Cross sections for intermultiplet transitions in Li(2p²P)-He(1¹S) collisions are calculated for impact energies E between 6*10^-5 eV and 6*10^-2 eV by a close-coupled wave treatment. A special study is made of the onset of spin uncoupling as E is increased. The total cross sections indicate that the spin-uncoupled limit (in which the spin of the valence electron is unaffected by the collision) is reached at 3*10^-4 eV. However partial-wave analysis indicates that there are significant departures from the limit up to 3*10^-3 eV. A correlation between peaks in the calculated cross sections and resonances in elastic scattering by the ² Pi molecular potential is studied, and is interpreted as showing the essentially molecular nature of the collision.