Molecular spin frustration in mixed-chelate Fe5 and Fe6 oxo clusters with high ground state spin values

Mixed-chelate FeIII clusters from picolinic acid (picH) and triethanolamine (teaH3) [Fe6O2(OH)2(O2CMe)4(pic)4(teaH)2] (1) and [Fe5O2(O2CBut)4(pic)3(teaH)2] (3) are described. Magnetic data, DFT calculations, and a magnetostructural correlation have allowed rationalization of their S = 5 and S = 5/2 ground states, respectively, and assisted fits of χMT vs T data to obtain Jij values.