Thorium(IV) alkyl synthesis from a thorium(III) cyclopentadienyl complex and an N-heterocyclic olefin

Abstract

Treatment of the tris(cyclopentadienyl) thorium(III) complex [Th(η5-Cp′′)3] [1, Cp′′ = C5H3-1,3-(SiMe3)2] with the N-heterocyclic olefin H2C=C(NMeCH)2 (2) reproducibly produces the thorium(IV)-methyl derivative [Th(η5-Cp′′)3(Me)] (3) along with MeImCH2CH2ImMe (Im = imidazole). The reaction mechanism, which is consistent with 1H NMR spectroscopic observations, is proposed to proceed via: (i) coordination of 2 to 1; (ii) one-electron transfer from thorium to 2; (iii) N-methyl cleavage and transfer to thorium to give 3; (iv) coupling of the resulting imidazolium radical by-product to give MeImCH2CH2ImMe. Complex 3 has been characterised by single crystal X-ray diffraction, multi-nuclear NMR and IR spectroscopies, and elemental analyses, and MeImCH2CH2ImMe by 1H NMR spectroscopy and mass spectrometry.