Alkyne Adducts of Ditungsten Tetrapivalate: [W2(2-O2CtBu)4(
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- 作者：Matthew J. Byrnes ; Malcolm H. Chisholm ; Judith Gallucci ; and Paul J. Wilson
- 刊名：Organometallics
- 出版年：2002
- 出版时间：May 27, 2002
- 年：2002
- 卷：21
- 期：11
- 页码：2240 - 2247
- 全文大小：366K
- 年卷期：v.21,no.11(May 27, 2002)
- ISSN：1520-6041
文摘
Aromatic hydrocarbon solutions of [W2(O2CtBu)4] react with alkynes RC
f">CR' to giveadducts of the formula [W2(
fchars/kappa.gif" BORDER=0 >2-O2CtBu)4(
f">-RCCR')2], where R = R' = Me, Et, Ph and R = Me,R' = Ph, as orange to purple air-stable, hydrocarbon-soluble, crystalline solids which havebeen characterized by infrared, NMR spectroscopy, and mass spectrometry. The single-crystalX-ray structures have also been obtained for R = R' = Me and R = Me, R' = Ph. In bothstructures, there are a pair of perpendicularly bridged alkyne ligands with central C-Cdistances of ca. 1.34 Å and a W-W bond of ca. 2.5 Å. The crystallographically characterizedmolecules have virtual C2h symmetry, and in solution, the NMR data are consistent withthe presence of this isomer and a second having D2 symmetry. The two isomers can be relatedto meso and fchars/Delta.gif" BORDER=0 >/
f"> isomers of an edge-bridged octahedral unit containing four chelates:[(chelate)2M(f">-X)2M(chelate)2], where X represents the central position of the f">-perpendicularalkyne. The isomerization in solution was found to be intramolecular and solvent-assisted,with THF-d8 > benzene-d6 
f"> toluene-d8 > CD2Cl2, and can be catalyzed by the addition oftBuCO2H. The electronic structure and bonding in these compounds have been investigatedusing density functional theory calculations on the model compounds D2 and C2h [W2(fchars/kappa.gif" BORDER=0 >2-O2CH)4(f">-HCCH)2]. These calculational results lend credence to the notion that there is a W-Wbond of order 2.
f">CR' to giveadducts of the formula [W2(fchars/kappa.gif" BORDER=0 >2-O2CtBu)4(f">-RCCR')2], where R = R' = Me, Et, Ph and R = Me,R' = Ph, as orange to purple air-stable, hydrocarbon-soluble, crystalline solids which havebeen characterized by infrared, NMR spectroscopy, and mass spectrometry. The single-crystalX-ray structures have also been obtained for R = R' = Me and R = Me, R' = Ph. In bothstructures, there are a pair of perpendicularly bridged alkyne ligands with central C-Cdistances of ca. 1.34 Å and a W-W bond of ca. 2.5 Å. The crystallographically characterizedmolecules have virtual C2h symmetry, and in solution, the NMR data are consistent withthe presence of this isomer and a second having D2 symmetry. The two isomers can be relatedto meso and fchars/Delta.gif" BORDER=0 >/f"> isomers of an edge-bridged octahedral unit containing four chelates:[(chelate)2M(f">-X)2M(chelate)2], where X represents the central position of the f">-perpendicularalkyne. The isomerization in solution was found to be intramolecular and solvent-assisted,with THF-d8 > benzene-d6 f"> toluene-d8 > CD2Cl2, and can be catalyzed by the addition oftBuCO2H. The electronic structure and bonding in these compounds have been investigatedusing density functional theory calculations on the model compounds D2 and C2h [W2(fchars/kappa.gif" BORDER=0 >2-O2CH)4(f">-HCCH)2]. These calculational results lend credence to the notion that there is a W-Wbond of order 2.