Temperature dependencies of the H-1 NMR spectra of asymmetric double-decker
complexes of DyH(oep)(tpp) (I) and LuH(oep)(tpp) (II), where tpp is tetrap
henylporphyrin and oep is octaethylporphyrin, have been analyzed. The kinet
ic and thermodynamic parameters for intramolecular phenyl ring rotations ha
ve been determined. The rotation in (I) is characterized by k(298 K) = 11.4
s(-1), DeltaH(double dagger): = 48.0+/-6.0 kJ mol(-1) while in (II) the de
rived parameters are found to bek(298K) = 14.0 s(-1) DeltaH(double dagger)
= 65.5+/-7.1 kJ mol(-1). The possible reasons for the different characteris
tics of these complexes are discussed. The structural parameters calculated
for I and YbH(oep)(tpp) (III), indicate close similarities between the com
plexes. Nevertheless, it appears that the principal values of the molar par
amagnetic susceptibility tensor (Xi) differ significantly in these complexe
s.