Ligand effects in chromium diphosphine catalysed olefin co-trimerisation and diene trimerisation.
Dalton Trans
; (2): 560-7, 2010 Jan 14.
Article
en En
| MEDLINE
| ID: mdl-20023994
A series of symmetric and unsymmetric N,N-bis(diarylphosphino)amine ('PNP') ligands (Ar2PN(R)PNAr'2: R = Me, Ar2 = o-anisyl, Ar'2 = Ph, 1, R = Me, Ar2 = o-tolyl, Ar'2 = Ph, 2, R = Me, Ar2 = Ph(o-ethyl), Ar'2 = Ph, 3, R = Me, Ar2 = Ar'2 = o-anisyl, 4, R = iPr, Ar2 = Ar'2 = Ph, 5) and symmetric N,N'-bis(diarylphosphino)dimethylhydrazine ('PNNP') ligands (Ar2PN(Me)N(Me)PAr2: Ar2 = o-tolyl, 6, Ar2 = o-anisyl, 7) have been synthesised. Catalytic screening for ethene/styrene co-trimerisation and isoprene trimerisation was performed via the in situ complexation to [CrCl3(THF)3] followed by activation with methylaluminoxane (MAO). PNNP catalytic systems showed a significant increase in activity and selectivity over previously reported PNP systems in isoprene trimerisation. Comparing the symmetric and unsymmetric variants in ethene and styrene co-trimerisation resulted in a switch in selectivity, an unsymmetric catalytic (o-anisyl)2PN(Me)PPh2 (1) ligand system affording unique incorporation of two styrenic monomers into the co-trimer product distribution differing from the familiar two ethene and one styrene -substituted alkenes. Complexes of the type [(diphosphine)Cr(CO)4] 8-11 were also synthesised, the single-crystal X-ray diffraction of which are reported. We propose the mechanisms of these catalytic transformations and an insight into the effect of the ligand series on the chromacyclic catalytic intermediates.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Dalton Trans
Asunto de la revista:
QUIMICA
Año:
2010
Tipo del documento:
Article
Pais de publicación:
Reino Unido