Octanuclear heterometallic FeIII-CeIV pivalate clusters: From a close {Fe4Ce4(μ4-O)4} cage to an open {Fe4Ce4(μ4-O)2(μ3-O)2} core

Ultrasonic irradiation of trinuclear [Fe3O(O2CCMe3)6(H2O)3]Me3CCO2·2(Me3CCO2H) or hexanuclear [Fe6O2(OH)2(O2CCMe3)12] pivalate precursors with Ce(NO3)6·6H2O, NaN3 and triethanolamine (H3tea) in MeOH/MeCN solution results in the synthesis of two new octanuclear FeIII-CeIV clusters formulated as [Fe4Ce4O4(O2CCMe3)4(tea)4(N3)4(MeOH)4]∙MeOH (1) and [Fe4Ce4O4(O2CCMe3)6(tea)4(N3)2(MeOH)2]∙3(MeOH) (2). The spectroscopic and thermal properties of these compounds corroborate oxidation states and formula. Single crystal X-ray diffraction analysis revealed that the metal atoms in clusters 1 and 2 are organized in unprecedented close {Fe4Ce4(μ4-O)4} and open {Fe4Ce4(μ4-O)2(μ3-O)2} cores, respectively. The topology of these cores has not been observed before in FeIII-CeIV chemistry.