The inverse sandwich complex [(K(18-crown-6))2Cp][CpFe(CO)2] – unpredictable redox reactions of [CpFe(CO)2]I with the silanides Na[SiRtBu2] (R = Me, tBu) and the isoelectronic phosphanyl borohydride K[PtBu2BH3]

Abstract

The dimeric iron carbonyl [CpFe(CO)₂]₂ and the iodosilanes tBu₂RSiI were obtained from the reaction of [CpFe(CO)₂]I with the silanides Na[SiRtBu₂] (R = Me, tBu) in THF. By the reactions of [CpFe(CO)₂]I and Na[SiRtBu₂] (R = Me, tBu) the disilanes tBu₂RSiSiRtBu₂ (R = Me, tBu) were additionally formed using more than one equivalent of the silanide. In this context it should be noted that reduction of [CpFe(CO)₂]₂ with Na[SitBu₃] gives the disilanes tBu₃SiSitBu₃ along with the sodium ferrate [(Na(18-crown-6))₂Cp][CpFe(CO)₂]. The potassium analogue [(K(18-crown-6))₂Cp][CpFe(CO)₂] (orthorhombic, space group Pmc2₁), however, could be isolated as a minor product from the reaction of [CpFe(CO)₂]I with [K(18-crown-6)][PtBu₂BH₃]. The reaction of [CpFe(CO)₂]₂ with the potassium benzophenone ketyl radical and subsequent treatment with 18-crown-6 yielded the ferrate [K(18-crown-6)][CpFe(CO)₂] in THF at room temperature. The crown ether complex [K(18-crown-6)][CpFe(CO)₂] was analyzed using X-ray crystallography (orthorhombic, space group Pna2₁) and its thermal behaviour was investigated.