2D-QSPR studies on substituting PNP-Cr catalyst systems for highly selective ethylene oligomerization

doi:10.3969/j.issn.0438-1157.2014.01.017

Abstract

Abstract: 1-Hexene and 1-octene are important comonomers for the synthesis of high performance polyolefins. Recently, Cr-bis(diphenylphosphino)amine (PNP-Cr) catalysts show the potential as excellent candidates for highly selective ethylene trimerization/tetramerization. In this work, a series of substituting PNP-Cr catalysts were studied by two-dimensional quantitative structure-property relationship (QSPR) method based on density functional theory (DFT) calculations. The heuristic method (HM) and best multi-linear regression (BMLR) were used for establishing the best linear regression models to describe the relationship between catalyst selectivity and its structure. Both Cr(Ⅰ) and Cr(Ⅱ) active site models for ethylene trimerization/tetramerization were considered. It was found that using self-defined descriptors from DFT calculations could increase the relativity and stability of the models. Monovalent Cr(Ⅰ) center was the most plausible active site for ethylene trimerization, while ethylene tetramerization was most possibly proceeded over divalent Cr(Ⅱ) active site. The skeleton structures of the PNP-Cr system especially a small PNP angle were crucial for achieving excellent catalytic selectivity. Nine new PNP ligands with high selectivity towards ethylene trimerization/tetramerization were predicted based on the best linear regression models providing a good basis for further development of novel catalyst systems with better performance.

Key words: 2D-QSPR, computational chemistry, ethylene trimerization/tetramerization catalysts, molecular simulation, heuristic method, best multi-linear regression

摘要： 1-己烯和1-辛烯是制备高性能聚烯烃产品的重要共聚单体，近年来，PNP型铬系乙烯选择性三聚/四聚催化体系成为本领域研究热点。针对实验研究报道的系列氮上取代PNP型铬系催化剂，采用二维定量构效关系（QSPR）方法结合密度泛函理论（DFT）建立了该催化体系1-己烯、1-辛烯选择性的线性回归模型。研究中同时采用了启发式方法和最佳多元线性回归方法，考察了自定义描述符和铬金属活性中心价态（包括一价和二价）对线性回归模型的影响。通过分析发现：基于DFT的自定义描述符的引入能够明显提高模型的相关性和稳定性；基于一价Cr的活性中心模型更适合关联乙烯三聚选择性，二价Cr的活性中心模型更适合关联乙烯四聚选择性；PNP-Cr骨架几何结构尤其是较小的PNP角度是获得较高1-己烯和1-辛烯选择性的关键。最后，根据最佳线性回归模型对新型PNP配体进行了预测，发现了9种新的PNP配体结构可能具有更高的1-辛烯或1-己烯/1-辛烯共选择性，为进一步的实验开发奠定了良好的理论基础。

关键词: 二维定量构效关系, 计算化学, 乙烯三聚/四聚催化剂, 分子模拟, 启发式方法, 最佳多元线性回归

CLC Number:

TQ221.21⁺7

TANG Siyang, LIU Zhen, ZHAN Xingwen, CHENG Ruihua, HE Xuelian, LIU Boping. 2D-QSPR studies on substituting PNP-Cr catalyst systems for highly selective ethylene oligomerization[J]. CIESC Journal, 2014, 65(1): 131-142.

唐思扬, 刘振, 占兴稳, 程瑞华, 何雪莲, 刘柏平. 乙烯选择性齐聚取代PNP-Cr催化体系的二维定量构效关系[J]. 化工学报, 2014, 65(1): 131-142.

References 35

[1]	Agape T. Selective ethylene oligomerization: recent advances in chromium catalysis and mechanistic investigations[J]. Coordination Chemistry Reviews, 2011, 255(7/8): 861-923
[2]	van Leeuwen P W N M, Clément N D, Tschan M J L. New processes for the selective production of 1-octene[J]. Coordination Chemistry Reviews, 2011, 255(13/14): 1499-1517
[3]	McGuinness D S. Olefin oligomerization via metallacycles: dimerization, trimerization, tetramerization, and beyond[J].Chemical Reviews, 2011, 111(3): 2321-2341
[4]	Blann K, Bollmann A, Dixon J T, Hess F M, Killian E, Maumela H, Morgan D H, Neveling A, Otto S, Overett M J. Highly selective chromium-based ethylene trimerization catalysts with bulky diphosphinoamine ligands[J]. Chemical Communications, 2005(5):620-621
[5]	Elowe P R, McCann C, Pringle P G, Spitzmesser S K, Bercaw J E. Nitrogen-linked diphosphine ligands with ethers attached to nitrogen for chromium-catalyzed ethylene tri-and tetramerizations[J]. Organometallics, 2006, 25(22): 5255-5260
[6]	McGuinness D S, Wasserscheid P, Keim W, Hu C, Englert U, Dixon J T, Grove C. Novel Cr-PNP complexes as catalysts for the trimerisation of ethylene[J]. Chemical Communications, 2003, 689(23): 334-335
[7]	McGuinness D S, Wasserscheid P, Morgan D H, Dixon J T. Ethylene trimerization with mixed-donor ligand (N, P, S) chromium complexes: effect of ligand structure on activity and selectivity[J]. Organometallics, 2005, 24(4): 552-556
[8]	Bollmann A, Blann K, Dixon J T, Hess F M, Killian E, Maumela H, McGuinness D S, Morgan D H, Neveling A, Otto S, Overett M, Slawin A M Z, Wasserscheid P, Kuhlmann S. Ethylene tetramerization: a new route to produce 1-octene in exceptionally high selectivities[J]. J. Am. Chem. Soc., 2004, 126(45): 14712-14713
[9]	Overett M J, Blann K, Bollmann A, Dixon J T, Haasbroek D, Killian E, Maumela H, McGuinness D S, Morgan D H. Mechanistic investigations of the ethylene tetramerisation reaction[J]. J. Am. Chem. Soc., 2005, 127(30): 10723-10730
[10]	Kuhlmann S, Blann K, Bollmann A, Dixon J T, Killian E, Maumela M C, Maumela H, Morgan D H, Pretorius M, Taccardi N, Wasserscheid P. N-substituted diphosphinoamines: toward rational ligand design for the efficient tetramerization of ethylene[J]. Journal of Catalysis, 2007, 245(2): 279-284
[11]	Killian E, Blann K, Bollmann A, Dixon J T, Kuhlmann S, Maumela M C, Maumela H, Morgan D H, Nongodlwana P, Overett M J, Pretorius M, Hoefener K, Wasserscheid P. The use of bis(diphenylphosphino)amines with N-aryl functionalities in selective ethylene tri-and tetramerisation[J]. Journal of Molecular Catalysis A: Chemical, 2007, 270(1/2): 214-218
[12]	Blann K, Bollmann A, de Bod H, Dixon J T, Killian E, Nongodlwana P, Maumela M C, Maumela H, McConnell A E, Morgan D H, Overett M J, Pretorius M, Kuhlmann S, Wasserscheid P. Ethylene tetramerisation: subtle effects exhibited by N-substituted diphosphinoamine ligands[J]. Journal of Catalysis, 2007, 249(2): 244-249
[13]	Carter A, Cohen S A, Cooley N A, Murphy A, Scutt J, Wass D F. High activity ethylene trimerization catalysts based on diphosphine ligands[J]. Chemical Communications, 2002(8): 858-859
[14]	Cloete N, Visser H G, Engelbrecht l, Overett M J, Gabrielli W F, Roodt A. Ethylene tri-and tetramerization: a steric parameter selectivity switch from X-ray crystallography and computational analysis[J]. Inorganic Chemistry, 2013, 52(5):2268-2270
[15]	Jiang T, Zhang S, Jiang X L, Yang C, Niu B, Ning Y N. The effect of N-aryl bisphosphineamine ligands on the selective ethylene tetramerization[J]. Journal of Molecular Catalysis A: Chemical, 2008, 279(1): 90-93
[16]	Liu Qingyun(刘清云), Gao Rong(高榕), Hou Junxian(侯俊先), Sun Wenhua(孙文华). Tridentate P—N—P chromium complexes: synthesis, characterization and their ethylene oligomerization and polymerization[J]. Chinese Journal of Organic Chemistry(有机化学), 2013, 33(4): 808-814
[17]	Jiang T, Chen H, Ning Y N, Chen W. Preparation of 1-octene by ethylene tetramerization with high selectivity[J]. Chinese Science Bulletin, 2006, 51(5): 521-523
[18]	Jiang T, Tao Y Q, Gao X L, Mao G L, Chen H X, Ning Y N. Ethylene tetramerization with a highly active and long-lifetime trinuclear diphenylphosphinoamine/Cr(Ⅲ)/MAO catalyst[J]. Chinese Science Bulletin, 2012, 57(13): 1510-1515
[19]	Briggs J R. The selective trimerization of ethylene to 1-hexene[J]. J. Chem. Soc. Chem. Comm., 1989, 11: 674-675
[20]	Manyik R M, Walker W E, Wilson T P A. Soluble chromium-based catalyst for ethylene trimerization and polymerization[J]. Journal of Catalysis, 1977, 47(2): 197-209
[21]	Agapie T, Labinger J A, Bercaw J E. Mechanistic studies of olefin and alkyne trimerization with chromium catalysts: deuterium labeling and studies of regiochemistry using a model chromacyclopentane complex[J]. Journal of the American Chemical Society, 2007, 129(46): 14281-14259
[22]	McGuinness D S. Oligomerization of alpha-olefins via chromium metallacycles[J]. Organometallics, 2009, 28(1): 244-248
[23]	Dixon J T, Green M J, Hess F M, Morgan D H. Advances in selective ethylene trimerization — a critical overview[J]. J. Organomet. Chem., 2004, 689(23): 3641-3668
[24]	Vidyaratne I, Nikiforov G B, Gorelsky S I, Gambarotta S, Duchateau R, Korobkov I. Isolation of a self-activating ethylene trimerization catalyst[J]. Angewandte Chemie International Edition, 2009, 48(35): 6552-6556
[25]	Jabri A, Mason C B, Gambarotta S, Burchell T J, Duchateau R. Isolation of single-component trimerization and polymerization chromium catalysts: the role of the metal oxidation state[J]. Angewandte Chemie, International Edition, 2008, 47(50): 9717-9721
[26]	Qi Y, Dong Q, Zhong L, Liu Z, Qiu P Y, Cheng R H, He X L, Vanderbilt J, Liu B P. Role of 1, 2-dimethoxyethane in the transformation from ethylene polymerization to trimerization using chromium tris(2-ethylhexanoate)-based catalyst system: a DFT study[J]. Organometallics, 2010, 29(7):1588-1602
[27]	Yang Y, Liu Z, Zhong L, Qiu P Y, Dong Q, Cheng R H, Vanderbilt J, Liu B P. Spin surface crossing between chromium(Ⅰ)/sextet and chromium(Ⅲ)/quartet without deprotonation in SNS-Cr mediated ethylene trimerization[J]. Organometallics, 2011, 30(19): 5297-5302
[28]	Klemps C, Payet E, Magna L, Saussine L, Le Goff X F, Le Floch P. PCNCP ligands in the chromium-catalyzed oligomerization of ethylene: tri-versus tetramerization[J]. Chemistry-a European Journal, 2009, 15(33): 8259-8268
[29]	Budzelaar P H M. Selective ethylene oligomerization: recent advances in chromium catalysis and mechanistic investigations[J]. Canadian Journal of Chemistry, 2009, 87(7): 832-837
[30]	Rabeah J, Bauer M, Baumann W, McConnell A E C, Gabrielli W F, Webb P B, Selent D, Brückner A. Formation, operation and deactivation of Cr catalysts in ethylene tetramerization directly assessed by operando EPR and XAS[J]. ACS Catalysis, 2013, 3(1): 95-102
[31]	Brückner A, Jabor J K, McConnell A E C, Webb P B. Monitoring structure and valence state of chromium sites during catalyst formation and ethylene oligomerization by in situ EPR spectroscopy[J]. Organometallics, 2008, 27(15): 3849-3856
[32]	Becke A D. Density-functional thermochemistry(Ⅲ): The role of exact exchange[J]. J. Chem. Phys., 1993, 98(7): 5648-5652
[33]	Lee C, Yang W, Parr R G. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density[J]. Phys. Rev. B, 1988, 37(2): 785-789
[34]	Harvey J N, Aschi M, Schwarz H, Koch W. The singlet and triplet states of phenyl cation. A hybrid approach for locating minimum energy crossing points between non-interacting potential energy surfaces[J]. Theoretical Chemistry Accounts, 1998, 99(2): 95-99
[35]	Martí R, Reinelt G. The Linear Ordering Problem, Exact and Heuristic Methods in Combinatorial Optimization[M] New York: Springer Heidelberg Dordrecht, 2011: 17-82