Ethylene polymerization using an asymmetric dinuclear titanocene catalyst carrying a novel 3-oxa-pentamethylene bridge

The asymmetric 3-oxa-pentamethylene bridged dinuclear titanocenium complex (CpTiCl2)2 (η5-C9H6(CH2CH2 OCH2CH2)-η5-C5H3 CH3) (1) has been prepared, characterized by 1H NMR spectroscopy and elemental analysis, and after activation with MAO tested as a homogenous catalyst for the polymerization of ethylene. The results show that the catalytic activity of 1 as well as the molecular weight of the produced polyethylene are higher than those using the alkylidene bridged asymmetric dinuclear metallocenes (CpTiCl2)2 (η5-C9H6(CH2) n-η5-C5H4), n = 3 (4), 4 (5). The molecular weight distribution of polyethylene produced with 1/MAO reaches 11.00 and the HT-GPC curve shows a bimodal distribution. The melting point of the polyethylene obtained by 1/MAO is higher than 135 °C and the 13C NMR spectrum of PE shows only one strong signal at 30 ppm for the methylene units indicating a highly linear and crystalline polymer.