Patent Application: US-43570609-A

Abstract:
metal - ligand combination initiators are provided which yield organometallic complexes capable of the polymerization of olefins to high molecular weight polymers . additionally , these initiators also enable the copolymerization of olefins with functionalized comonomers . these organometallic complexes comprise of a late transition metal with a neutral chelating ligand that contains a lewis basic functionality in conjugation with an electronically delocalized conduit extending from the metal to the functionality . this structural feature results in a highly active complex , which generates high molecular weight polymers with unique microstructures . under particular conditions , the organometallic complexes provide for the living polymerization of monomers and comonomers .

Description:
novel organometallic initiator complexes are provided that are capable of polymerizing olefins or copolymerizing olefins with functionalized comonomers to yield high molecular weight polymers (≧ 5 , 000 ). where r , r ′, r ″ and r ′″ are each independently an achiral or chiral alkyl or aryl group with or without one or more functional groups ; m is fe , co , ni or pd ; x is an alkyl , hydride or halide group ; and l is o , n — r ″″, s , or ═ ch 2 , where r ″″ is an alkyl or aryl group . in particular embodiments , the initiator is 2 , 4 - bis ( 2 , 6 - diisopropylphenylimino ) pentan - 3 - one nickel dibromide or 2 , 4 - bis ( 2 - isopropyl - 6 - methylphenylimino ) pentan - 3 - one nickel dibromide . the term “ alkyl ” refers to a branched or unbranched saturated hydrocarbyl group such as methyl , ethyl , n - propyl , isopropyl , n - butyl , isobutyl , t - butyl , octyl , decyl , and the like , as well as cycloalkyl groups such as cyclopentyl , cyclohexyl and the like . in particular embodiments , an alkyl group can be c 1 - 30 or c 1 - 20 . the term “ aryl ” refers to an aromatic hydrocarbyl group containing a single aromatic ring or multiple aromatic rings that are fused together , linked covalently , or linked to a common group such as a methylene or ethylene moiety . in some embodiments , aryl groups contain one aromatic ring or two fused or linked aromatic rings , e . g ., phenyl , naphthyl , biphenyl , diphenylether , diphenylamine , benzophenone , and the like . in particular embodiments , an aryl group including any substituents can have from 4 to 50 carbon atoms , 4 to 40 carbon atoms , 4 to 30 carbon atoms , 4 to 20 carbon atoms , or 4 to 10 carbon atoms , or more particularly , can have from 6 to 50 carbon atoms , 6 to 40 carbon atoms , 6 to 30 carbon atoms , 6 to 20 carbon atoms or 6 to 10 carbon atoms . the term “ alkoxy ” refers to an alkyl group bound through a single , terminal ether linkage ; that is , an alkoxy group may be represented as — o - alkyl , where alkyl is as defined above . an alkyl group or an aryl group can be substituted with a functional group . as used herein , the term “ substituted ” in connection with a hydrocarbyl group refers to a hydrocarbyl group in which at least one hydrogen atom bound to a carbon atom is replaced with one or more substituents . for example , a disubstituted aryl group , such as a diisopropylphenyl group , has two substituents replacing two hydrogen atoms of the parent aryl group . a substituent can be a “ functionality ” or “ functional group ” such as , but not limited to , halo , ester , keto ( oxo ), amino , imino , hydroxyl , carboxyl , phosphite , phosphonite , phosphine , phosphinite , thioether , amide , nitrile , and ether . for example , methyl acrylate can be considered a hydrocarbyl substituted with a carboxyl functional group . in particular embodiments , an alkyl or aryl group can have one , two , three , four , or more than four , substituents . in the complex of formula ( i ), r , r ′, r ″ and r ′″ can each independently be an achiral or chiral hydrocarbyl group . as is known , the term “ chiral ” refers to molecules which have the property of non - superimposability on their mirror image partner , while the term “ achiral ” refers to molecules which are superimposable on their mirror image partner . initiators can be prepared by combining a ligand with an appropriate metal . in some embodiments , the initiators are prepared via a reaction sequence , as shown in example 1 ( below ). a general formula ( ii ) of such a ligand is as follows : where r , r ′, r ″ and r ′″ are each independently an achiral or chiral alkyl or aryl group with or without one or more functional groups , and l is o , n — r ″″, s , or ═ ch 2 , with r ″″ being an alkyl or aryl group . initiators of the present invention can polymerize and / or copolymerize one or more of the following olefins : r 1 ch ═ ch 2 , cyclopentene , styrene , norbornene ; substituted cyclopentene , styrene or norbornene derivatives bearing one or more functional groups ; or a polar olefin of the formula h 2 c ═ cr 2 x ; where r 1 is either hydrogen , an alkyl group , or an alkyl group substituted with one or more functional groups , r 2 is hydrogen , an alkyl group , an aryl group or an alkoxy group , and x is a polar group . in these embodiments , r 1 can be hydrogen , alkyl , or a substituted alkyl bearing one or more functional groups ( such as , — oh , — nh 2 , cn , — coor , — ocor , — c ( o ) r , or — c ( o ) nrr ′, where r and r ′ are each independently hydrogen or an alkyl group ). examples of x include , but are not limited to : a halogen such as cl , br , or f ; — cn ; — c 6 h 5 n ; — conr 3 r 4 ; — or 3 ; — coor 3 ; — ocor 3 ; — c 6 h 5 or 3 ; — cor 3 and / or — c 6 h 5 nr 3 r 4 ; wherein r 3 and r 4 are each independently hydrogen or an alkyl group , which can be a c 1 - 12 alkyl group . additionally , the polar olefin can be h 2 c ═ ch ( ch 2 ) n co 2 r 5 , where r 5 is hydrogen or an alkyl group , and n is between 0 and 20 . polymers generated in connection with these initiators can exhibit a unique microstructure . polymerizations can occur at temperatures from at or about − 100 ° c . to at or about 250 ° c . the preferred range is at or about 60 ° c . to at or about 200 ° c . using such polymerizations conditions , with ethylene or propylene , high molecular weight polymers with a unique architecture can be produced ( as in examples 2 and 3 , below ). in another embodiment , these initiators can be used for copolymerization of ethylene with functionalized comonomers ( as in example 4 , below ) or other 1 - alkenes . co - catalysts can be used with the above initiators for polymerization / copolymerization reactions . such co - catalysts include , but are not limited to , any alkylaluminum , alkylaluminoxane , and borate co - catalyst known in the art . such co - catalysts include , but are not limited to , methylaluminoxane ( mao ), modified methylaluminoxane type - 3a , or trimethylaluminum ( tma ). in certain embodiments with the initiator complex of formula ( i ), polymerization can occur under conditions that result in a living polymerization process . in these embodiments , a single monomer can be polymerized in a living manner , or more than one monomer can undergo living polymerization . by adjusting conditions such as temperature and pressure , living polymerization can occur so that the growth of m n of the polymer as a function of time is linear . under living conditions , molecular weight distributions that are symmetric and polymers with pdi values of less than or equal to 1 . 3 can be obtained . using living conditions , block copolymers , including diblock , triblock and other multiblock copolymers , can be prepared . for example , under living polymerization conditions , a first monomer can be polymerized to produce a polymer product , and then a second monomer can be added to the polymer product to produce a block copolymer . in addition , tapered , regioblock and / or end functionalized polymers can be prepared . polymerization under living conditions can also yield semicrystalline polymers such as semicrystalline polyethylene or polypropylene . the term “ semicrystalline ” refers to polymers that have both a crystalline portion and an amorphous portion . polymerization under living conditions can also yield amorphous polymers . the present invention may be better understood by referring to the accompanying examples , which are intended for illustration purposes only and should not in any sense be construed as limiting the scope of the invention as defined in the claims appended hereto . initiator 1 is synthesized from the ligand , 2 , 4 - bis ( 2 , 6 - diisopropylphenylimino ) pentan - 3 - one . this ligand can be made according the following scheme and procedure . [ cu ii ( 1 )( aco )]. to a solution of cu ii ( ch 3 coo ) 2 — h 2 o ( 2 . 38 g ) in ch 3 oh — ch 2 cl 2 ( v / v = 1 : 1 , 500 ml ) was added drop - wise a solution of 1 ( 5 g ) in ch 2 cl 2 ( 20 ml ) while stirring at room temperature . after stirring the mixture overnight , the solvent was removed in vacuo . the resulting brown material was dissolved in ch 2 cl 2 ( 100 ml ) and extracted with water three times ( 100 ml × 3 ). the solvent was removed in - vacuo and the brown solid was washed with water and collected by filtration onto a fritted funnel and dried under high vacuum overnight ( 5 . 5 g , 84 . 9 %). [ cu ii ( 1 ) aco ] ( 5 g ) was treated in methanol ( 1000 ml ) at 50 ° c . in a 3 neck round bottom flask capped with two septa and a reflux condenser attached to an oil bubbler . oxygen was vigorously bubbled through the solution for 72 hours or until a complete color change from brown to purple was noted . at this point oxygen was bubbled through for another 12 hours and the volume was reduced to 100 ml by bubbling oxygen through at 50 ° c . the methanol solution was cooled by allowing to stand at room temperature , overnight , under an atmosphere of oxygen . purple crystals were collected by filtration . 2 , 4 - bis ( 2 , 6 - diisopropylphenylimino ) pentan - 3 - one ( 3 g , 75 . 2 %) was isolated by treating the purple crystals with aqueous nh 3 . removal of the solvent gave a pale yellow solid . the synthesis of initiator 1 was carried out under an inert atmosphere according to scheme 1 . all reagents were dried , by various methods , prior to use . to a stirring suspension of ( 1 , 2 - dimethoxyethane ) nibr 2 complex ( 71 . 1 mg , 0 . 231 mmol ) in 15 ml methylene chloride , 2 , 4 - bis ( 2 , 6 - diisopropylphenylimino ) pentan - 3 - one ( 100 mg , 0 . 231 mmol ), in 5 ml methylene chloride , was added at once , at room temperature . shortly after the addition of the ligand , the solution began to turn red . the suspension was allowed to stir for an additional 2 . 5 hours at room temperature . the reaction mixture was then filtered through celite and the solvent removed in - vacuo . the corresponding red powder was washed with cold diethyl ether (− 35 ° c ., 3 ×, 10 ml ), dried , resuspended in methylene chloride ( 10 ml ), refiltered through celite and then dried to give the pure compound as a red powder in 49 . 0 % yield ( 73 . 7 mg , 0 . 113 mmol ). anal . calc . ( c 29 h 40 n 2 ) c , 53 . 49 ; h , 6 . 19 ; n , 4 . 30 . found : c , 53 . 71 ; h , 6 . 24 ; n , 4 . 23 . single crystals were obtained from a concentrated solution in methylene chloride at − 35 ° c . the molecular connectivity is consistent with an n , n - coordinated structure in which the ligand is bound as a neutral donor . bond distances within the six membered chelate ring are consistent with the structure drawn in scheme 1 as illustrated by the following selected bond lengths ( a ): c ( 4 )- n ( 2 ) 1 . 291 , c ( 3 )- c ( 4 ) 1 . 518 , c ( 2 )- n ( 1 ) 1 . 288 , c ( 2 )- c ( 3 ) 1 . 511 and c ( 3 )- o ( 1 ) 1 . 222 . the ni ( ii ) atom adopts a pseudotetrahedral coordination geometry with a contact shifted 1 h - nmr exhibiting relatively narrow line widths at room temperature . the six membered chelate ring adopts a boat conformation . see fig1 for the ortep drawing of initiator 1 . homopolymerizations of ethylene were conducted in the following manner using initiator 1 . a 300 ml steel autoclave reactor , equipped with an addition funnel was loaded , inside a glovebox with initiator 1 in 90 ml of toluene . methylaluminoxane ( aldrich , 10 wt . % in toluene ) ( mao ) was added to the addition funnel followed by toluene so that the final volume was 10 ml . the reactor was sealed inside the glovebox and attached to an ethylene line . the reactor was pre - pressurized with ethylene . the mao solution was then injected under a specified pressure of ethylene , which was fed continuously at that pressure over the course of the reaction . ethylene was vented after a specified amount of time and acidified methanol ( 10 % hcl ) was added to quench the polymerization . the precipitated polymer was collected by filtration , washed copiously with methanol , followed by acetone and dried under high vacuum overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). polymer melting points were measured on a ta instruments differential scanning calorimeter , ( model dsc 2920 ) at a rate of 10 ° c ./ min for three cycles using a temperature range of 0 - 180 ° c . the optimal amount of co - catalyst ( mao ) was determined as shown in fig3 . table 1 shows selected polymerization data . table 1 illustrates the relationship between temperature and activity . the activity increases dramatically with temperature , however , only mass transfer limited rates could be obtained above 40 ° c . the polymer produced exhibits high molecular weights (& gt ; 1 × 10 6 ) with relatively short reaction times ( ca . 10 min ). the polymers produced have melting points between 80 and 125 ° c . homopolymerizations of propene were conducted in the following manner using initiator 1 . a 300 ml steel autoclave reactor , equipped with an addition funnel was loaded , inside a glovebox with initiator 1 in 90 ml of toluene . mao ( aldrich , 10 wt . % in toluene ) was added to the addition funnel followed by toluene so that the final volume was 10 ml . the reactor was sealed inside the glovebox and attached to a propene line . the reactor was pre - pressurized with propene . the mao solution was then injected under a specified pressure of propene , which was fed continuously at that pressure over the course of the reaction . ethylene was vented after a specified amount of time and acidified methanol ( 10 % hcl ) was added to quench the polymerization . the precipitated polymer was collected by filtration , washed copiously with methanol , followed by acetone and dried under high vacuum overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). glass transitions ( t g ) and melting temperatures ( t m ) were measured on a ta instruments differential scanning calorimeter , ( model dsc 2920 ) at a rate of 5 ° c ./ min for three cycles using a temperature range of − 70 - 180 ° c . 13 c nmr spectra of the polymers was obtained in 1 , 1 , 2 , 2 - tetrachloroethane - d 2 at room temperature . table 2 ( below ) shows selected polymerization data . the polypropylene produced is mainly amorphous with t g s ranging from − 35 ° c . to − 20 ° c . depending on the reaction temperature . entry 1 , 2 and 4 exhibit the following tacticity as illustrated in table 3 , below . the inherent differences in the microstructure of the polypropylene produced at different temperatures illustrates that these catalysts allow for microstructure control in the final product through variations in temperature , pressure , monomer concentration and other various reaction conditions . additionally variations in the ligand are expected to give further control and substantial stereoregularity . the presence of a melting point t m = 150 ° c . and t c = 117 ° c . in entry 3 illustrates that polypropylene obtained with initiator 1 exhibits some crystallinity . copolymerizations of ethylene and methyl acrylate were conducted in the following manner using initiator 1 . a 300 ml steel autoclave reactor , equipped with an addition funnel was loaded , inside a glovebox with initiator 1 in 90 ml of toluene . mao ( aldrich , 10 wt . % in toluene ) was added to the addition funnel along with a specified amount of neat methyl acrylate , followed by toluene so that the final volume was 10 ml . the reactor was sealed inside the glovebox and attached to an ethylene line . the reactor was pre - pressurized with ethylene . the mao - methyl acrylate solution was then injected under a specified pressure of ethylene , which was fed continuously at that pressure over the course of the reaction . ethylene was vented after a specified amount of time and acidified methanol ( 10 % hcl ) was added to quench the polymerization . the precipitated polymer was collected by centrifugation , washed copiously with methanol , followed by thf , and dried under high vacuum overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). 1 h nmr spectra of the polymers was obtained in 1 , 1 , 2 , 2 - tetrachloroethane - d 2 at 115 ° c . addition of methyl acrylate to the reaction resulted in significantly lowered activities , however , random copolymers with low levels of incorporation were generated . better control over the final product through variations in reaction conditions and initiator structure are expected to improve the yield , activity , control and incorporation . entry 1 , table 4 , exhibits a characteristic ( c ═ o ) stretch in the ir spectrum , however , the incorporation is not detectable by 1 h - nmr . at reduced ethylene pressures and elevated methyl acrylate concentrations , the incorporation is higher ( entry 2 ). fig2 , shows the ir spectra for entry 1 and 2 . homopolymerizations of ethylene were conducted in the following manner using initiator 1 . a 2000 ml steel autoclave reactor , equipped with an addition straw was heated in an oven at 150 ° c . overnight . the reactor was assembled , while hot and purged with nitrogen and pumped down a total of three times . the reactor was then sealed under nitrogen . a specified amount of solvent and co - catalyst were added using standard schlenk and air - free techniques . a stock solution of the initiator was prepared and added to the addition straw under a stream of nitrogen . the reactor was sealed and attached to an ethylene line . the reactor was pre - pressurized with ethylene . the initiator solution was then injected under a specified pressure of ethylene , which was fed continuously at that pressure over the course of the reaction . 10 ml ethanol was added to quench the polymerization . the precipitated polymer was collected by filtration , washed copiously with acidified methanol ( 10 % hcl ); then washed with methanol followed by acetone and dried in a vacuum oven overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). polymer melting points were measured on a ta instruments differential scanning calorimeter , ( model dsc 2920 ) at a rate of 10 ° c ./ min for three cycles using a temperature range of 0 - 180 ° c . fig4 shows selected polymerization data obtained from the homopolymerization of ethylene , and illustrates the following . the ethylene consumption is consistent over the course of 30 minutes . the activity is significantly higher when mmao - 3a is used as a co - catalyst versus mao . the activity increases significantly with temperature ; up to 22800 kg p / mol ni hr at 50 ° c . ( reaction 17 ). ethylene consumption is consistent for 30 minutes at 75 ° c . ( reaction 11 ) illustrating the catalytic species is robust toward decomposition at elevated temperatures . additionally , the catalytic species is highly active in the presence of h 2 ( reaction 13 ). melt flow rates of the polymer obtained in reaction 13 also suggest that h 2 acts as a chain transfer agent . copolymerizations of ethylene and methyl or t - butyl acrylate were conducted in the following manner using initiator 1 . a 2000 ml steel autoclave reactor , equipped with an addition straw was heated in an oven at 150 ° c . overnight . the reactor was assembled , while hot and purged with nitrogen and pumped down a total of three times . the reactor was then sealed under nitrogen . a specified amount of solvent , co - catalyst and acrylate were added using standard schlenk and air - free techniques . acrylate was added to give 0 . 082 m solution in reaction 14 and 15 . a stock solution of the initiator was prepared and added to the addition straw . the reactor was sealed and attached to an ethylene line . the reactor was pre - pressurized with ethylene . the initiator solution was then injected under a specified pressure of ethylene , which was fed continuously at that pressure over the course of the reaction . 10 ml ethanol was added to quench the polymerization . the precipitated polymer was collected by filtration , washed copiously with acidified methanol ( 10 % hcl ); then washed with methanol followed by acetone and dried in a vacuum oven overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). 1 h and 13c nmr spectra of the polymers was obtained in 1 , 1 , 2 , 2 - tetrachloroethane - d 2 at 115 ° c . fig5 shows the results of copolymerizations using ethylene and acrylates . the figure illustrates that the copolymerization of ethylene and methyl acrylate proceeds with good activity in the presence of mmao at 50 ° c . and 3 . 0 mpag . the incorporation of methyl acrylate was 0 . 14 mol % in reaction 14 . compared to the smaller scale reactions this illustrates that the choice of co - catalyst and reaction conditions are important for activity , incorporation and polymer microstructure . under the same conditions , the copolymerization of ethylene and tert - butyl acrylate showed lower activity and less incorporation . no incorporation was detectable by nmr for reaction 15 , however , a peak corresponding to the ( c ═ o ) stretch was observed in the ir spectrum of the copolymer generated . copolymerizations of ethylene and 1 - hexene were conducted in the following manner using initiator 1 . a 2000 ml steel autoclave reactor , equipped with an addition straw was heated in an oven at 150 ° c . overnight . the reactor was assembled , while hot and purged with nitrogen and pumped down a total of three times . the reactor was then sealed under nitrogen . a specified amount of solvent , co - catalyst and 50 ml 1 - hexene were added using standard schlenk and air - free techniques . a stock solution of the initiator was prepared and added to the addition straw . the reactor was sealed and attached to an ethylene line . the reactor was pre - pressurized with ethylene . the initiator solution was then injected under a specified pressure of ethylene , which was fed continuously at that pressure over the course of the reaction . 10 ml ethanol was added to quench the polymerization . the precipitated polymer was collected by filtration , washed copiously with acidified methanol ( 10 % hcl ); then washed with methanol followed by acetone and dried in a vacuum oven overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). 1 h and 13 c nmr spectra of the polymers was obtained in 1 , 1 , 2 , 2 - tetrachloroethane - d 2 at 115 results of the above copolymerization reactions of ethylene and 1 - hexene are shown in fig6 . the figure illustrates that reaction 16 showed a high activity , consistent with a rate increase in the copolymerization reaction . although temperature control was not maintained , based on the presence of additional butyl and long chain branching the incorporation of 1 - hexene was calculated to be 0 . 32 mol %. this illustrates that ethylene and 1 - hexene can be copolymerized with high activities . the synthesis of initiator 2 was carried out according to scheme 2 under an inert atmosphere . all reagents were dried , by various methods , prior to use . to a stirring suspension of ( 1 , 2 - dimethoxyethane ) nibr 2 complex ( 82 . 0 mg , 0 . 266 mmol ) in 15 ml methylene chloride , 2 , 4 - bis ( 2 - isopropyl - 6 - methylphenylimino ) pentan - 3 - one ( 100 mg , 0 . 266 mmol ) ( prepared in a procedure similar to that shown in example 1 ), in 5 ml methylene chloride , was added at once , at room temperature . shortly after the addition of the ligand , the solution began to turn red . the suspension was allowed to stir for an additional 2 . 5 hours at room temperature . the reaction mixture was then filtered through celite and the solvent removed in vacuo . the corresponding red powder was washed with cold diethyl ether (− 35 ° c ., 3 ×, 10 ml ), dried , resuspended in methylene chloride ( 10 ml ), refiltered through celite and then dried to give the pure compound as a red powder in 82 . 0 % yield ( 130 . 0 mg , 0 . 218 mmol ). anal . calc . ( c 25 h 32 n 2 ) c , 50 . 46 ; h , 5 . 42 ; n , 4 . 71 . found : c , 52 . 38 ; h , 5 . 67 ; n , 4 . 80 . homopolymerizations of ethylene were conducted in the following manner using initiator 2 . a 300 ml steel autoclave reactor , equipped with an addition funnel was loaded , inside a glovebox with initiator 2 in 90 ml of toluene . mao ( aldrich , 10 wt . % in toluene ) was added to the addition funnel followed by toluene so that the final volume was 10 ml . the reactor was sealed inside the glovebox and attached to an ethylene line . the reactor was pre - pressurized with ethylene . the mao solution was then injected under a specified pressure of ethylene , which was fed continuously at that pressure over the course of the reaction . ethylene was vented after a specified amount of time and acidified methanol ( 10 % hcl ) was added to quench the polymerization . the precipitated polymer was collected by filtration , washed copiously with methanol , followed by acetone and dried under high vacuum overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). polymer melting points were measured on a ta instruments differential scanning calorimeter , ( model dsc 2920 ) at a rate of 10 ° c ./ min for three cycles using a temperature range of 0 - 180 ° c . table 5 below shows selected polymerization data . homopolymerizations of propene were conducted in the following manner using initiator 2 . a 300 ml steel autoclave reactor , equipped with an addition funnel was loaded , inside a glovebox with initiator 2 in 90 ml of toluene . mao ( aldrich , 10 wt . % in toluene ) was added to the addition funnel followed by toluene so that the final volume was 10 ml . the reactor was sealed inside the glovebox and attached to a propene line . propene was condensed for five minutes at 0 ° c . the reactor was then cooled to the desired temperature and the mao solution was then injected . propene was vented after a specified amount of time and acidified methanol ( 10 % hcl ) was added to quench the polymerization . the precipitated polymer was collected by centrifugation , washed copiously with methanol , followed by acetone and dried under high vacuum overnight . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a polymer laboratories , high - temperature chromatograph , pl - gpc 200 ). glass transitions ( t g ) and melting temperatures ( t m ) were measured on a ta instruments differential scanning calorimeter , ( model dsc 2920 ) at a rate of 5 ° c ./ min for three cycles using a temperature range of − 70 - 180 ° c . table 6 below shows selected polymerization data . fig7 shows a differential scanning calorimetry generated graph for entry 2 in table 6 above . the melting temperature ( t m ) and corresponding crystallization temperature ( t c ) indicate the transition from a purely amorphous polymer to a polymer with some crystallinity based on the symmetry of the ligand and the reaction conditions . this illustrates that the microstructure can be controlled based on the choice of ligand and the corresponding reaction conditions . in order to illustrate the importance of the ketone functionality on the ligand the following comparative example is included . complex 5 ( arn ═ c -( me ) ch 2 c ( me )= nar ] nibr 2 where ar = 2 , 6 - diisopropylphenyl ) ( 46 ) is the corresponding β - diimine complex of ni ( ii ) lacking a ketone functionality on the backbone ( c ( 3 ) in fig1 ). complex 5 is a precursor for ethylene polymerization differing from that catalyzed by the analogous α - diimine complex ( i . e . [ arn ═ c -( me ) c ( me )= nar ] nibr 2 where ar = 2 , 6 - diisopropylphenyl ) in two significant ways : the polyethylene produced is more linear and complex 5 is a less active catalyst pre - cursor . in the reported example , a 100 ml autoclave reactor was charged with complex 5 ( 52 mg , 0 . 080 mmol ) and flushed with ethylene . a solution of modified methyl aluminoxane ( 2 . 40 ml , 6 . 4 wt % al in toluene from akzo , 4 . 88 mmol ) in 40 ml of toluene under nitrogen was then added . the reactor was pressurized with 280 psi of ethylene and stirred for 3 . 5 hr . the reaction temperature increased from 27 to 31 ° c . during this time and work - up afforded 4 . 07 g pe . ( t m 120 . 2 ° c .). no molecular weight data was included . this corresponds to an activity of 14 . 5 ( kg p / mol ni hr ). polymerization of ethylene by complex arn ═ c ( me )- c ( me )= nar ) nibr 2 ( ar = 2 , 6 - diisopropyl )/ mao at 25 ° c . was accomplished by adding standard catalyst solution ( 1 . 7 μmol catalyst ) to a schlenk flask which contained 100 ml toluene and was under 1 atmosphere of ethylene pressure . the solution was brought to the desired temperature and 1 . 0 ml of a 10 % solution of mao (˜ 1000 eq ) in toluene was added . the solution was stirred for 15 minutes . polymer began to precipitate within minutes . the polymerization was quenched and the polymer precipitated from acetone . the resulting polymer was dried in vacuo to give 4 . 6 g pe . m w = 7 . 6 × 10 − 4 , m n = 3 . 1 × 10 − 4 . activity = 11000 kg of pe mol − 1 of ni h − 1 . examples 12 - 15 relate to living polymerization reactions . example 12 describes the results of polymerization reactions , while examples 13 - 15 provide supporting information for the results described in example 12 . starting with the previously reported reactivity of initiator 1 / mao , the polydispersity ( pdi ) of the pe products was noted to decrease with decreasing reaction temperature ( t rxn ) ( 57 ). to assess whether the active species could polymerize ethylene in a living manner , the volatiles from commercially available mao were removed in vacuo until a free flowing white powder was obtained . this treatment is commonly utilized to remove free tma , which may participate in termination and chain transfer reactions ( 58 ). a series of polymerizations were carried out to probe the effect of t rxn and ethylene pressure ( p c2h4 ). in these reactions , a 100 ml autoclave reactor was loaded with 40 ml toluene and mao so that [ al ]/[ ni ]= 250 . a stock solution of initiator 1 was prepared and 1 . 5 μmol of initiator ( 1 ) in approximately 1 ml ch 2 cl 2 was added to an addition funnel . the reactor and addition funnel were pre - pressurized with ethylene , cooled to the appropriate temperature , and the polymerization was initiated by introducing initiator ( 1 ) under rapid stirring conditions . ethylene was continually fed into the reactor over the course of the polymerization , and the reaction terminated by quenching with methanol or triethylsilane . table 7 summarizes the results of the initial screening study . comparison of entries 1 and 2 demonstrates that reducing t rxn from 20 ° c . to 10 ° c . while keeping p c2h4 constant at 300 psi leads to a narrowing of the pdi ( 1 . 60 vs . 1 . 35 ), as determined by gel permeation chromatography ( gpc ) calibrated against polystyrene standards . reducing p c2h4 to 150 psi at t rxn = 10 ° c ., leads to further narrowing of the pdi to 1 . 22 , as shown in entry 3 . at t rxn =− 10 ° c . at p c2h4 = 150 psi , a pe with pdi = 1 . 09 was obtained ( entry 4 ). under the same conditions , when the polymerization is allowed to proceed for 20 minutes instead of 10 minutes , the molecular weight increases by approximately a factor of two ( entry 4 vs . 5 ). entry 6 shows that reducing p c2h4 to 50 psi yields a pe with properties nearly identical to those obtained with p c2h4 = 150 psi ( entry 4 ) in terms of pdi , number average molecular weight ( m n ) and melting point ( t m ), but with a more symmetric gpc peak shape than in entry 4 ( see examples 13 . . . , below ). the effect of the quenching agent and method is demonstrated by comparing entry 6 ( methanol ) with entry 7 ( triethylsilane ). while the data in table 7 show that the product properties are indistinguishable , the gpc traces after quenching with methanol contain a small shoulder of high molecular weight product , which is absent after quenching with triethylsilane . for this reason , triethylsilane was utilized in subsequent reactions . entry 8 shows that excellent control over the molecular weight characteristics can be obtained after 60 minutes ; the reaction scheme and gpc trace of this product are shown in fig8 a and 8b , respectively . this pe displays a melting temperature ( t m ) of 122 ° c . and a crystallinity ( χ c ) of 32 %, despite the low ethylene pressure ( p c2h4 = 50 psi ). fig9 shows a plot of m n versus time under the same conditions as in entry 7 ( m n (▪) and pdi ( x ) versus time using initiator 1 / mao at − 10 ° c . for pe , pp and ph determined by gpc ). the linear growth of m n as a function of time and pdi values ≦ 1 . 10 , together with the results in table 7 , are consistent with the formation of semicrystalline pe under living conditions . the initiator 1 / mao combination can also be used to polymerize propene under living conditions . these reactions involved condensing 5 ml of propene into a 300 ml reactor loaded with 100 ml toluene and mao so that [ al ]/[ ni ]= 250 . the reaction was cooled to − 10 ° c . and the polymerization was initiated by the introduction of 10 μmol of initiator 1 . entry 9 in table 7 shows the results for the pp obtained after 120 minutes of reaction ; the gpc trace of this product is shown in fig8 b . aliquots taken over the course of the polymerization show a linear relationship of m n as a function of time , as shown in fig9 . these characteristics , coupled with pdi values below 1 . 06 , are indicative of a living polymerization . a melting transition was observed at t m = 59 ° c . and a degree of crystallinity of ˜ 9 %. reactions with 1 ′- hexene were carried out with [ 1 - hexene ]= 0 . 85 m under conditions similar to those in entry 9 . the polymerization was sampled over the course of the reaction and examination of the products shows a linear increase of m n versus time and low pdi values , as shown in fig9 . table 7 , entry 10 contains results for the polymer generated at 120 minutes ; the gpc trace of this product is shown in fig8 b . dsc analysis reveals that the polymer produced is amorphous ( t g =− 62 . 0 ° c .). the method described herein provides conditions that allow for the living polymerization of ethylene and α - olefins by using initiator 1 / mao . this is apparently the first late metal system that can polymerize ethylene in a living manner to afford semicrystalline pe , in contrast to quasi - living polymerization such as that in diamanti et al . ( 25 ). this excellent control is remarkable given the fact that the pe precipitates over the course of the reaction . additionally , it is interesting to note that the pp produced contains isotactic sequences . these results are in contrast to other late metal systems that generally yield amorphous and atactic pp in the absence of chiral ligands ( 54 ; also , for partially isotactic pp ([ mm ]= 0 . 41 ) using an α - diimine ni ( ii ) system , see pappalardo , d . et al . ( 63 )), or induce syndiotactic enchainment at lower temperatures ( 64 ). increasing the size of the monomer to 1 - hexene results in a loss of stereocontrol . all manipulations of air and / or water sensitive compounds were performed under an inert atmosphere using standard glove box and schlenk - line techniques . dichloromethane ( ch 2 cl 2 ) was distilled from cah 2 and 1 - hexene from na / k alloy . toluene was purchased from aldrich ( anhydrous grade ) and used as received . mao ( methylaluminoxane solution , 10 wt . % in toluene ) was purchased from aldrich and dried in vacuo , until a free flowing white powder was obtained . ethylene ( 99 . 99 %) and propene ( 99 . 97 %) were purchased from matheson trigas and purified by passing through agilent moisture and oxygen traps . initiator 1 was synthesized as previously reported ( 57 ). reagents , unless otherwise specified , were purchased from aldrich and used without further purification . polymerization activities were calculated from the mass of the product obtained . polymers were characterized by gpc analysis , relative to polystyrene standards , at 135 ° c . in o - dichlorobenzene ( in a varian polymer laboratories , high - temperature chromatograph , pl gpc 220 ). polymer melting points ( t m ) and glass transition temperatures ( t g ) were measured on a ta instruments differential scanning calorimeter ( model q - 20 ) at a rate of 10 ° c ./ min for three cycles using a temperature range of − 70 to 180 ° c . polymerization of ethylene : a 100 ml parr steel autoclave reactor , equipped with an addition funnel , was loaded inside a glovebox with toluene ( 40 ml ) and solid mao so that [ al ]/[ ni ]= 250 ( 22 mg , 0 . 375 mmol ). a stock solution of initiator 1 was prepared and 1 . 5 μmol of initiator 1 in approximately 1 ml ch 2 cl 2 was added to the addition funnel . in table 8 entry 8 , 0 . 75 μmol of initiator 1 in approximately 1 ml ch 2 cl 2 was added to the addition funnel . an [ al ]/[ ni ]= 250 ( 11 mg , 0 . 188 mmol ) was maintained in this reaction . the reactor was sealed inside the glovebox and attached to an ethylene line . the addition funnel was pre - pressurized with ethylene at 50 psi above the desired reaction pressure with ethylene . the reactor was pre - pressurized to ( p c2h4 ) with ethylene and cooled to the appropriate reaction temperature ( t rxn ). the polymerization was initiated via injection of the solution of initiator 1 and ethylene was continually fed into the reactor over the course of the reaction . the reaction temperature ( t rxn ) was controlled using a dry - ice / acetone bath and found to be ± 2 ° c . as monitored by an internal thermocouple . ethylene was vented after a specified amount of time , and methanol was added to quench the polymerization ( entries 1 - 6 ). the polymer was precipitated with methanol and was collected by filtration and washed with acidified methanol ( 10 % hcl ), methanol and acetone sequentially and dried under high vacuum to constant weight . the activity of the polymerization was calculated from the mass of the product obtained . in reactions utilizing triethylsilane ( et 3 sih ) as the quenching agent ( table 7 , entries 7 & amp ; 8 and table 8 ), 1 ml et 3 sih in 2 ml of toluene was added to the addition funnel following introduction of the initiator stock solution . the addition funnel was pre - pressurized with ethylene at 50 psi above the desired reaction pressure ( p c2h4 ) and the solution injected into the rapidly stirring reaction mixture at the appropriate time point . living polymerization of propene : a 300 ml parr steel autoclave reactor , equipped with an addition funnel , was loaded inside a glovebox with toluene ( 100 ml ) and solid mao so that [ al ]/[ ni ]= 250 ( 145 mg , 2 . 50 mmol ). a stock solution of initiator 1 was prepared and 10 μmol of initiator 1 in approximately 1 ml ch 2 cl 2 was added to the addition funnel . the reactor was sealed inside the glovebox . the reactor was cooled in a dry - ice / acetone bath and 5 ml propene was transferred into the reactor . the reactor was brought to the appropriate reaction temperature ( t rxn ) and the polymerization was initiated via injection of the solution of initiator 1 under argon . the reaction temperature ( t rxn ) was controlled by means of a dry - ice / acetone bath and found to be ± 2 ° c . as monitored by an internal thermocouple . in order to monitor the number average molecular weight ( m n ) and polydispersity ( pdi ) of the product with time ; 5 . 0 ml aliquots of the polymerization solution were taken at 20 , 40 , 60 and 90 minutes under a flow of argon using a gas - tight syringe . the contents of the syringe were immediately quenched with methanol . volatiles were removed in - vacuo and the residue washed with acidified methanol ( 10 % hcl ), methanol and acetone sequentially and dried under high vacuum . the remaining residue was dissolved in approximately s grams of o - dichlorobenzene by heating the contents to 135 ° c . with agitation . gel permeation chromatography ( gpc ) of this solution was used to obtain the m n and pdi of each polymer sample , as shown in table 9 . the reaction at a time of 120 minutes was quenched by loading the addition funnel with methanol ( 5 ml ) and injecting the methanol , under argon , directly into the stirring reaction mixture . the polymer was precipitated with methanol and was collected by filtration and washed with acidified methanol ( 10 % hcl ), methanol and acetone sequentially and dried under high vacuum to constant weight . the activity of the polymerization was calculated from the mass of the product obtained . living polymerization of 1 - hexene : a 300 ml parr steel autoclave reactor , equipped with an addition funnel , was loaded inside a glovebox with toluene ( 125 ml ), 1 - hexene ( 15 ml , 120 . 0 mmol ) and solid mao so that [ al ]/[ ni ]= 250 ( 181 . 3 mg , 3 . 13 mmol ). a stock solution of initiator 1 was prepared and 12 . 5 μmol of initiator 1 in approximately 1 ml ch 2 cl 2 was added to the addition funnel . the reactor was sealed inside the glovebox and cooled in a dry - ice / acetone bath to the appropriate reaction temperature ( t rxn ). the polymerization was initiated via injection of the solution of initiator 1 under argon . the reaction temperature ( t rxn ) was controlled by means of a dry - ice / acetone bath and found to be ± 2 ° c . as monitored by an internal thermocouple . in order to monitor the number average molecular weight ( m n ) and polydispersity ( pdi ) of the product with time ; 5 . 0 ml aliquots of the polymerization solution were taken at 20 , 40 , 60 and 90 minutes under a flow of argon using a gas - tight syringe . the contents of the syringe were immediately quenched with methanol . volatiles were removed in - vacuo and the residue washed with acidified methanol ( 10 % hcl ), methanol and acetone sequentially and dried under high vacuum . the remaining residue was dissolved in approximately 5 grams of o - dichlorobenzene by heating the contents to 135 ° c . with agitation . gel permeation chromatography ( gpc ) of this solution was used to obtain the m n and pdi of each polymer sample as shown in table 10 . the reaction at a time of 120 minutes was quenched by loading the addition funnel with methanol ( 5 ml ) and injecting the methanol , under argon , directly into the stirring reaction mixture . the polymer was precipitated with methanol and the precipitated polymer collected by filtration and washed with acidified methanol ( 10 % hcl ), methanol and acetone sequentially and dried under high vacuum to constant weight . the activity of the polymerization was calculated from the mass of the product obtained . although the present invention has been described in connection with the preferred embodiments , it is to be understood that modifications and variations may be utilized without departing from the principles and scope of the invention , as those skilled in the art will readily understand . accordingly , such modifications may be practiced within the scope of the claims . 1 . b . rieger , l . baugh , s . striegler , s . kacker , late transition metal catlysis , john wiley & amp ; 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