There's a field known as 'mathematical chemistry', they even have a
http://www.springerlink.com/content/101749/". But there are few groups or departments dedicated to the subject, and few who would label themselves a 'mathematical chemist' or similar.
What you have, is the mathematically-intensive areas of chemistry, which are: Physical chemistry, chemical physics, theoretical chemistry, computational chemistry in general and quantum chemistry in particular. (These aren't very distinct fields) In general, the more mathematical areas are also more physical, and so you have to learn physics, which doesn't necessarily mean you have to be a physicist. These fields have people from both backgrounds. So if you want to go into these areas, you should study math, physics, phys-chem etc.
As for research, grad school is more or less obligatory in any scientific field, there's no getting around that, really. Which doesn't mean you can't contribute at all; many universities have programs where undergrads get to assist in research. If yours doesn't, you could take the initiative and simply ask if they have some suitable small thing you could do as a project. Although the main problem isn't really finding a task - a good researcher should have more ideas than he has time. The main problem is whether they'd have to spend more time supervising/tutoring than it would've taken them to solve it themselves. (OTOH, that could possibly be delegated to a grad student)