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

Abstract

The new neutral nickel complexes PhC(NSiMe 3 ) 2 Ni(acac) (3), PhC(NSiMe 3 ) 2 Ni(acac)-(TMEDA) (4), [PhC(NSiMe 3 ) 2 ] 2 Ni 2 (5), [PhC(NSiMe 3 ) 2 ] 2 Ni‚Li 2 Br 2 (TMEDA) 2 ( 6), (TMEDA) 2 Ni (7), p-MePhC(NSiMe 3 ) 2 Ni(acac) (8), p-MePhC(NSiMe 3 ) 2 Ni(acac)(TMEDA) (9), [p-MePhC-(NSiMe 3 ) 2 ] 2 Ni (10), NiMe 2 Py 2 (11) and [p-MePhC(NSiMe 3 )] 2 Ni(Py) ( 14) have been synthesized and characterized. The solid-state molecular structures of all complexes have been confirmed by low-temperature X-ray diffraction analysis. The methyl complex p-MePhC(NSiMe 3 ) 2 Ni-(Me)(Py) ( 13) is not stable and rapidly decomposes, forming the complex [p-MePhC(NSiMe 3 )] 2 -Ni(Py) ( 14). Complex 3 activated with MAO has been shown to be an efficient catalytic system for the norbornene vinyl-type polymerization. The activity of the catalyst and the molecular weights of the resulting polynorbornenes were found to be dependent on the reaction time, the MAO/precatalyst ratio, and the reaction temperature. In addition, this catalytic system has been found to dimerize propylene to a mixture of hexenes with a high turnover frequency of η ) 9040 h -1 and oligomerize ethylene to either a mixture of C 4 -C 6 or/and C 4 -C 14 products, depending on the temperature and the solvent, extremely rapidly (η ) 83 500 h -1 ).

Metal catalysts for the vinyl/addition polymerization of norbornene

“…Precatalyst Ni-1 could be activated with MAO to show moderate activities around 10 5 g PNB /mol Pd h depending on the reaction conditions [130]. Two different catalyst activation processes were tested.…”

“…In the first procedure, the precatalyst and MAO were mixed, generating the active species before the addition of norbornene. In the second procedure the active sites were generated by the activation of complex Ni-1 in the presence of the monomer with the first procedure giving higher activities [130]. Furthermore, it was shown that the activities increased with a rising Al/Ni ratio up to 500 and then decreased again.…”

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

“…In recent years there has been increasing interest in the development of late transition metal catalysts for olefin polymerization [1][2][3][4][5][6] due to their application in preparation of high molecular weight polyethylene (PE) and toleration of polar solvents, even polar monomers [7][8][9][10][11].…”

Strained Diphosphines Built upon a Calix[4]arene Skeleton. Synthesis of a Highly Active Norbornene Polymerization Catalyst

“…Zirconocene and titanocene complexes have proven to be efficient for the vinyl polymerization of norbornene. [11][12][13][14][15][16] Many late transition metal catalysts based on cobalt, [17,18] nickel, [19][20][21][22][23][24][25][26][27] or palladium [28][29][30][31][32][33] have also been used successfully.…”