The chemistry of cycloheptatrienyl complexes of molybdenum and tungsten: the synthesis and reactions of some vinylidene and alkynyl derivatives
- 1 January 1987
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 12,p. 3049-3053
- https://doi.org/10.1039/dt9870003049
Abstract
Reaction of the terminal alkyne HCCPh with [Mo(sol)(dppe)(η-C7H7)][PF6][(2a), sol = NCMe; (2b), sol = acetone; dppe = Ph2PCH2CH2PPh2] in refluxing acetone yields the phenylvinylidene complex [Mo(CCHPh)(dppe)(η-C7H7)][PF6](3) which is readily deprotonated to give the alkynyl complex [Mo(CCPh)(dppe)(η-C7H7)](4). A similar reaction sequence-starting from HCCBut and (2b) yields [Mo(CCBut)(dppe)(η-C7H7)](6). Protonation of (4) with H[BF4]·Et2O reforms [Mo(CCHPh)(dppe)(η-C7H7)]+. Electrochemical studies show that (4) and (6) undergo a reversible one-electron oxidation at a glassy carbon electrode in CH2Cl2 and chemical oxidation with [Fe(η-C5H5)2][BF4] yields the radical cations [Mo(CCR)(dppe)(η-C7H7)][BF4][(5), R = Ph; (7), R = But] which have been studied by e.s.r. spectroscopy. Reaction of LiCCPh with [MX(CO)2(η-C7H7)](M = Mo or W; X = I or Cl) affords the parent dicarbonylalkynyl complexes [M(CCPh)(CO)2(η-C7H7)][(8), M = Mo; (9), M = W].Keywords
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