Polymerization of methyl methacrylate catalyzed by mono-/bis-salicylaldiminato nickel(II) complexes and methylaluminoxane

Abstract

Two types of salicylaldiminato-based nickel complexes, mono-ligated Ni(II) complexes ([O-C₆H₄-o- C(H)=N-Ar]Ni(PPh₃)(Ph) (5), [O-(3,5-Br₂)C₆H₂-o-C(H)=N-Ar]Ni(PPh₃)(Ph) (6), [O-(3-t-Bu)C₆H₃-o-C(H)=N-Ar]Ni(PPh₃)(Ph) (7)) and bis-ligated Ni(II) complexes ([O-(3,5-Br₂)C₆H₂-o-C(H)=N-Ar]₂Ni (8), [O-(3,5-Br₂)C₆H₂-o-C(H)=N-2-C₆H₄(PhO)]₂Ni (9), Ar=2,6-C₆H₃(i-Pr)₂) were synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), mass spectrography (MS) and elemental analysis (EA). In the presence of methylaluminoxane (MAO) as cocatalyst, all the nickel complexes exhibited high activities for the polymerization of methyl methacrylate (MMA) and syndiotactic-rich poly(methyl methacrylate) (PMMA) was obtained. The complexes with less bulky substituents on salicylaldiminato framework possessed higher activities, while with the same salicylaldiminato, the mono-ligated nickel complexes showed higher catalytic activity than bis-ligated ones.

Key words： late transition metal catalyst; methyl methacrylate; polymerization; salicylaldiminato nickel complexes; methylaluminoxane; syndiotactic structure

Acknowledgments

The project was sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry of China, the Science and Technology Innovation Program of the China National Petroleum Corporation, and the Key Laboratory of Advanced Polymer Materials of Shanghai (Grant No. 08DZ2230500), the Science and Technology Innovation Program of China National Petroleum Corporation.

References

1 Boffa L S, Novak B M. Copolymerization of polar monomers with olefins using transition-metal complexes. Chemical Reviews, 2000, 100(4): 1479–1494

PMID

2 Ittel S D, Johnson L K, Brookhart M. Late-metal catalysts for ethylene homo- and copolymerization. Chemical Reviews, 2000, 100(4): 1169–1204

PMID

3 Mecking S. Olefin polymerization by late transition metal complexes—a root of Ziegler catalysts gains new ground. Angewandte Chemie (International ed. in English), 2001, 40(3): 534–540

PMID

4 Gibson V C, Spitzmesser S K. Advances in non-metallocene olefin polymerization catalysis. Chemical Reviews, 2003, 103(1): 283–315

PMID

5 Rieger B, Baugh L S, Kacker S, Striegler S. Late Transition Metal Polymerization Catalysis. Weinheim: Wiley-VCH, 2003

6 Nelkenbaum E, Kapon M, Eisen M S. Synthesis and molecular structures of neutral nickel complexes catalytic activity of (benzamidinato)(acetylacetonato)nickel for the addition polymerization of norbornene, the oligomerization of ethylene, and the dimerization of propylene. Organometallics, 2005, 24(11): 2645–2659

7 Johnson L K, Killian C M, Brookhart M. New Pd(I1)- and Ni(I1)-based catalysts for polymerization of ethylene and a-olefins. Journal of the American Chemical Society, 1995, 117(23): 6414–6415

8 Mecking S, Johnson L K, Wang L, Brookhart M. Mechanistic studies of the palladium-catalyzed copolymerization of ethylene and r-olefins with methyl acrylate. Journal of the American Chemical Society, 1998, 120(5): 888–899

9 Liu W, Malinoski J M, Brookhart M. Ethylene polymerization and ethylene/methyl 10-undecenoate copolymerization using nickel(II) and palladium(II) complexes derived from a bulky P,O chelating ligand. Organometallics, 2002, 21(14): 2836–2838

10 Sun J, Shan Y, Xu Y, Cui Y, Schumann H, Hummert M. Novel cyclohexyl-substituted salicylaldiminato-nickel(II) complex as a catalyst for ethylene homopolymerization and copolymerization. Journal of Polymer Science. Part A, Polymer Chemistry, 2004, 42(23): 6071–6080

11 Li X F, Li Y G, Li Y S, Chen Y X, Hu N H. Copolymerization of ethylene with methyl methacrylate with neutral nickel(II) complexes bearing β-Ketoiminato chelate ligands. Organometallics, 2005, 24(10): 2502–2510

12 Wang C, Friedrich S, Younkin T R, Li R T, Grubbs R H, Bansleben D A, Day M W. Neutral nickel(II)-based catalysts for ethylene polymerization. Organometallics, 1998, 17(15): 3149–3151

13 Younkin T R, Connor E F, Henderson J I, Friedrich S K, Grubbs R H, Bansleben D A. Neutral, single-component nickel (II) polyolefin catalysts that tolerate heteroatoms. Science, 2000, 287(5452): 460–462

PMID

14 Cui Y, Sun J, Wang L, Shan Y. Bulk polymerization of methyl methacrylate with dinuclear neutral nickel(II)catalyst. J Zhejiang University, 2006, 33: 80–84 (Science Edt)

15 Carlini C, Martinelli M, Raspolli G A M, Sbrana G. Copolymerization of ethylene with methyl methacrylate by Ziegler-Natta-type catalysts based on nickel salicylaldiminate/methylalumoxane systems. Macromolecular Chemistry and Physics, 2002, 203(10-11): 1606–1613

16 Carlini C, Martinelli M, Passaglia E, Raspolli G A M, Sbrana G. Homopolymerization of methyl methacrylate by novel Ziegler-Natta-type catalysts based on bis(chelate)-nickel(II) complexes and methylaluminoxane. Macromolecular Rapid Communications, 2001, 22(9): 664–668

17 Carlini C, Martinelli M, Raspolli G A M, Sbrana G. Highly active methyl methacrylate polymerization catalysts obtained from bis(3,5-dinitro-salicylaldiminate)nickel(II) complexes and methylaluminoxane. Journal of Polymer Science. Part A, Polymer Chemistry, 2003, 41(13): 2117–2124

18 Carlini C, Macinai A, Masi F, Raspolli G A M, Santi R, Sbrana G, Sommazzi A. Ethylene polymerization by bis(salicylaldiminate)nickel(II)/aluminoxane catalysts. Journal of Polymer Science. Part A, Polymer Chemistry, 2004, 42(10): 2534–2542

19 Casiraghi G, Casnati G, Puglia G, Sartori G, Terenghi G. Selective reactions between phenols and formaldehyde: a novel route to salicylaldehydes. J Chem Soc Perkin Trans, 1980, 1: 1862–1865

20 Hidai M, Kashiwagi T, Ikeuchi T, Uchida Y. Oxidative additions to nickel(0): preparation and properties of a new series of arylnickel(II) complexes. Journal of Organometallic Chemistry, 1971, 30(2): 279–282

21 Holm R H. Studies on nickel(II) complexes II. On the solution magnetism of bis-(N-methylsalicylaldimine)-nickel(II) and related complexes. Journal of the American Chemical Society, 1961, 83(23): 4683–4690

22 Hu T, Tang L M, Li X F, Li Y S, Hu N H. Synthesis and ethylene polymerization activity of a novel, highly active single-component binuclear neutral nickel(II) catalyst. Organometallics, 2005, 24(11): 2628–2632