p-tert-butylcalix[4]arene complexes of molybdenum and tungsten

Reactivity of the calixarene methylene C-H bond and the facile migration of the metal around the phenolic rim of the calixarene

Daniela Buccella, Gerard Parkin

Research output: Contribution to journalArticle

Abstract

p-tert-Butylcalix[4]arene, [CalixBut(OH)4], reacts with Mo(PMe3)6 and W(PMe3)42-CH2PMe2)H to yield compounds of composition {[CalixBut(OH)2(O)2]M(PMe3) 3H2} which exhibit unprecedented use of a C-H bond of a calixarene methylene group as a binding functionality in the form of agostic and alkyl hydride derivatives. Thus, X-ray diffraction studies demonstrate that, in the solid state, the molybdenum complex [CalixBut(OH) 2(O)2]Mo(PMe3)3H2 exists as an agostic derivative with a Mo⋯H-C interaction, whereas the tungsten complex exists as a metallated trihydride [Calix-HBut(OH) 2(O)2]W(PMe3)3H3. Solution 1H NMR spectroscopic studies, however, provide evidence that [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 is in equilibrium with its agostic isomer [Calix But(OH)2(O)2]W(PMe3) 3H2. Dynamic NMR spectroscopy also indicates that the [M(PMe3)3H2] fragments of both the molybdenum and tungsten complexes [CalixBut(OH)2(O) 2]M(PMe3)3H2 migrate rapidly around the phenolic rim of the calixarene on the NMR time scale, an observation that is in accord with incorporation of deuterium into the methylene endo positions upon treatment of the isomeric mixture of [CalixBut(OH) 2(O)2]W(PMe3)3H2 and [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 with D2. Treatment of {[Calix But(OH)2(O)2]W(PMe3) 3H2} with Ph2C2 gives the alkylidene complex [CalixBut(O)4]W=C(Ph)Ar [Ar = PhCC(Ph)CH 2Ph].

Original languageEnglish (US)
Pages (from-to)16358-16364
Number of pages7
JournalJournal of the American Chemical Society
Volume128
Issue number50
DOIs
StatePublished - Dec 20 2006

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Calixarenes
Tungsten
Molybdenum
Metals
Nuclear magnetic resonance
Derivatives
Deuterium
Hydrides
X-Ray Diffraction
Isomers
Nuclear magnetic resonance spectroscopy
Magnetic Resonance Spectroscopy
Observation
X ray diffraction
Chemical analysis

ASJC Scopus subject areas

  • Chemistry(all)

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@article{aae3f98a180041f4a82d8e1af6d0fa43,
title = "p-tert-butylcalix[4]arene complexes of molybdenum and tungsten: Reactivity of the calixarene methylene C-H bond and the facile migration of the metal around the phenolic rim of the calixarene",
abstract = "p-tert-Butylcalix[4]arene, [CalixBut(OH)4], reacts with Mo(PMe3)6 and W(PMe3)4(η 2-CH2PMe2)H to yield compounds of composition {[CalixBut(OH)2(O)2]M(PMe3) 3H2} which exhibit unprecedented use of a C-H bond of a calixarene methylene group as a binding functionality in the form of agostic and alkyl hydride derivatives. Thus, X-ray diffraction studies demonstrate that, in the solid state, the molybdenum complex [CalixBut(OH) 2(O)2]Mo(PMe3)3H2 exists as an agostic derivative with a Mo⋯H-C interaction, whereas the tungsten complex exists as a metallated trihydride [Calix-HBut(OH) 2(O)2]W(PMe3)3H3. Solution 1H NMR spectroscopic studies, however, provide evidence that [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 is in equilibrium with its agostic isomer [Calix But(OH)2(O)2]W(PMe3) 3H2. Dynamic NMR spectroscopy also indicates that the [M(PMe3)3H2] fragments of both the molybdenum and tungsten complexes [CalixBut(OH)2(O) 2]M(PMe3)3H2 migrate rapidly around the phenolic rim of the calixarene on the NMR time scale, an observation that is in accord with incorporation of deuterium into the methylene endo positions upon treatment of the isomeric mixture of [CalixBut(OH) 2(O)2]W(PMe3)3H2 and [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 with D2. Treatment of {[Calix But(OH)2(O)2]W(PMe3) 3H2} with Ph2C2 gives the alkylidene complex [CalixBut(O)4]W=C(Ph)Ar [Ar = PhCC(Ph)CH 2Ph].",
author = "Daniela Buccella and Gerard Parkin",
year = "2006",
month = "12",
day = "20",
doi = "10.1021/ja066457b",
language = "English (US)",
volume = "128",
pages = "16358--16364",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "50",

}

TY - JOUR

T1 - p-tert-butylcalix[4]arene complexes of molybdenum and tungsten

T2 - Reactivity of the calixarene methylene C-H bond and the facile migration of the metal around the phenolic rim of the calixarene

AU - Buccella, Daniela

AU - Parkin, Gerard

PY - 2006/12/20

Y1 - 2006/12/20

N2 - p-tert-Butylcalix[4]arene, [CalixBut(OH)4], reacts with Mo(PMe3)6 and W(PMe3)4(η 2-CH2PMe2)H to yield compounds of composition {[CalixBut(OH)2(O)2]M(PMe3) 3H2} which exhibit unprecedented use of a C-H bond of a calixarene methylene group as a binding functionality in the form of agostic and alkyl hydride derivatives. Thus, X-ray diffraction studies demonstrate that, in the solid state, the molybdenum complex [CalixBut(OH) 2(O)2]Mo(PMe3)3H2 exists as an agostic derivative with a Mo⋯H-C interaction, whereas the tungsten complex exists as a metallated trihydride [Calix-HBut(OH) 2(O)2]W(PMe3)3H3. Solution 1H NMR spectroscopic studies, however, provide evidence that [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 is in equilibrium with its agostic isomer [Calix But(OH)2(O)2]W(PMe3) 3H2. Dynamic NMR spectroscopy also indicates that the [M(PMe3)3H2] fragments of both the molybdenum and tungsten complexes [CalixBut(OH)2(O) 2]M(PMe3)3H2 migrate rapidly around the phenolic rim of the calixarene on the NMR time scale, an observation that is in accord with incorporation of deuterium into the methylene endo positions upon treatment of the isomeric mixture of [CalixBut(OH) 2(O)2]W(PMe3)3H2 and [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 with D2. Treatment of {[Calix But(OH)2(O)2]W(PMe3) 3H2} with Ph2C2 gives the alkylidene complex [CalixBut(O)4]W=C(Ph)Ar [Ar = PhCC(Ph)CH 2Ph].

AB - p-tert-Butylcalix[4]arene, [CalixBut(OH)4], reacts with Mo(PMe3)6 and W(PMe3)4(η 2-CH2PMe2)H to yield compounds of composition {[CalixBut(OH)2(O)2]M(PMe3) 3H2} which exhibit unprecedented use of a C-H bond of a calixarene methylene group as a binding functionality in the form of agostic and alkyl hydride derivatives. Thus, X-ray diffraction studies demonstrate that, in the solid state, the molybdenum complex [CalixBut(OH) 2(O)2]Mo(PMe3)3H2 exists as an agostic derivative with a Mo⋯H-C interaction, whereas the tungsten complex exists as a metallated trihydride [Calix-HBut(OH) 2(O)2]W(PMe3)3H3. Solution 1H NMR spectroscopic studies, however, provide evidence that [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 is in equilibrium with its agostic isomer [Calix But(OH)2(O)2]W(PMe3) 3H2. Dynamic NMR spectroscopy also indicates that the [M(PMe3)3H2] fragments of both the molybdenum and tungsten complexes [CalixBut(OH)2(O) 2]M(PMe3)3H2 migrate rapidly around the phenolic rim of the calixarene on the NMR time scale, an observation that is in accord with incorporation of deuterium into the methylene endo positions upon treatment of the isomeric mixture of [CalixBut(OH) 2(O)2]W(PMe3)3H2 and [Calix-HBut(OH)2(O)2]W(PMe3) 3H3 with D2. Treatment of {[Calix But(OH)2(O)2]W(PMe3) 3H2} with Ph2C2 gives the alkylidene complex [CalixBut(O)4]W=C(Ph)Ar [Ar = PhCC(Ph)CH 2Ph].

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DO - 10.1021/ja066457b

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VL - 128

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SN - 0002-7863

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