Our examination of the role of geometry optimization and spin projection on predicting Jcouplings used the test set constructed by Peralta and Rudra. This test set consists of nine medium-sized (40-100 atoms) binuclear transition metal complexes (Fig. ) that have spin-spin coupling between metals facilitated by bridging ligands. Specifically, the test set includes Cu(II), Cr(III), V(IV), Mn(II), Mn(III) and Mn(IV) metal centers and oxygen, nitrogen, and chlorine coordinating atoms. Experimentally, compounds 1-5 are observed to be AF while 6-9 are FM. Modifications were made to compounds 3, 6, 8 and 9 to ensure that the structures were in agreement with published structures or to remove unnecessary water molecules and ions that do not play a significant role in the transition metal complex structures (comparisons are provided in Table ).