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 journalArticlepeer-review

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

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Fingerprint Dive into the research topics of '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'. Together they form a unique fingerprint.

Cite this