpe)}2] ( 3 d ) were formed by reactions of 1 a – 3 a {[(Cp*Ir)2(pyrazine)Cl2] ( 1 a ), [(Cp*Ir)2(bpy)Cl2] ( 2 a ), and [(Cp*Ir)2(bpe)Cl2] ( 3 a )} with malonic acid, fumaric acid, or H2ADB (azobenzene‐4,4′‐chcarboxylic acid), respectively, under mild conditions. The metallamacrocycles were directly self‐assembled by activation of C? H bonds from dicarboxylic acids. Interestingly, after exposure to UV/Vis light, 3 c was converted to [2+2] cycloaddition complex 4 . The molecular structures of 2 b , 1 c , 1 d , and 4 were characterized by single‐crystal x‐ray crystallography. Nanosized tubular channels, which may play important roles for their stability, were also observed in 1 c , 1 d , and 4 . All complexes were well characterized by 1H NMR and IR spectroscopy, as well as elemental analysis. 相似文献
Six examples of newly synthesized α,α’-bis (aryl)-2,3:5,6-bis (pentame thylene)pyridyliron complexes [2,3:5,6-{C4H8C(NAr)}2C5HN]FeCl2 (Ar = 2-(c-C5H9)-6-MeC6H3 Fe1 , 2-(c-C6H11)-6-MeC6H3 Fe2 , 2-(c-C8H15)-6-MeC6H3 Fe3 , 2-(c-C5H9)-4,6-Me2C6H2 Fe4 , 2-(c-C6H11)-4,6-Me2C6H2 Fe5 , 2-(c-C8H15)-4,6-Me2C6H2 Fe6 ; c refers as cyclic), on activation with methylalumoxane (MAO) or modified MAO (MMAO), exhibit high activities towards ethylene polymerization, producing strictly linear polyethylenes with terminal vinyl groups. The catalytic performances are systematically investigated along with various polymerization parameters as well as the microstructures of resultant polyethylenes. The steric hindrances of ortho-cycloalkyl substituents of Nimino-aryl groups significantly affect the activities of the corresponding iron precatalysts as well as the microstructures of resultant polyethylenes: higher steric hindrance the ortho-cycloalkyl substituents, higher activity the iron precatalyst, lower molecular weight the resultant polyethylenes. Experimental observations are additionally supported by the computational study. The resultant polyethylenes exhibited excellent hydrophobicity. 相似文献
(Phosphinoamide)(cyclopentadienyl)titanium(IV) complexes of the type Cp*TiCl2(η2-Ph2PNR) [Cp*=C5Me5; R = t-Bu (2a), R = n-Bu (2b), R = Ph (2c)] have been prepared by the reaction of Cp*TiCl3 with the corresponding lithium phosphinoamides. The structure of Cp*TiCl2(η2-Ph2PNtBu) (2a) and Cp*TiCl2(η2-Ph2PNPh) (2c) have been determined by X-ray crystallography. These complexes exhibited moderate catalytic activities for ethylene polymerization in the presence of modified methylaluminoxane (MMAO). Catalytic activity of up to 2.5 × 106 g/(mol Ti h) was observed when activated by i-Bu3Al/Ph3CB(C6F5)4. 相似文献
The reaction of the neutral carborane C2B9H13 with Cp*M(CH3)3 (M = Zr (a), Hf (b); Cp* = η5-C5Me5) yields [Cp(C2B9H11)M(CH3)]n (3a, b). Complexes 3a, b form THF adducts Cp*(C2B9H11)M(CH3)(THF) 4, insert 2-butyne to yield Cp*(C2B9H11)M{C(Me=CMe2} 5, and undergo methane elimination upon thermolysis to yield methylene-bridged complexes [Cp*(C2B9H11)M]2(μ-CH2) (6). These chemical studies, and companion structural and theoretical studies establish that 3a, b are neutral analogues of the cationic Cp2M(R)+ species (1; Cp = η5-C5H5) and Cp2M(R)(L)+ (2) which are believed to be active in Cp2MX2-based Ziegler catalysts. Despite the lower metal charge, 3–6 exhibit characteristic “electrophilic metal alkyl” properties including agostic M-H-C and M-H-B interactions, high insertion and intramolecular C-H activation reactivity, and high ethylene polymerization and propene oligomerization activity. These observations suggest that the key requirement for high insertion/polymerization activity in metallocene systems is high metal unsaturation (i.e. two empty metal-centered orbitals) rather than charge. 相似文献