Thermo- and photo-induced electron transfer in a series of [Fe2Co2] capsules

Recently, a family of [Fe2Co2] molecular capsules that display tunable electron transfer-coupled spin transition (ETCST) behavior were reported via a smart approach through Schiff-base condensation of aldehyde-functionalized 2,2-bipyridines (bpy(CHO)) and 1,7-heptanediamine (H2N(CH2)(7)NH2). Here, three more capsule complexes {[(Tp(R))Fe(CN)(3)](2)[Co(bpy(C=N(CH2)nN=C)bpy)](2)[ClO4](2)center dot n(solvent) (1, Tp(R) = Tp*, n = 5, sol = 8DMF; 2, Tp(R) = Tp(Me), n = 9, sol = 5MeCN; and 3, Tp(R) = Tp*, n = 11, sol = 5MeCN), where Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate and Tp(Me) = hydridotris(3-methylpyrazol-1-yl)borate are reported, demonstrating a successful extension of such an approach with other alkyldiamines of different lengths. Combined X-ray crystallographic, infrared spectroscopic and magnetic studies reveal incomplete electron transfer with either changing temperature or upon light exposure.