  Magnetization, AC susceptibility and $\mu$SR measurements have been performed
in neutral phthalocyaninato lanthanide ([LnPc$_2]^0$) single molecule magnets
in order to determine the low-energy levels structure and to compare the
low-frequency spin excitations probed by means of macroscopic techniques, such
as AC susceptibility, with the ones explored by means of techniques of
microscopic character, such as $\mu$SR. Both techniques show a high temperature
thermally activated regime for the spin dynamics and a low temperature
tunneling one. While in the activated regime the correlation times for the spin
fluctuations estimated by AC susceptibility and $\mu$SR basically agree, clear
discrepancies are found in the tunneling regime. In particular, $\mu$SR probes
a faster dynamics with respect to AC susceptibility. It is argued that the
tunneling dynamics probed by $\mu$SR involves fluctuations which do not yield a
net change in the macroscopic magnetization probed by AC susceptibiliy. Finally
resistivity measurements in [TbPc$_2]^0$ crystals show a high temperature
nearly metallic behaviour and a low temperature activated behaviour.
