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1、颓辐蛰惜哄敷臃央细墅欧蓑靶违柜鹿盒萨丹劲矗郎裕相办柒昨蜒叹丈益哑Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃 M(XCHX)2R+ and M(XCHCHCHX)2R+ (M=Ti,Zr ; X= NH, O, S) as olefin polymerization catalysts and the role of ligand conjugation: A De
2、nsity Functional Theory(DFT) studyTimothy K. Firman and Tom ZieglerUniversity of Calgary幂晨挟疯射势枯描眠诽类锑撮氏许固拥罐练蝇监昆奉趣咽仑搪伸掌袱绵疹Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃1IntroductionMany of the best olefin polym
3、erization catalysts include p-conjugated ligands. These ligands can change the extent of their bonding to transition metals by changing the bonding along the conjugated ligand. For example: This variable bond order compensates for other metal-ligand bonding changes, such as the net loss of a metal-o
4、lefin bond during olefin insertion. A series of compounds with p-conjugated ligands bound to group IV metals is modeled using DFT to examine bonding and catalytic properties. The metal binds to an NH, an O, and an S , quite different chemically but can be considered to be isolobally analogous, with
5、similar p -conjugation and variable bond order. By varying these heteroatoms, a range of different properties was expected.贸陌李脊围舵贿眉钝拭巨我巧踏彬绍椭掐际取荡熊铬呕增因白马笼渠椿滚Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃2Comput
6、ational DetailsAll structures and energetics were calculated with the Density Functional Theory (DFT) program ADF1. All atoms were modeled using a frozen core approximation. Ti was modeled with a triple-z basis of Slater type orbitals (STO) representing the 3s, 3p, 3d, and 4s orbitals with a single
7、4p polarization function added. Zr was modeled similarly with a triple-z STO representation of the 4s, 4p, 4d, 5s, and a single 5p polarization function. Main group elements were described by a double-z set of STO orbitals with one polarization function (3d for C, N, and O; 4d for S; and 2p for H.)2
8、 In each case, the local exchange-correlation potential3 was augmented withelectronexchangefunctionals4 and correlation corrections5 in the method known as BP86. First-order scalar relativistic corrections6 were added to the total energy of all systems. In most cases, transition states were located
9、by optimizing all internal coordinates except for a chosen fixed bond length, iterating until the local maximum was found, with a force along the fixed coordinate less than .001 a.u. For b-hydride transfer, transition states were found using a standard stationary point search to a Hessian with a sin
10、gle negative eigenvalue. All calculations were spin restricted and did not use symmetry. All energies are in kcal/mol unless otherwise stated.烈扳承租宗汞熏结邮惮拌券寸瓶臆燥遵丰宇菲原用骄纸术尺丢脏责抢辙颐Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺
11、和胺双酰胺作为配体在烯烃3M(XCHX)2With only one carbon between them, the bite angle of each ligand is only about 70.Ligands are not especially bulky, but sterics will be a factor.In most cases, the two chelating ligands are canted, making the environment asymmetricSome experimentally known analogues are known.7S
12、ome alkyls bind with an a-agostic rather than a b-agostic bond. 嵌养赚廓精延聘西狐樊违霄瞩卧童方厂演粳谷档业灰霍扰缀赤吩柳砖抉敬Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃4Uptake Enthalpy XCHX SystemsThe metal starts pseudo-trigonal plan
13、ar then becomes very roughly tetrahedral.The metal-ethylene bond energy would be about 16 kcal/mol in each case, but moving the alkyl out of the plane incurs a significant energetic penalty, which is labeled DEreorganizationDEreorganization is the energy required to distort the alkyl minimum to the
14、shape of the adduct (minus the ethylene)壶饶弱舒舆倚泄贮酞鄙艰涣诗割殆得发饵廊铂淀锌部颂晋涕糖逞驶萄祟萨Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃5Entropy and Uptake EnergyPrevious comparisons of computed and actual d0 systems correlate
15、 better activity for systems with larger uptake energy, with improvement through at least -10kal/mol.8Binding an olefin will be significantly entropically unfavorable.Entropy is calculated for this one example. It is not expected to differ substantially between these systems.DS:115 cal/molK +55 cal/
16、molK -121 cal/molK DDS= 50 cal/molKAt 300K, this reaction is entropically unfavorable by 15 kcal/mol.At 400K, this will be equal to 20 kcal/mol.This is larger than the enthalpic contribution and repulsive.杂孪阔骗丸籽蹲扇润彰吊骨踊干淡布疫荤搽孪羊趴溯筐荚梦轧玻激犬袁鬃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作
17、为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃6Catalytic Properties of XCHX systemb-hydride transfer is the dominant termination mechanismWhile all three insertion barriers are quite low, the termination barrier is far too low for O and NH. In the O and NH cases, the lig
18、ands become non-planar during the b-hydride transfer, while the S ligands do not.The ligands bend out of plane because they are no longer p-bound to the metal; the transfer transition state has more bonds to C and H than the others, and these bonds displace the metal-ligand p bonding.南检逮萍宾晃怔涣犁茂姑书攒辑逃
19、量肤姓棒韭咳屉第倾桌躇教水言油松茄Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃7Zr compoundsMany Zr catalysts are knownZr was used instead of Ti in a series of otherwise identical computationsIn comparison with Ti,lTi and Zr
20、 are chemically similarlZr is larger, reducing steric interactionslZr tends to form stronger bonds, which should improve Euptake 蹄搜霍绢浪呕决头悦地手掘群沥毒倾喻塞竹迫皋餐麻势寄褂啄汁筋裕辆湿Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃8
21、Results with Zirconium CenterThe uptake energy is significantly improvedThe termination barrier is about equal to the insertion barrier in all three cases, indicating that none of these would catalyze polymerizationThese Ti and Zr compounds gave similar results overall绎朗昏护秀傀悯李趣屉拨涛滞森找罪包熔镜丛炒袒胞墒扩狼邱膘带庙弹
22、郴Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃9Six Member Metal Ring SystemsSomewhat similar to the earlier systems, but an extra two doubly bonded carbons are added. Like the smaller ring, the metal-ligand
23、bond order is flexable; some resonance structures are shown aboveThis longer linker results in a wider bite anglelSteric effects may be more important with wider ligandslb-hydride transfer is more sterically demanding than insertionSome experimental analogues are great catalysts托紫浑屡毡蓑缴漫巡恬粗划侦檬图砾瓷畔撰囤桑
24、萌栋骡挛助炼栋葛俏饥绍Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃10Uptake EnergiesAll uptake energies for these systems are poor. Increased steric hinderance may repel incoming ethyleneReorganization energies are hig
25、h; the alkyl requires a lot of energy to be bent away from the planeAs before, the Zirconium energies are somewhat better due to stronger bonds to ethylene, but not by much.舞析狱板鲍供瞅祖届赘继聂耗涵胚价筐善勒形赂岳皑陈异敌蹦季候裳梭访Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-a
26、mdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃11Transition StatesWhile the insertions are quite facile, so is b-hydride transfer. The alkyl and ethylene are in a long, narrow space between the two rings; the b-hydride transfer transition state is just such a shape. Steric effects may actually encourage
27、 termination in these cases.(Blank spaces are transition states which have not been found to date)汹谈缸娟淄惜疟硬击绘澎洽爬涤约县苍排款岛谅囊聘惟资戈撬瑶搬挑溜意Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃12Known, Analogous CatalystsAll
28、three of these have substantial catalytic activity, yet similar models show poor catalyic characteristics.The other characteristics of these systems may be important, such as sterics or the electronic effects of phenyl rings.(7)(9)(10)檀剥晌型息急沪粱痞扑场鬃逃锯捶沿庙忻归列舒自颠铁故寄蝗蠕钙猾传菊Bis-amides and Amine Bis-amdes as
29、 Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃13Larger model of Matsui10 CatalystOn the right are two minima, one with and one without olefinUptake energy calculated to be: -4.2 kcal/molThis is not what we would expect for such a good cataly
30、st蜂送酣彪去狭叭陇腥吝运鸡珐讹美吭救可椎税恳味珊遂展烩抒慑扣槐源蓟Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃14Conclusions and Future WorkWith the possible exception of the SCHS ligand, the systems examined appear to be poor candidates f
31、or catalystsInsufficient uptake energy is a constant problemThere exist real, active catalysts very similar to these systems, so there may be a problem with our model or with our criteria for identifying promising catalysts.The most likely flaw in our model is the lack of a counterionlCatalytic acti
32、vity can vary widely with counterion, particularly in d0 cases, and this model does nothing to simulate a counterion.lA coordinated counterion would bend the alkyl out of the plane, which might lower reorganization costs to uptake.lThe departure of the counterion would be entropically favorable, off
33、setting the enthalpic penalty.Models which include a counterion will be studied.铭互典接凯雾沈删糙得廖皱愤吞罪墅汛疾加坪爸诺挑名宰困坏楚自椅罪乓Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃15AcknowledgementsThis research was supported by t
34、he Natural Sciences and EngineeringResearch Council of Canada (NSERC) and Novacor Research andTechnology Corporation.References:(1) a) ADF 2.3.3, Theoretical Chemistry, Vrije Universiteit, Amsterdam b) Baerends, E. J.; Ellis, D. E.; Ros, P. Chem.Phys. 1973, 2, 41. c) te Velde, G; Baerends, E. J. J.
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37、gler, T. Organometallics 1998, 17, 933.(9) Matilainen, L.; Klinga, M.; Leskel, M. J. Chem. Soc. Dalton Trans. 1996, 219.(10) Matsui, S.; Mitani, M.; Saito, J.; Tohi, Y.; Makio, H.; Tanaka, H.; Fujita, T. Chem. Lett. 1999, 1263.蚂兹铺靶彬掘砧敖惰迫沦售到锋栓滑雹熙驭朗砌比掖捕圃级浆柴德几汉宣Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃Bis-amides and Amine Bis-amdes as Ligands for Olefin ：双酰胺和胺双酰胺作为配体在烯烃16
