Polymetallic clusters of iron(III) with derivatised salicylaldoximes

The synthesis and magnetic properties of the compounds [HNEt 3][Fe2(OMe)(Ph-sao)2 (Ph-saoH)2]·5MeOH (1·5MeOH), [Fe3O(Et-sao)(O2CPh)5(MeOH)2]·3MeOH (2·3MeOH), [Fe4(Me-sao)4(Me-saoH)4] (3), [HNEt3]2[Fe6O2(Me-sao)4(SO4)2(OMe)4(MeOH)2] (4), [Fe8O3(Me-sao)3(tea)(teaH)3(O2CMe)3] (5), [Fe8O3(Et-sao)3(tea)(teaH)3(O2CMe)3] (6), and [Fe8O3(Ph-sao)3(tea)(teaH)3(O2CMe)3] (7) are reported (Me-saoH2 is 2-hydroxyacetophenone oxime, Et-saoH2 is 2-hydroxypropiophenone oxime and Ph-saoH2 is 2-hydroxybenzophenone oxime). 1–7 are the first FeIII compounds synthesised using the derivatised salicylaldoxime ligands, R-saoH2. 1 is prepared by treatment of Fe2(SO4)3·6H2O with Ph-saoH2 in the presence of NEt3 in MeOH; 2 prepared by treatment of Fe(ClO4)2·6H2O with Et-saoH2 and NaO2CPh in the presence of NEt4OH in MeOH; 3 prepared by treatment of Fe(ClO4)2·6H2O with Me-saoH2 and NaO2CCMe3 in the presence of NEt4OH in MeOH; and 4 prepared by treatment of Fe2(SO4)3·6H2O withMe-saoH2 in the presence of NEt3 in MeOH. 4 is a rare example of a polynuclear iron complex containing a coordinated SO42− ion. Compounds 5–7 are prepared by treatment of Fe(O2CMe)2 with Me-saoH2 (5), Et-saoH2 (6), Ph-saoH2 (7) in the presence of H3tea (triethanolamine) in MeOH, and represent the largest nuclearity FeIII clusters containing salicyladoxime-based ligands, joining a surprisingly small family of characterised octanuclear Fe complexes. Variable temperature magnetic susceptibilty measurements of 1,3 and 5–7 reveal all five complexes possess S = 0 spin ground states; 2 possesses an S = 1/2 spin ground state, while 4 has an S = 4 ± 1 spin ground state. Introduction