Aluminum Complexes of Fluorinated Dialkoxy-Diimino Salen-like Ligands: Syntheses, Structures, and Use in Ring-Opening Polymerization of Cyclic Esters

作者：Bouyahyi Miloud; Grunova Ekaterina; Marquet Nicolas; Kirillov Evgueni; Thomas Christophe M; Roisnel Thierry; Carpentier Jean Francois^*

来源：Organometallics, 2008, 27(22): 5815-5825.

DOI：10.1021/om800651z

The coordination chemistry of new fluorinated dialkoxy-diimino ligands onto Al(III) centers has been studied. Diimino-diols (CF(3))(2)C(OH)CR(2)(1)C(R(2))=N- R(3)-N=C(R(2))CR(2)(1)C(OH)(CF(3))(2) ({ON(Et)NO}H(2), R(1) = H, R(2) = Me, R(3) = C(2)H(4); {ON(Cy)NO}H(2), R(1) = H, R(2) = Me, R(3) = trans-1,2-cyclohexyl; {(Me)ON(Et)NO}H(2), R(1) = Me, R(2) = iPr, R(3) = C(2)H(4)) react selectively with AlMe(3), AlMe(2)Cl, and Al(OiPr)(3) to give the corresponding complexes {ON(Et)NO}AlX (X = Me, 1; Cl, 2; OiPr, 3), {ON(Cy)NO}AlX (X = Me, 5; Cl, 6; OiPr, 7), and {(Me)ON(Et)NO}AlX (X = Me, 8; Cl, 9) with concomitant alkane or alcohol elimination, respectively. Single-crystal X-ray diffraction studies revealed that complexes 2, 5, 7, 8, and 9 are mononuclear in the solid state with distorted trigonal-bipyramidal to square-pyramidal geometries. Complexes 1-9 were also characterized in CD(2)Cl(2) solution by (1)H, (13)C, and (19)F NMR spectroscopy. Only one symmetric isomer was observed for complexes 1-7, but mixtures of two isomers (one symmetric, one dissymmetric on the NMR time scale) were observed for complexes 8 and 9. The Al-OiPr complexes 3 and 7 are effective initiators for the ring-opening polymerization of E-caprolactone and racemic lactide, giving polymers with high molecular weights (M(n) up to 37 500 g mol(-1)) and relatively narrow polydispersities (M(w)/M(n) = 1.08-1.91). The PLAs produced, both under slurry or melt conditions, with either achiral complex 3 or chiral complex 7, have a highly isotactic-enriched stereoblock microstructure (P(meso) = 0.87).

• 出版日期2008-11-24