Q.Do you think that lanthanoid complexes would show magnetism?

Lanthanoid ions' magnetic moments are governed by their number of unpaired 4f electrons, tabulated (with observed effective moments in Bohr Magnetons) from La3+ (4f0, 0 unpaired, diamagnetic) through Gd3+ (4f7, 7 unpaired, the maximum in the series, 7.9-8.0 BM observed) to Lu3+ (4f14, 0 unpaired, diamagnetic again). Unlike first-row transition-metal ions, however, orbital angular momentum is SIGNIFICANT (not quenched) for lanthanoid ions, so the simple spin-only formula mu = sqrt(n(n+2)) used for 3d ions is not reliable here -- more complete equations accounting for total angular momentum are needed, and the observed moments are also temperature-dependent. Only ions with a completely empty (f0, e.g. La3+) or completely full (f14, e.g. Lu3+) f subshell are genuinely diamagnetic; every other lanthanoid ion (f1 through f13) has at least one unpaired electron and is paramagnetic, which is why a set of ions is 'all paramagnetic' only if none of its members happens to be f0 or f14.