@SF.'s question What are the parameters of the new Iodine electrical rocket engine developed by RSC Energia? links to the short RT article 'Ten times cheaper': Russian space company testing iodine rocket engine which contains a sentence which was likely altered during translation as well as in paraphrasing for a non-space general news publication:
Furthermore, xenon-run engines are incapable of long-distance flights, like going to the Moon.
But my question is only about the orbital mechanics of going to lunar orbit from LEO using a low-thrust form of propulsion such as ions.
From LEO you can take your time slowly spiraling outwards in Earth's gravity well as shown here and is done by some of the newer "all electric propulsion" communications satellites that use ion propulsion to get to GEO.
And if you enter a high lunar orbit, you may be able to lower it using ion propulsion as well, provided it can handle the lumpy gravity and perturbations from the Earth and Sun.
But my question is about the transfer between Earth-bound to Moon-bound orbits. I'm wondering if you can make the transfer with very low propulsion at all times, or if there is some point where a high impulse would be needed in this four-body problem to change from one to the other without risk of getting lost or thrown into a heliocentric orbit.
For "how low is low thrust?" you could choose an existing spacecraft like an all-electric-to-GEO communications satellite, or a deep-space explorer like DAWN.
Sound mathematical arguments would be great, or a reference to a published study with conclusive results would be good as well. Even if possible, I'd still like to understand if it was tricky to make it work, or if it is actually not as hard as I might imagine.