Synthesis, Characterization, and Olefin/CO Exchange Reactions of Copper(I) Derivatives Containing Bidentate Oxygen Ligands

New hexafluoroacetylacetonate (hfacac) and trifluoroacetato olefin complexes of copper(I)
of the general formulas Cu(hfacac)(olefin) and Cu(CF3COO)(olefin) have been prepared from
Cu2O/hfacacH/olefin or Cu(CF3COO)(toluene)0.5/olefin systems. The structures of [Cu(hfacac)(coe)], [Cu(hfacac)(van)], [Cu(μ-CF3COO)(tbve)]n, and [Cu(μ-CF3COO)(van)]2·C7H8 have been
determined by X-ray diffraction methods, where coe = cyclooctene, van = 4-vinylanisole,
and tbve = tert-butyl vinyl ether. In the solid state, the 4-vinylanisole/trifluoroacetate complex
[Cu(CF3COO)(van)]2 is dimeric with two carboxylato groups symmetrically bridging two
copper atoms, while the tert-butyl vinyl ether derivative [Cu(μ-CF3COO)(tbve)]n is polymeric
with single [CF3COO]- bridges between adjacent copper atoms. Olefin hfacac complexes are
monomeric, and considering the two oxygen atoms and the midpoint of the double bond of
the coordinated olefin, the copper atom lies in a nearly trigonal-planar environment. The
carbonylation reactions of Cu(CF3COO)(olefin), (olefin = tbve, van; 2Cu(CF3COO)(olefin) +
2CO ⇆ [Cu(CF3COO)(CO)]2 + 2(olefin)) and of Cu(hfacac)(olefin) (olefin = coe, 1,5-cyclooctadiene (cod), norbornene (nbe), van; Cu(hfacac)(olefin) + CO ⇆ Cu(hfacac)(CO) +
olefin) have been studied gas volumetrically, and the equilibrium constants for the
displacement of the coordinated olefin by carbon monoxide have been determined at different
temperatures. Some hypotheses on the copper−olefin bond have been formulated on the
basis of structural, thermodynamic and spectroscopic (13C NMR) data.