| Abstract
| - The complexes (C5Me5)2Yb(RNC(R‘)C(R‘)NR) are paramagnetic, and their net magnetic moments show that the spins on YbIII(4f13) and the radical anion (S = 1/2) are correlated, as previously observed in (C5Me5)2Yb(bipy).
- The paramagnetic 1:1 coordination complexes of (C5Me5)2Yb with a series of diazabutadiene ligands,RNC(R‘)C(R‘)NR, where R = CMe3, CHMe2, adamantyl, p-tolyl, p-anisyl, mesityl when R‘ = Hand R = p-anisyl when R‘ = Me, have been prepared. The complexes are paramagnetic, but their magneticmoments are less than expected for the two uncoupled spin carriers, (C5Me5)2YbIII(4f13) and thediazabutadiene radical anions (S = 1/2), which implies exchange coupling between the spins. The variable-temperature 1H NMR spectra show that rotation about the R−N bond is hindered and these barriers areestimated. The barriers are largely determined by steric effects, but electronic effects are not unimportant.
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