A One-Dimensional Coordination Polymer Assembled from a Macrocyclic Mn(III) Single-Molecule Magnet and Terephthalate

Herein the strategy of deliberate assembly of stable soluble macrocyclic single-molecule magnets (SMMs), using appropriately chosen linkers to bridge the axial sites, as a controlled way of forming single-chain magnets (SCMs) is tested. First, the manganese(III) macrocyclic complex, [Mn-III(L-Pr)(NCS)(2)] (1), of the monoanionic tetradentate equatorial-N4-donor macrocyclic (L-Pr)(-) ligand (formed from [1 + 1] Schiff base condensation of 2,2'-iminobisbenzaldehyde and dipropylenetriamine) is shown to be an SMM. Then, the 1:1 reaction of SMM 1 with sodium terephthalate linkers in H2O/DMF is shown, by X-ray structure determination, to form dark red single crystals of the desired one-dimensional (ID) coordination polymer, [Mn-III(L-Pr)(tpa)](n)center dot nH(2)O center dot 0.5nDMF (2), of alternating dicationic macrocycles [Mn-III(L-Pr)](2+) (from 1) linked by the bridging dianionic linkers [tpa](2-). Despite having the desired structural features, magnetic measurements show that 2 is an SMM, not an SCM, as the coupling along the ID coordination polymer is negligible (with Delta(eff)/k(B) = 13.7(5) K and tau(0) = 1.4(5) x 10(-7) s). Future attempts to use this strategy of linking macrocyclic SMMs together to access SCMs will clearly require the use of linkers that are able to more efficiently relay the magnetic information along the resulting chain.