It might seem, at first, that Group Sales and Corporate Sponsorship are worlds away from each other. However, they can work together to sell tickets AND get donations.
Perhaps the easiest way to start is to institute a Corporate Discount Program offering ticket discounts to a few of the large businesses in the area. A good way to go about this is to get together with the staff member(s) who are in charge of sponsorships and inquire about the biggest donor businesses but ALSO the businesses that they have as prospects.
Most likely, the business will offer a discount to their employees more readily than contribute funds. The more employees that take advantage of the discount will show the head honchos that your organization is something that the employees care about and they should become a sponsor.
This approach requires that the Group Sales and Corporate Sponsoship staff work together as a team and share information. The typical guarded nature that both parties have about contacts must be shed to get the most out of the effort.