title: Synthesis of well-defined bicapped octahedral iron clusters [((tren) L)2 Fe8 (PMe2 Ph)2 ](n) (n=0, -1).
abstract: The synthesis of polynuclear clusters with control over size and cluster geometry remains an unsolved challenge. Herein, we report the synthesis and characterization of open-shell octairon clusters supported by two heptaamine ligands [o-H2 NC6 H4 NH(CH2 )2 ]3 N ((tren) LH9 ). The crystal structure of the all-ferrous species ([(tren) L)2 Fe8 (PMe2 Ph)2 ] (1) displays a bicapped octahedral geometry with FeFe distances ranging from 2.4071(6) to 2.8236(5) Å, where the ligand amine units are formally in amine, amide, and imide oxidation states. Several redox states of the octairon cluster are accessible, as ascertained using cyclic voltammetry. The one-electron-reduced clusters [M](+) [((tren) L)2 Fe8 (PMe2 Ph)2 ](-) (M=Bu4 N (2 a); (15-crown-5)Na(thf) (2 b)) were isolated and characterized. Variable-temperature magnetic susceptibility data indicates that the exchange coupling within the [Fe8 ] core is antiferromagnetic which is attenuated upon reduction to the mixed valent anion.
authors: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA, 02138 USA.
authors: Raúl Hernández
authors: RH
authors: Sánchez
authors: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA, 02138 USA.
authors: Alexander M
authors: AM
authors: Willis
authors: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA, 02138 USA.
authors: Shao-Liang
authors: SL
authors: Zheng
authors: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St. Cambridge, MA, 02138 USA. betley@chemistry.harvard.edu.
authors: Theodore A
authors: TA
authors: Betley
mesh_terms: D000588:Amines / Q000138:chemical synthesis / Q000737:chemistry*; D043844:Crown Ethers / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D005296:Ferrous Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D059346:Magnets / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction
chemical_list: D000588:Amines; D043844:Crown Ethers; D005296:Ferrous Compounds; D008024:Ligands; C042148:15-crown-5
keywords: cluster compounds; cyclic voltammetry; iron; magnetic properties; structure elucidation