Your problem is not in van der Waals contacts. The first problem is that SCF (i.e., electronic problem, not nuclear) does not converge. I suggest that you divide you system into three parts: two cation-bromide pairs and the rhenium-containing center. Perform SCF for each part separately and see, which part is problematic.
Are you sure that the rhenium-containing complex is singlet?
Geometry optimization (nuclear problem) can be done only with converged SCF. You will not be able to do this until SCF is converged. Van der Waals contacts pertain to the nuclear part of you problem. Forget them until we get through with SCF.