Density functional theory (DFT) calculations have been used to investigate the effect of intermetallic electron transfer on the mode of magnetic coupling in the face-shared bimetallic complexes MWCl9n- (M = V, Cr, Mn; all with a nominal d(3) valence electronic configuration on each metal atom), These calculations illustrate a simple rule: when the oxidation state of M is lower than that of W, antiferromagnetic coupling is preferred, while ferromagnetism (via crossed exchange pathways) is favored when M has the higher oxidation state. This underlying trend in intermetallic interactions is seen to depend on the interplay among ligand field splitting, spin polarization splitting of alpha- and beta-spin orbitals, and the relative energies of the M and W valence d orbitals, and is mirrored in the results seen in a wider survey of mixed-metal, face-shared complexes.