Synthesis and full characterization
of cationic isostructural “sandwich”
diimine-coinage metal ethylene complexes are reported. Ethylene self-exchange
kinetics proceeds by an associative exchange mechanism for Cu and
Au complexes. The fastest ligand exchange was observed for Ag complex <b>8a</b>. The upper limit of Δ<i>G</i><sup>⧧</sup>, assuming associative ligand exchange, was found to be ca. 5.0 kcal/mol.
Ethylene self-exchange in
Cu complex <b>7b</b> proceeds with Δ<i>G</i><sub>298</sub><sup>⧧</sup> = 12.9 ± 0.1 kcal/mol, while
the exchange is the slowest in Au complex <b>9</b>, with Δ<i>G</i><sub>298</sub><sup>⧧</sup> = 16.7 ± 0.1 kcal/mol.
Copper complex <b>7b</b> is unusually stable and can survive
in air for years
