TY - JOUR

T1 - Synthesis and characterization of a series of bis(oxo/thiophosphinic)diamido yttrium complexes and their application as initiators for lactide ring-opening polymerization

AU - Platel, Rachel H.

AU - Hodgson, Linda M.

AU - White, Andrew J. P.

AU - Williams, Charlotte K.

PY - 2007/9/24

Y1 - 2007/9/24

N2 - The syntheses, structures, and lactide polymerization initiation are reported for a series of novel [{N,N'-1,3-bis(P,P'-di-isopropyloxophosphinic)-2,2-dimethylpropylenediamido}(amido)yttrium] complexes and contrasted with [{N,N'-1,3-bis(P,P'-di-isopropylthiophosphinic)-2,2-dimethylamido}{bis(trimethylsilyl)-amido}yttrium]. The syntheses of the novel [{N,N'-1,3-bis(P,P'-di-isopropyloxo/thiophosphinic)-2,2-dimethylpropylenediamido}(amido)yttrium] complexes were achieved in excellent yields by reaction of the N,N'-1,3-bis(P,P'-di-isopropyloxo/thiophosphinic)-2,2-dimethylpropylenediamine ligands with [Y(NR(2))(3)center dot xTHF] (R = SiMe(3), SiMe(2)H, i-Pr, x = 0, 2). The new complexes were characterized by NMR and IR spectroscopies, elemental analyses, and for R = SiMe(2)H X-ray crystallography. The solution and solid-state structures were compared using 21) NMR techniques and in particular using pulsed gradient spin echo spectroscopy (PGSE) to derive the solution hydrodynamic radius and compare it to that calculated from the X-ray crystal structure: the [{N,N'-bis(P,P'-di-isopropyloxophosphinic)-2,2-dimethylpropylenediamido}(amido)yttrium] complexes were all dimeric in both the solid state and solution. They showed unusual structures where each ligand has one oxophosphinic group bonded to a single yttrium center and one oxophosphinic group bonded to two yttrium centers. The new complexes were tested as lactide polymerization initiators; they all showed very high activities. The degree of polymerization control exerted by the novel initiators was related to the size of the initiating amide group and the structure of the complex.

AB - The syntheses, structures, and lactide polymerization initiation are reported for a series of novel [{N,N'-1,3-bis(P,P'-di-isopropyloxophosphinic)-2,2-dimethylpropylenediamido}(amido)yttrium] complexes and contrasted with [{N,N'-1,3-bis(P,P'-di-isopropylthiophosphinic)-2,2-dimethylamido}{bis(trimethylsilyl)-amido}yttrium]. The syntheses of the novel [{N,N'-1,3-bis(P,P'-di-isopropyloxo/thiophosphinic)-2,2-dimethylpropylenediamido}(amido)yttrium] complexes were achieved in excellent yields by reaction of the N,N'-1,3-bis(P,P'-di-isopropyloxo/thiophosphinic)-2,2-dimethylpropylenediamine ligands with [Y(NR(2))(3)center dot xTHF] (R = SiMe(3), SiMe(2)H, i-Pr, x = 0, 2). The new complexes were characterized by NMR and IR spectroscopies, elemental analyses, and for R = SiMe(2)H X-ray crystallography. The solution and solid-state structures were compared using 21) NMR techniques and in particular using pulsed gradient spin echo spectroscopy (PGSE) to derive the solution hydrodynamic radius and compare it to that calculated from the X-ray crystal structure: the [{N,N'-bis(P,P'-di-isopropyloxophosphinic)-2,2-dimethylpropylenediamido}(amido)yttrium] complexes were all dimeric in both the solid state and solution. They showed unusual structures where each ligand has one oxophosphinic group bonded to a single yttrium center and one oxophosphinic group bonded to two yttrium centers. The new complexes were tested as lactide polymerization initiators; they all showed very high activities. The degree of polymerization control exerted by the novel initiators was related to the size of the initiating amide group and the structure of the complex.

KW - CATALYSTS

KW - COORDINATION CHEMISTRY

KW - X-RAY STRUCTURE

KW - INTRAMOLECULAR ALKENE HYDROAMINATION

KW - LIGANDS

KW - DERIVATIVES

KW - EPSILON-CAPROLACTONE

KW - GROUP-3 METAL-COMPLEXES

KW - DL-LACTIDE

KW - STRUCTURAL-CHARACTERIZATION

U2 - 10.1021/om7004194

DO - 10.1021/om7004194

M3 - Journal article

VL - 26

SP - 4955

EP - 4963

JO - Organometallics

JF - Organometallics

SN - 0276-7333

IS - 20

ER -