Half‐Sandwich Alkyl, Amido, and Iodo Samarium(II) Complexes: Non‐Conventional Sterically Governed Oxidation of (<i>t</i>Bu₄Carb)₂Sm

Abstract

The half-sandwich tetra-tert-butylcarbazol-9-yl iodo complex [(tBu₄ Carb)Sm(μ-I)(THF)₂ ]₂ (1) was synthesized by the salt metathesis reaction of tBu₄ CarbK and SmI₂ (THF)₂ in THF. Complex 1 along with metallic Cu was also isolated from the oxidation reaction of (tBu₄ Carb)₂ Sm by CuI. The formation of stable radical tBu₄ Carb^. was detected in this non-conventional process, indicating preferential oxidation of anion tBu₄ Carb^- vs. Sm^II . The treatment of 1 with two equivalents of dibenzo-18-crown-6 resulted in heterolytic dissociation of a η⁵ -bond Sm-tBu₄ Carb and afforded an ionic compound [tBu₄ carb^- ][SmI(crown)(THF)₂ ]⁺ (4). Alkylation of 1 with o-NMe₂ C₆ H₄ CH₂ K (1:2 molar ratio) in THF allowed for the synthesis of half-sandwich Sm^II alkyl complex (tBu₄ Carb)SmCH₂ (o-NMe₂ C₆ H₄ CH₂ )(THF)₂ (5) in 55 % yield. The amido complex (tBu₄ Carb)SmN(SiMe₃ )₂ (DME) (6) was obtained by the reaction of 1 with two molar equivalents of NaN(SiMe₃ )₂ in THF in 89 % yield.