Charge-compensated -carborane derivatives in the synthesis of iron(II) bis(dicarbollide) complexes.

A series of stable iron(II) bis(dicarbollide) derivatives [8,8'-(RNHC(Et)HN)-3,3'-Fe(1,2-CBH)] (R = Pr, R = Ph, (CH)OH, (CH)OH, (CH)NMe) was prepared starting from FeCl or [FeCl(dppe)] and the corresponding -carboranyl amidines [10-RNHC(Et)HN-7,8-CBH]. In a similar way, the reactions of the oxonium derivatives of -carborane with FeCl in tetrahydrofuran in the presence of -BuOK lead to the corresponding stable oxonium derivatives iron(II) bis(dicarbollide) [8,8'-(RR'O)-3,3'-Fe(1,2-CBH)] (RR' = (CH), (CH)O(CH), (CH); R = R' = Et), which can be alternatively prepared by the reaction of the parent iron(II) bis(dicarbollide) with tetrahydrofuran or 1,4-dioxane in the presence of MeSO. The cyclic voltammetry studies of the synthesized iron(II) bis(dicarbollide) derivatives revealed that the introduction of amidinium and oxonium substituents leads to a significant increase in the Fe/Fe redox potential relative to the parent iron(II) bis(dicarbollide).