One dimensional assembly of Mn-6 single molecule magnets linked by oligothiophene bridges

A new 1D coordination polymer comprised of [(Mn6O2)-O-III(Et-sao)(6)(EtOH)(4)(H2O)(2)](2+) units and bithiophene dicarboxylato was synthesized by mixing EtsaoH(2) (salicylaldoxime), H(2)btda (2,2'-bithiophene- 5,5'-dicarboxylic acid) and Mn(ClO4)(2)center dot 6H(2)O in the presence of NEt4OH. The crystal structure was determined and consists of Mn-6 clusters bridged by the bithiophene dicarboxylato ligands coordinated to two of the Mn-III ions of the Mn-6 polynuclear complex. Direct current magnetic measurements show an overall ferromagnetic interaction between the Mn-III ions within the Mn-6 cluster leading to an S = 12 ground state for the Mn-6 unit. Furthermore, this compound presents single-molecule magnet behaviour. Slow relaxation of the magnetization is observed at low temperature following a thermal activated regime with U-eff approximate to 50 K and tau(0) approximate to 2.2 10(-10) s. The magnetic measurements do not show any noticeable interaction between the Mn-6 clusters through the bithiophene dicarboxylato bridges.