Synthesis of Well‐Defined Bicapped Octahedral Iron Clusters [(^trenL)₂Fe₈(PMe₂Ph)₂]ⁿ (n=0, −1)

Abstract

The synthesis of polynuclear clusters with control over sizeand cluster geometry remains an unsolved challenge. Herein, we report the synthesis and characterization of openshell octairon clusters supported by two heptaamine ligands [o-H 2 NC 6 H 4 NH(CH 2 ) 2 ] 3 N( tren LH 9 ). The crystal structure of the all-ferrous species ([ tren L) 2 Fe 8 (PMe 2 Ph) 2 ]( 1)d isplays abicapped octahedral geometry with Fe À Fe distances ranging from 2.4071 (6) to 2.8236(5) , where the ligand amine units are formally in amine,a mide,a nd imide oxidation states. Several redox states of the octairon cluster are accessible,a s ascertained using cyclic voltammetry.T he one-electron-reduced clusters [M] + [( tren L) 2 Fe 8 (PMe 2 Ph) 2 ] À (M = Bu 4 N( 2a);(15-crown-5)Na(thf) (2b)) were isolated and characterized. Variable-temperature magnetic susceptibility data indicates that the exchange coupling within the [Fe 8 ]c ore is antiferromagnetic which is attenuated upon reduction to the mixed valent anion.Scheme 1. Synthesis of [( tren L) 2 Fe 8 (PMe 2 Ph) 2 ]a nd its anion. Py =pyridine.

Selective Synthesis of Site-Differentiated Fe4S4 and Fe6S6 Clusters

“…the identity of the Fe precursor and the presence or absence of additional phosphine ligands) 36,37 and that 8-Fe clusters could be accommodated by expanding the size of the ligand cavity and introducing an additional amine donor. 38 In addition, reactive trimetallic clusters have been prepared using a rigid tris(diketiminate) scaffold developed by Murray et al [39][40][41][42] and Agapie et al have employed a 1,3,5-triarylbenzene substituted with three dipyridyl alkoxide groups as a framework to selectively construct, for example, Mn3O4M (M = Ca 2+ , Ln 3+ , etc.) cubanes as models for the oxygen-evolving complex in photosystem II.…”