If impatiens won't do it, nothing will....perhaps a peace lily? house plant...spath....something..I forget.
It does well in very deep shade.
Linda C

Aspidistra (Cast Iron Plant) is another foliage plant that is often used in locations where nothing else will thrive. I agree with Linda, if this location is THAT dark, then you need to consider filling the space with foliage, rather than expecting something to flower.

You're sure, by the way, that the problem with the impatiens is the lack of light, and not something else? Poor drainage, over watering, over fertilization, icky potting soil.....the usual list of problem causing factors.