title: Mono N,C,N-pincer complexes of titanium, vanadium and niobium. Synthesis, structure and catalytic activity in olefin polymerisation.
abstract: Transmetallation of 4,4'-bis{(2,6-bis[(dimethylamino)methyl]phenylgold)diphenyl-phosphino}biphenyl (3) with MCl(4) (M = Ti, NbCl, V) in benzene gave the corresponding transition metal pincer complexes (4) and insoluble 4,4'-bis[P-(chloro gold(I))diphenylphosphino]biphenyl (2), which can be quantitatively recovered and recycled. Interestingly, 3 did not react with TiCl(3). However, reaction of 2,6-bis[(dimethylamino)methyl]phenyllithium (1) with TiCl(3) resulted in formation of the novel diaryltitanium(IV) compound 5 (16% yield), comprising one N,C,N-mer bound NCN-pincer ligand and a second NCN-pincer ligand that is rearranged from a 1,2,6-isomer to a 1,2,4 one. The latter NCN-ligand is dianionic and is bidentate bonded; one of the CH(2)NMe(2) substituents (para to C'(ipso)) is non-coordinated, while the second CH(2)NMe(2) group, after C-H activation of one of the Me groups, is η(2)-C,N-bonded to the titanium centre trans to C(ipso) of the mer-NCN ligand. The new NCN-pincer metal complexes 2,6-bis[(dimethylamino)methyl]phenylTiCl(3) (4a) and 2,6-bis[(dimethylamino)methyl]-phenylVCl(2) (4d) gave, after immobilization on MgCl(2)-based supports, very high activity in ethene polymerisation.
authors.affiliation: Debye Institute for Nanomaterials Research, Organic Chemistry and Catalysis, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Chuchuryukin
authors.forename: Rubin
authors.initials: R
authors.lastname: Huang
authors.forename: Ernst E
authors.initials: EE
authors.lastname: van Faassen
authors.forename: Gerard P M
authors.initials: GP
authors.lastname: van Klink
authors.forename: Martin
authors.initials: M
authors.lastname: Lutz
authors.forename: John C
authors.initials: JC
authors.lastname: Chadwick
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Spek
authors.forename: Gerard
authors.initials: G
authors.lastname: van Koten
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D009556:Niobium / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry; D058105:Polymerization; D014025:Titanium / Q000737:chemistry*; D014639:Vanadium / Q000737:chemistry*
chemical_list: D000475:Alkenes; D056831:Coordination Complexes; D008024:Ligands; D010720:Phosphines; D014639:Vanadium; D009556:Niobium; D014025:Titanium; D001554:Benzene