Abstract
Terpyridine-based cobalt(II) complex, [Co(II)(HL)(2)] (1; H(2)L = 2,2':6',2″-terpyridine-5,5″-diyl dicarboxylic acid), forms a hydrogen-bonded diamond framework with solvent absorption and desorption capabilities. The desolvated form (1·desolv) exhibits spin transition (ST) behavior accompanied by thermal hysteresis. To investigate the effect of metal-dilution, an Fe(2+) center, which has a low-spin state (S = 0) and coordinates to two terpyridine moieties, was introduced. The resulting complexes, [Co(II) (x) Fe(II) (1-x) (HL)(2)], where x = 0.88 (2), 0.55 (3), and 0 (4), demonstrated a significant influence of metal-dilution on the desolvated forms, but not on the solvated forms. Namely, the spin state is more strongly affected by the presence of solvent than by metal-dilution. However, in the absence of solvent, the Fe(2+) ratio significantly impacts the ST behavior.