Aluminium complexes of bidentate N,O- and N,N-ligands derived from oxidative functionalization of amido phosphines: Synthesis, structure and reactivity

Lan Chang Liang, Feng Yi Chen, Mei Hui Huang, Liang Chien Cheng, Chun Wei Li, Hon Man Lee

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

A series of amido phosphinoxide and amido phosphinimine ligands that are electronic variations of monoanionic N,O- and N,N-ketiminates have been prepared and employed to examine the coordination chemistry of aluminium. Oxidation of the previously established N-(2-diphenylphosphinophenyl)-2,6-dialkylaniline in the presence of H2O2 or organic azides RN3 (R = 2,6-C6H3iPr2, SiMe3) led to phosphinoxides (H[NO] 1a-b) and phosphinimines (H[NN] 1c-d), respectively. Alkane elimination reactions of these protio-ligand precursors with trialkylaluminium in toluene or pentane solutions afforded cleanly the corresponding organoaluminium complexes, including dimethyl 2a-d, diethyl 3a-d and diisobutyl derivatives 4a-b and 4d. Solution NMR studies revealed Cs symmetry for these organoaluminium species, in which the α-hydrogen atoms are all diastereotopic. The correlation between the steric congestion of these molecules and the degree of resolution of the multiplet signals corresponding to the diastereotopic α-hydrogen atoms observed by the 1H NMR spectroscopy is of particular interest. Dichloroaluminium complexes 5c-d were prepared in high yields by protonolysis of MeAlCl2 with 1c-d. Single-crystal X-ray diffraction analyses of 2c-d, 3a, 3d, 4a, and 4d elucidated a mononuclear, distorted tetrahedral core for all of these aluminium species. Interestingly, complexes 2c-d are active initiators for catalytic ring-opening oligomerization of ε-caprolactone, whereas 2a-b are rather inactive, highlighting the significance of the steric hindrance imposed by the amido phosphinimine ligands, as compared to that imposed by the phosphinoxide counterparts.

Original languageEnglish
Pages (from-to)9941-9951
Number of pages11
JournalDalton Transactions
Volume39
Issue number41
DOIs
Publication statusPublished - 2010 Nov 7

Fingerprint

Phosphines
Aluminum
Ligands
Hydrogen
Atoms
Oligomerization
Alkanes
Azides
Toluene
Nuclear magnetic resonance spectroscopy
Nuclear magnetic resonance
Single crystals
Derivatives
X ray diffraction
Oxidation
Molecules

All Science Journal Classification (ASJC) codes

  • Inorganic Chemistry

Cite this

Liang, Lan Chang ; Chen, Feng Yi ; Huang, Mei Hui ; Cheng, Liang Chien ; Li, Chun Wei ; Lee, Hon Man. / Aluminium complexes of bidentate N,O- and N,N-ligands derived from oxidative functionalization of amido phosphines : Synthesis, structure and reactivity. In: Dalton Transactions. 2010 ; Vol. 39, No. 41. pp. 9941-9951.
@article{0b783022374348f98c5f73f0d6df7c44,
title = "Aluminium complexes of bidentate N,O- and N,N-ligands derived from oxidative functionalization of amido phosphines: Synthesis, structure and reactivity",
abstract = "A series of amido phosphinoxide and amido phosphinimine ligands that are electronic variations of monoanionic N,O- and N,N-ketiminates have been prepared and employed to examine the coordination chemistry of aluminium. Oxidation of the previously established N-(2-diphenylphosphinophenyl)-2,6-dialkylaniline in the presence of H2O2 or organic azides RN3 (R = 2,6-C6H3iPr2, SiMe3) led to phosphinoxides (H[NO] 1a-b) and phosphinimines (H[NN] 1c-d), respectively. Alkane elimination reactions of these protio-ligand precursors with trialkylaluminium in toluene or pentane solutions afforded cleanly the corresponding organoaluminium complexes, including dimethyl 2a-d, diethyl 3a-d and diisobutyl derivatives 4a-b and 4d. Solution NMR studies revealed Cs symmetry for these organoaluminium species, in which the α-hydrogen atoms are all diastereotopic. The correlation between the steric congestion of these molecules and the degree of resolution of the multiplet signals corresponding to the diastereotopic α-hydrogen atoms observed by the 1H NMR spectroscopy is of particular interest. Dichloroaluminium complexes 5c-d were prepared in high yields by protonolysis of MeAlCl2 with 1c-d. Single-crystal X-ray diffraction analyses of 2c-d, 3a, 3d, 4a, and 4d elucidated a mononuclear, distorted tetrahedral core for all of these aluminium species. Interestingly, complexes 2c-d are active initiators for catalytic ring-opening oligomerization of ε-caprolactone, whereas 2a-b are rather inactive, highlighting the significance of the steric hindrance imposed by the amido phosphinimine ligands, as compared to that imposed by the phosphinoxide counterparts.",
author = "Liang, {Lan Chang} and Chen, {Feng Yi} and Huang, {Mei Hui} and Cheng, {Liang Chien} and Li, {Chun Wei} and Lee, {Hon Man}",
year = "2010",
month = "11",
day = "7",
doi = "10.1039/c0dt00418a",
language = "English",
volume = "39",
pages = "9941--9951",
journal = "Dalton Transactions",
issn = "1477-9226",
publisher = "Royal Society of Chemistry",
number = "41",

}

Aluminium complexes of bidentate N,O- and N,N-ligands derived from oxidative functionalization of amido phosphines : Synthesis, structure and reactivity. / Liang, Lan Chang; Chen, Feng Yi; Huang, Mei Hui; Cheng, Liang Chien; Li, Chun Wei; Lee, Hon Man.

In: Dalton Transactions, Vol. 39, No. 41, 07.11.2010, p. 9941-9951.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Aluminium complexes of bidentate N,O- and N,N-ligands derived from oxidative functionalization of amido phosphines

T2 - Synthesis, structure and reactivity

AU - Liang, Lan Chang

AU - Chen, Feng Yi

AU - Huang, Mei Hui

AU - Cheng, Liang Chien

AU - Li, Chun Wei

AU - Lee, Hon Man

PY - 2010/11/7

Y1 - 2010/11/7

N2 - A series of amido phosphinoxide and amido phosphinimine ligands that are electronic variations of monoanionic N,O- and N,N-ketiminates have been prepared and employed to examine the coordination chemistry of aluminium. Oxidation of the previously established N-(2-diphenylphosphinophenyl)-2,6-dialkylaniline in the presence of H2O2 or organic azides RN3 (R = 2,6-C6H3iPr2, SiMe3) led to phosphinoxides (H[NO] 1a-b) and phosphinimines (H[NN] 1c-d), respectively. Alkane elimination reactions of these protio-ligand precursors with trialkylaluminium in toluene or pentane solutions afforded cleanly the corresponding organoaluminium complexes, including dimethyl 2a-d, diethyl 3a-d and diisobutyl derivatives 4a-b and 4d. Solution NMR studies revealed Cs symmetry for these organoaluminium species, in which the α-hydrogen atoms are all diastereotopic. The correlation between the steric congestion of these molecules and the degree of resolution of the multiplet signals corresponding to the diastereotopic α-hydrogen atoms observed by the 1H NMR spectroscopy is of particular interest. Dichloroaluminium complexes 5c-d were prepared in high yields by protonolysis of MeAlCl2 with 1c-d. Single-crystal X-ray diffraction analyses of 2c-d, 3a, 3d, 4a, and 4d elucidated a mononuclear, distorted tetrahedral core for all of these aluminium species. Interestingly, complexes 2c-d are active initiators for catalytic ring-opening oligomerization of ε-caprolactone, whereas 2a-b are rather inactive, highlighting the significance of the steric hindrance imposed by the amido phosphinimine ligands, as compared to that imposed by the phosphinoxide counterparts.

AB - A series of amido phosphinoxide and amido phosphinimine ligands that are electronic variations of monoanionic N,O- and N,N-ketiminates have been prepared and employed to examine the coordination chemistry of aluminium. Oxidation of the previously established N-(2-diphenylphosphinophenyl)-2,6-dialkylaniline in the presence of H2O2 or organic azides RN3 (R = 2,6-C6H3iPr2, SiMe3) led to phosphinoxides (H[NO] 1a-b) and phosphinimines (H[NN] 1c-d), respectively. Alkane elimination reactions of these protio-ligand precursors with trialkylaluminium in toluene or pentane solutions afforded cleanly the corresponding organoaluminium complexes, including dimethyl 2a-d, diethyl 3a-d and diisobutyl derivatives 4a-b and 4d. Solution NMR studies revealed Cs symmetry for these organoaluminium species, in which the α-hydrogen atoms are all diastereotopic. The correlation between the steric congestion of these molecules and the degree of resolution of the multiplet signals corresponding to the diastereotopic α-hydrogen atoms observed by the 1H NMR spectroscopy is of particular interest. Dichloroaluminium complexes 5c-d were prepared in high yields by protonolysis of MeAlCl2 with 1c-d. Single-crystal X-ray diffraction analyses of 2c-d, 3a, 3d, 4a, and 4d elucidated a mononuclear, distorted tetrahedral core for all of these aluminium species. Interestingly, complexes 2c-d are active initiators for catalytic ring-opening oligomerization of ε-caprolactone, whereas 2a-b are rather inactive, highlighting the significance of the steric hindrance imposed by the amido phosphinimine ligands, as compared to that imposed by the phosphinoxide counterparts.

UR - http://www.scopus.com/inward/record.url?scp=77957888824&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77957888824&partnerID=8YFLogxK

U2 - 10.1039/c0dt00418a

DO - 10.1039/c0dt00418a

M3 - Article

C2 - 20838684

AN - SCOPUS:77957888824

VL - 39

SP - 9941

EP - 9951

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 41

ER -