Four- and five-coordinate magnesium compounds containing ketiminate ligands. Synthesis and characterization of L 2 Mg, L 2 Mg(LH), and L 2 Mg(Py), where L = MeC(O)CHC(NAr)Me

Wen Yi Lee, Hsiang Hua Hsieh, Chun Chin Hsieh, Hon Man Lee, Gene Hsiang Lee, Jui-Hsien Huang, Tsun Cheng Wu, Shiow Huey Chuang

Research output: Contribution to journalArticle

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Abstract

Magnesium complexes containing ketiminate ligands were synthesized and characterized. MgBu 2 reacted readily in toluene with two equiv. of [MeC(O)CHC(NHAr)Me], where Ar = 2,6-diisopropylphenyl, to generate [MeC(O)CHC(NAr)Me] 2 Mg (1) in 43% yield. The four-coordinate magnesium compound 1 is very moisture sensitive and acts as a Lewis acid, accepting one equiv. of Lewis base to form five-coordinate magnesium compounds. Compound [MeC(O)CHC(NAr)Me] 2 Mg[MeC(O)CHC(NHAr)Me] (2) was obtained in 57% yield from the reaction in toluene of MgBu 2 with three equiv. of [MeC(O)CHC(NHAr)Me]. Treatment of 1 with one equiv. of free ketimine ligands [MeC(O)CHC(NHAr)Me] also led to the formation of 2. The bulky η 1 -ketimine of 2 can be replaced with a less bulky Lewis base such as pyridine. Treatment of 1 with excess pyridine in toluene at ambient temperature led to the formation of compound [MeC(O)CHC(NAr)Me] 2 Mg[NC 5 H 5 ] (3) as colorless crystalline solids in 51% yield. Compounds 1, 2, and 3 were characterized by NMR and X-ray crystallography. Compounds 2 and 3 showed no activity toward the polymerization of ε-caprolactone at 25 °C after 3 h. However, when the temperature was increased to 70 °C, compounds 2 and 3 efficiently catalyzed polymerization of ε-caprolactone to generate high molecular weight poly-ε-caprolactones. The polydispersity index (PDI) of these poly-ε-caprolactones is in the range 1.57-3.18.

Original languageEnglish
Pages (from-to)1131-1137
Number of pages7
JournalJournal of Organometallic Chemistry
Volume692
Issue number5
DOIs
Publication statusPublished - 2007 Feb 1

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Magnesium Compounds
Magnesium compounds
magnesium compounds
Toluene
Lewis Bases
toluene
Lewis base
Ligands
Polymerization
Pyridine
ligands
pyridines
synthesis
polymerization
Lewis Acids
Temperature
X ray crystallography
X Ray Crystallography
Polydispersity
moisture

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

@article{d0ae2fdd14d34e2c9679494a66a687ab,
title = "Four- and five-coordinate magnesium compounds containing ketiminate ligands. Synthesis and characterization of L 2 Mg, L 2 Mg(LH), and L 2 Mg(Py), where L = MeC(O)CHC(NAr)Me",
abstract = "Magnesium complexes containing ketiminate ligands were synthesized and characterized. MgBu 2 reacted readily in toluene with two equiv. of [MeC(O)CHC(NHAr)Me], where Ar = 2,6-diisopropylphenyl, to generate [MeC(O)CHC(NAr)Me] 2 Mg (1) in 43{\%} yield. The four-coordinate magnesium compound 1 is very moisture sensitive and acts as a Lewis acid, accepting one equiv. of Lewis base to form five-coordinate magnesium compounds. Compound [MeC(O)CHC(NAr)Me] 2 Mg[MeC(O)CHC(NHAr)Me] (2) was obtained in 57{\%} yield from the reaction in toluene of MgBu 2 with three equiv. of [MeC(O)CHC(NHAr)Me]. Treatment of 1 with one equiv. of free ketimine ligands [MeC(O)CHC(NHAr)Me] also led to the formation of 2. The bulky η 1 -ketimine of 2 can be replaced with a less bulky Lewis base such as pyridine. Treatment of 1 with excess pyridine in toluene at ambient temperature led to the formation of compound [MeC(O)CHC(NAr)Me] 2 Mg[NC 5 H 5 ] (3) as colorless crystalline solids in 51{\%} yield. Compounds 1, 2, and 3 were characterized by NMR and X-ray crystallography. Compounds 2 and 3 showed no activity toward the polymerization of ε-caprolactone at 25 °C after 3 h. However, when the temperature was increased to 70 °C, compounds 2 and 3 efficiently catalyzed polymerization of ε-caprolactone to generate high molecular weight poly-ε-caprolactones. The polydispersity index (PDI) of these poly-ε-caprolactones is in the range 1.57-3.18.",
author = "Lee, {Wen Yi} and Hsieh, {Hsiang Hua} and Hsieh, {Chun Chin} and Lee, {Hon Man} and Lee, {Gene Hsiang} and Jui-Hsien Huang and Wu, {Tsun Cheng} and Chuang, {Shiow Huey}",
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doi = "10.1016/j.jorganchem.2006.11.015",
language = "English",
volume = "692",
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journal = "Journal of Organometallic Chemistry",
issn = "0022-328X",
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Four- and five-coordinate magnesium compounds containing ketiminate ligands. Synthesis and characterization of L 2 Mg, L 2 Mg(LH), and L 2 Mg(Py), where L = MeC(O)CHC(NAr)Me . / Lee, Wen Yi; Hsieh, Hsiang Hua; Hsieh, Chun Chin; Lee, Hon Man; Lee, Gene Hsiang; Huang, Jui-Hsien; Wu, Tsun Cheng; Chuang, Shiow Huey.

In: Journal of Organometallic Chemistry, Vol. 692, No. 5, 01.02.2007, p. 1131-1137.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Four- and five-coordinate magnesium compounds containing ketiminate ligands. Synthesis and characterization of L 2 Mg, L 2 Mg(LH), and L 2 Mg(Py), where L = MeC(O)CHC(NAr)Me

AU - Lee, Wen Yi

AU - Hsieh, Hsiang Hua

AU - Hsieh, Chun Chin

AU - Lee, Hon Man

AU - Lee, Gene Hsiang

AU - Huang, Jui-Hsien

AU - Wu, Tsun Cheng

AU - Chuang, Shiow Huey

PY - 2007/2/1

Y1 - 2007/2/1

N2 - Magnesium complexes containing ketiminate ligands were synthesized and characterized. MgBu 2 reacted readily in toluene with two equiv. of [MeC(O)CHC(NHAr)Me], where Ar = 2,6-diisopropylphenyl, to generate [MeC(O)CHC(NAr)Me] 2 Mg (1) in 43% yield. The four-coordinate magnesium compound 1 is very moisture sensitive and acts as a Lewis acid, accepting one equiv. of Lewis base to form five-coordinate magnesium compounds. Compound [MeC(O)CHC(NAr)Me] 2 Mg[MeC(O)CHC(NHAr)Me] (2) was obtained in 57% yield from the reaction in toluene of MgBu 2 with three equiv. of [MeC(O)CHC(NHAr)Me]. Treatment of 1 with one equiv. of free ketimine ligands [MeC(O)CHC(NHAr)Me] also led to the formation of 2. The bulky η 1 -ketimine of 2 can be replaced with a less bulky Lewis base such as pyridine. Treatment of 1 with excess pyridine in toluene at ambient temperature led to the formation of compound [MeC(O)CHC(NAr)Me] 2 Mg[NC 5 H 5 ] (3) as colorless crystalline solids in 51% yield. Compounds 1, 2, and 3 were characterized by NMR and X-ray crystallography. Compounds 2 and 3 showed no activity toward the polymerization of ε-caprolactone at 25 °C after 3 h. However, when the temperature was increased to 70 °C, compounds 2 and 3 efficiently catalyzed polymerization of ε-caprolactone to generate high molecular weight poly-ε-caprolactones. The polydispersity index (PDI) of these poly-ε-caprolactones is in the range 1.57-3.18.

AB - Magnesium complexes containing ketiminate ligands were synthesized and characterized. MgBu 2 reacted readily in toluene with two equiv. of [MeC(O)CHC(NHAr)Me], where Ar = 2,6-diisopropylphenyl, to generate [MeC(O)CHC(NAr)Me] 2 Mg (1) in 43% yield. The four-coordinate magnesium compound 1 is very moisture sensitive and acts as a Lewis acid, accepting one equiv. of Lewis base to form five-coordinate magnesium compounds. Compound [MeC(O)CHC(NAr)Me] 2 Mg[MeC(O)CHC(NHAr)Me] (2) was obtained in 57% yield from the reaction in toluene of MgBu 2 with three equiv. of [MeC(O)CHC(NHAr)Me]. Treatment of 1 with one equiv. of free ketimine ligands [MeC(O)CHC(NHAr)Me] also led to the formation of 2. The bulky η 1 -ketimine of 2 can be replaced with a less bulky Lewis base such as pyridine. Treatment of 1 with excess pyridine in toluene at ambient temperature led to the formation of compound [MeC(O)CHC(NAr)Me] 2 Mg[NC 5 H 5 ] (3) as colorless crystalline solids in 51% yield. Compounds 1, 2, and 3 were characterized by NMR and X-ray crystallography. Compounds 2 and 3 showed no activity toward the polymerization of ε-caprolactone at 25 °C after 3 h. However, when the temperature was increased to 70 °C, compounds 2 and 3 efficiently catalyzed polymerization of ε-caprolactone to generate high molecular weight poly-ε-caprolactones. The polydispersity index (PDI) of these poly-ε-caprolactones is in the range 1.57-3.18.

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