958889-53-7Relevant academic research and scientific papers
Mono- and dinuclear cobalt complexes with chelating or bridging bidentate P,N phosphino- and phosphinito-oxazoline ligands: Synthesis, structures and catalytic ethylene oligomerisation
Jie, Suyun,Agostinho, Magno,Kermagoret, Anthony,Cazin, Catherine S. J.,Braunstein, Pierre
, p. 4472 - 4482 (2007)
Cobalt(ii) complexes of the type [CoCl2(P,N)], where P,N represents a heterobidentate phosphino- or phosphinito-oxazoline-type ligand, have been synthesised and characterised by infrared spectroscopy and elemental analysis. Their molecular structures were established by single-crystal X-ray diffraction in the solid state. Whereas the phosphino-oxazoline complex [CoCl2{Ph2PCH2oxMe2}] (Ph 2PCH2oxMe2 = 2-[(diphenylphosphanyl)-methyl]-4, 4-dimethyl-4,5-dihydro-oxazole) (8) and the phosphinito-oxazoline complexes [CoCl2{Ph2POCH2oxMe2}] (Ph 2POCH2oxMe2 = 1-[4,4-dimethyl-2{1- oxy(diphenylphosphino)-1-methyl}]-4,5-dihydro-oxazole) (9) and [CoCl 2{Ph2POCMe2oxMe2}] (Ph 2POCMe2oxMe2 = 1-[4,4-dimethyl-2- [1-oxy(diphenylphosphino)-1-methylethyl]]-4,5-dihydrooxazole) (10) are mononuclear, the phosphino-oxazoline complexes [CoCl2{μ-i-Pr 2PCH2ox}]2 (i-Pr2PCH2ox = 2-[(diisopropyl-phosphanyl)-methyl]-4,5-dihydro-oxazole) (6) and [CoCl 2{-Ph2PCH2ox}]2 (Ph 2PCH2ox = 2-[(diphenyl-phosphanyl)-methyl]-4,5-dihydro- oxazole) (7) are dinuclear compounds and contain two bridging phosphino-oxazoline ligands which form a 10-membered ring. In the course of this work, the zwitterionic complex [CoCl3{Ph2PCH 2C(O)OCH2CMe2NH3] (11) was obtained and characterised by X-ray diffraction in which the oxazoline ring has been opened. Air-oxidation of the phosphine function of the mononuclear P,N chelate complex 8 yielded the blue N,O-bridged, centrosymmetric dinuclear complex [CoCl2{μ-OPPh2CH2CNCMe2CH 2O}]2 (12) which contains a 12-membered ring. All these complexes are paramagnetic and their magnetic moments in solution were measured by the Evans method. Complexes 6-10 were evaluated in the catalytic oligomerisation of ethylene with AlEtCl2 or methylaluminoxane (MAO) as cocatalysts and provided moderate activities. In the presence of AlEtCl 2 (6-14 equiv.), the selectivities for ethylene dimers were higher than 92% and complex 8 showed the highest turnover frequency with 14 equiv. of AlEtCl2. When MAO was used as cocatalyst, the catalytic activities were similar to those with AlEtCl2 but significant amounts of C 6-C12 oligomers were produced. The Royal Society of Chemistry.
