EPR evidence for a new, important limiting resonance structure in the explanation of the bonding of spin-crossover Fe(III) dichalcogenocarbamates

Iron(III) Spin Crossover Compounds

“…In contrast to the extensive literature on Fe(III) dithiocarbamates (Sect. 2.1) and to a lesser extent Fe(III) diselenocarbamates [62,65,[67][68][69][70][71][72][73], the Fe(III) thioselenocarbamates [68][69][70][71][72][73] have not been widely studied. Certainly, one reason for this is the difficult preparation of the reagent carbon sulfideselenide (CSSe) [74].…”

“…Certainly, one reason for this is the difficult preparation of the reagent carbon sulfideselenide (CSSe) [74]. This was later circumvented by an improved synthetic method for CSSe [75], allowing Dietzsch et al [68][69][70][71][72][73] to report a large range of Fe(III) thioselenocarbamates. Although these studies have been carried out with care, the authors did not address the possibility of formation of different geometric isomers associated with the asymmetric na-ture of the bidentate ligand.…”

“…The same authors later used information obtained from EPR spectra to propose a new resonance structure for the bonding of spin crossover Fe(III) dichalcogencarbamates. This low spin structure would involve an unpaired electron on the nitrogen atom of the dichalcogencarbamate and the transfer of an electron from the nitrogen to the Fe(III) ion [73]. Unfortunately, X-ray structures have not been reported for these selenium derivatives.…”

Super reduced Fe4S4 cluster of Balch's dithiolene series

“…A super hyperfine interaction based on the low abundance of the naturally occurring 13 C nuclei in the paramagnetic ion, Mo(CN) 8 ] 3− is known. [21][22][23] Reaction of complex 1 with acids…”