Synthesis and structure of [EtV+•]5[Ag12(μ12-Ag){μ3-Fe(CO)4}8]·4 DMF: the missing [Ag13Fe8(CO)32]5– pentaanion as ethylviologen (EtV) salt

Abstract

Abstract The reaction in MeCN of [Ag5Fe4(CO)16]3– in its Na+ salt with EtV2+ 2I– leads to precipitation of [EtV+•]5[Ag13Fe8(CO)32]. Its DMF solution is deep-green, displays infrared carbonyl absorptions very similar to those of the paramagnetic [Ag13Fe8(CO)32]4– tetraanion and only shows the EPR signal of the EtV+• radical cation. The colour of the solution and the IR spectrum suggest the presence of a charge–transfer salt. Crystallisation of the precipitate from DMF and isopropyl alcohol affords brown crystals of [EtV+•]5[Ag13Fe8(CO)32]·4 DMF, which are insoluble in all organic solvents, DMF included. X-ray analysis of the crystals provided the structure of the yet uncharacterised [Ag13Fe8(CO)32]5– pentaanion and allowed the first determination of the structure of the ethylviologen radical cation. The latter gives rise to stacks in which weakly-bound pentameric moieties are clearly identifiable. The structural findings are implemented by spectroscopic measurements and EHMO calculations. To cite this article: D. Collini et al., C. R. Chimie 8 (2005).