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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U2 - 10.1021/ja066457b
DO - 10.1021/ja066457b
M3 - Article
C2 - 17165791
AN - SCOPUS:33845591352
SN - 0002-7863
VL - 128
SP - 16358
EP - 16364
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 50
ER -