4-Methoxy- and 4-cyano-substituted lithium aryloxides: electronic effects of substituents on aggregation

D J MacDougall, B C Noll, A R Kennedy, K W Henderson

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The para-substituted lithium aryloxides [{4-NC-C6H4OLi center dot(Pyr)(2)}(2)center dot Pyr] 1a, [{4-NC-C6H4OLi center dot(THF)(2)}(2)] 1b, [{4-MeO-C6H4OLi center dot Pyr}4] 2a, [4-MeO-C6H4OLi center dot(THF)(n)] 2b, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot( Pyr)(2)}(infinity)] 3a, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(2)}(infinity)] 3b, [{4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot Pyr}(2)center dot(Pyr)(2)] 4a, and [4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(n)] 4b were prepared by the direct deprotonation of the corresponding phenol with an alkyllithium base ( BuLi or MeLi) in the appropriate solvent, either pyridine or THF. All compounds were characterized by H-1 and C-13 NMR spectroscopy, and the crystal structures of 1a, 1b, 2a, 3a, 3b and 4a were elucidated. The cyano derivatives 1a and 1b adopt discrete tetrasolvated Li2O2 ring dimers whereas the methoxy analogue 2a crystallizes as a tetrasolvated molecular tetramer with a pseudo cubic Li4O4 core. The sterically encumbered cyano derivatives 3a and 3b form isostructural 1D polymeric chains of monomers via bridging of the phenolate ligands through Li center dot center dot center dot NC and Li - O contacts. In comparison, the crystal structure of the methoxy counterpart 4a is a disolvated molecular Li2O2 ring dimer. Solution NMR spectroscopic studies of 1 - 4 in d(5)-pyridine and d(8)-THF indicate that the methoxy complexes are more highly aggregated than the cyano derivatives, consistent with the solid-state studies. Ab initio molecular orbital calculations at the HF/6-31G* level of theory indicate that the origin of the aggregation state variations between the cyano and methoxy complexes is due to electronic effects.

LanguageEnglish
Pages1875-1884
Number of pages10
JournalDalton Transactions
Issue number15
DOIs
Publication statusPublished - 2006

Fingerprint

Lithium
Agglomeration
Derivatives
Dimers
Crystal structure
Orbital calculations
Deprotonation
Molecular orbitals
Phenol
Nuclear magnetic resonance spectroscopy
Monomers
Nuclear magnetic resonance
Ligands
pyridine

Keywords

  • molecular-orbital methods
  • polar aprotic solvents
  • metal organic frameworks
  • x-ray structure
  • coordination polymers
  • crystal structures
  • structural systematics

Cite this

@article{af0fdd8515f4431cb74984464129d99a,
title = "4-Methoxy- and 4-cyano-substituted lithium aryloxides: electronic effects of substituents on aggregation",
abstract = "The para-substituted lithium aryloxides [{4-NC-C6H4OLi center dot(Pyr)(2)}(2)center dot Pyr] 1a, [{4-NC-C6H4OLi center dot(THF)(2)}(2)] 1b, [{4-MeO-C6H4OLi center dot Pyr}4] 2a, [4-MeO-C6H4OLi center dot(THF)(n)] 2b, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot( Pyr)(2)}(infinity)] 3a, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(2)}(infinity)] 3b, [{4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot Pyr}(2)center dot(Pyr)(2)] 4a, and [4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(n)] 4b were prepared by the direct deprotonation of the corresponding phenol with an alkyllithium base ( BuLi or MeLi) in the appropriate solvent, either pyridine or THF. All compounds were characterized by H-1 and C-13 NMR spectroscopy, and the crystal structures of 1a, 1b, 2a, 3a, 3b and 4a were elucidated. The cyano derivatives 1a and 1b adopt discrete tetrasolvated Li2O2 ring dimers whereas the methoxy analogue 2a crystallizes as a tetrasolvated molecular tetramer with a pseudo cubic Li4O4 core. The sterically encumbered cyano derivatives 3a and 3b form isostructural 1D polymeric chains of monomers via bridging of the phenolate ligands through Li center dot center dot center dot NC and Li - O contacts. In comparison, the crystal structure of the methoxy counterpart 4a is a disolvated molecular Li2O2 ring dimer. Solution NMR spectroscopic studies of 1 - 4 in d(5)-pyridine and d(8)-THF indicate that the methoxy complexes are more highly aggregated than the cyano derivatives, consistent with the solid-state studies. Ab initio molecular orbital calculations at the HF/6-31G* level of theory indicate that the origin of the aggregation state variations between the cyano and methoxy complexes is due to electronic effects.",
keywords = "molecular-orbital methods, polar aprotic solvents, metal organic frameworks, x-ray structure, coordination polymers, crystal structures, structural systematics",
author = "MacDougall, {D J} and Noll, {B C} and Kennedy, {A R} and Henderson, {K W}",
year = "2006",
doi = "10.1039/b515011f",
language = "English",
pages = "1875--1884",
journal = "Dalton Transactions",
issn = "1477-9226",
number = "15",

}

4-Methoxy- and 4-cyano-substituted lithium aryloxides: electronic effects of substituents on aggregation. / MacDougall, D J ; Noll, B C ; Kennedy, A R ; Henderson, K W .

In: Dalton Transactions, No. 15, 2006, p. 1875-1884.

Research output: Contribution to journalArticle

TY - JOUR

T1 - 4-Methoxy- and 4-cyano-substituted lithium aryloxides: electronic effects of substituents on aggregation

AU - MacDougall, D J

AU - Noll, B C

AU - Kennedy, A R

AU - Henderson, K W

PY - 2006

Y1 - 2006

N2 - The para-substituted lithium aryloxides [{4-NC-C6H4OLi center dot(Pyr)(2)}(2)center dot Pyr] 1a, [{4-NC-C6H4OLi center dot(THF)(2)}(2)] 1b, [{4-MeO-C6H4OLi center dot Pyr}4] 2a, [4-MeO-C6H4OLi center dot(THF)(n)] 2b, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot( Pyr)(2)}(infinity)] 3a, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(2)}(infinity)] 3b, [{4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot Pyr}(2)center dot(Pyr)(2)] 4a, and [4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(n)] 4b were prepared by the direct deprotonation of the corresponding phenol with an alkyllithium base ( BuLi or MeLi) in the appropriate solvent, either pyridine or THF. All compounds were characterized by H-1 and C-13 NMR spectroscopy, and the crystal structures of 1a, 1b, 2a, 3a, 3b and 4a were elucidated. The cyano derivatives 1a and 1b adopt discrete tetrasolvated Li2O2 ring dimers whereas the methoxy analogue 2a crystallizes as a tetrasolvated molecular tetramer with a pseudo cubic Li4O4 core. The sterically encumbered cyano derivatives 3a and 3b form isostructural 1D polymeric chains of monomers via bridging of the phenolate ligands through Li center dot center dot center dot NC and Li - O contacts. In comparison, the crystal structure of the methoxy counterpart 4a is a disolvated molecular Li2O2 ring dimer. Solution NMR spectroscopic studies of 1 - 4 in d(5)-pyridine and d(8)-THF indicate that the methoxy complexes are more highly aggregated than the cyano derivatives, consistent with the solid-state studies. Ab initio molecular orbital calculations at the HF/6-31G* level of theory indicate that the origin of the aggregation state variations between the cyano and methoxy complexes is due to electronic effects.

AB - The para-substituted lithium aryloxides [{4-NC-C6H4OLi center dot(Pyr)(2)}(2)center dot Pyr] 1a, [{4-NC-C6H4OLi center dot(THF)(2)}(2)] 1b, [{4-MeO-C6H4OLi center dot Pyr}4] 2a, [4-MeO-C6H4OLi center dot(THF)(n)] 2b, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot( Pyr)(2)}(infinity)] 3a, [{4-NC-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(2)}(infinity)] 3b, [{4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot Pyr}(2)center dot(Pyr)(2)] 4a, and [4-MeO-2,6-(t-Bu)(2)-C6H2OLi center dot(THF)(n)] 4b were prepared by the direct deprotonation of the corresponding phenol with an alkyllithium base ( BuLi or MeLi) in the appropriate solvent, either pyridine or THF. All compounds were characterized by H-1 and C-13 NMR spectroscopy, and the crystal structures of 1a, 1b, 2a, 3a, 3b and 4a were elucidated. The cyano derivatives 1a and 1b adopt discrete tetrasolvated Li2O2 ring dimers whereas the methoxy analogue 2a crystallizes as a tetrasolvated molecular tetramer with a pseudo cubic Li4O4 core. The sterically encumbered cyano derivatives 3a and 3b form isostructural 1D polymeric chains of monomers via bridging of the phenolate ligands through Li center dot center dot center dot NC and Li - O contacts. In comparison, the crystal structure of the methoxy counterpart 4a is a disolvated molecular Li2O2 ring dimer. Solution NMR spectroscopic studies of 1 - 4 in d(5)-pyridine and d(8)-THF indicate that the methoxy complexes are more highly aggregated than the cyano derivatives, consistent with the solid-state studies. Ab initio molecular orbital calculations at the HF/6-31G* level of theory indicate that the origin of the aggregation state variations between the cyano and methoxy complexes is due to electronic effects.

KW - molecular-orbital methods

KW - polar aprotic solvents

KW - metal organic frameworks

KW - x-ray structure

KW - coordination polymers

KW - crystal structures

KW - structural systematics

U2 - 10.1039/b515011f

DO - 10.1039/b515011f

M3 - Article

SP - 1875

EP - 1884

JO - Dalton Transactions

T2 - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 15

ER -