750587-05-4Relevant academic research and scientific papers
New bulky bis(amino)cyclodiphosph(III)azanes and their titanium(IV) complexes: Synthesis, structures and ethene polymerization studies
Axenov, Kirill V.,Kotov, Vasily V.,Klinga, Martti,Leskelae, Markku,Repo, Timo
, p. 695 - 706 (2004)
Bis(amino)cyclodiphosph(III) azanes cis-[(RNH)(PN-tBu)]2, R = 2,6-iPr2C6H3 (2), 2-tBuC6H 4 (3), 2-CF3C6H4 (4), 2,5-tBu 2C6H3 (5), Ph2CH (6), 2,4-Me 2C6H3 (7), 2,6-Et2C 6H3 (8), have been synthesized in the presence of Et 3N by a nucleophilic substitution reaction of cis-(ClPN-tBu) 2 (1) with the corresponding bulky aryl and alkylamines. The bis(amino)-cyclodiphosph(III)azanes 2-8 adopt the thermodynamically stable cis-configuration - a prerequisite for efficient metal complex formation. Deprotonation of bis(amino)cyclodiphosph(III)azanes with nBuLi slowly afforded the corresponding salts, cis-[(2,4-Me2C6H 3N)(PN-tBu)]2Li2(THF)2. The crystal structure of cis-[(2,4-Me2C6H3N)(PN-tBu)] 2Li2(THF)2 (9) consists of a heterocube of two lithium atoms, two nitrogen atoms and a cyclodiphosph(III)azane ring. Transmetallation of Li compounds by TiCl4 was unselective and led to a complex mixture of products. The direct reaction of cis-bis (amino)cyclodiphosph(III)azanes with Ti(NMe2)4 is the most efficient method to prepare the corresponding titanium(IV) bis-amido complexes cis-[(RN)(PNtBu)]2Ti(NMe2)2 (11a, 12a, 14a, 15a). In the solid state, cis-[(PhN)(PN-tBu)]2Ti(NMe 2)2 (11a) adopts a highly distorted trigonal-bipyramidal configuration at the metal center. These bis-amido titanium(IV) complexes have been subsequently transformed into the dichlorides cis-[(RN)(PN-tBu)] 2TiCl2 (12-15) with Me3SiCl. After MAO activation the complexes possess moderate catalytic activity in ethene polymerization and produce linear polyethylene with molar masses of up to 2.6 × 106 g/mol and with narrow polydispersities. The catalytic activity and polymer properties depend strongly on the bulkiness of the ligand substituents; cis-[(2,6-iPr2C6H3N)(PN-tBu)] 2TiCl2 (14) gave the highest activity (231 kg PE/mol cat × bar × h). ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).
