Half-Sandwich Alkyl, Amido, and Iodo Samarium(II) Complexes: Non-Conventional Sterically Governed Oxidation of (tBu4 Carb)2 Sm.

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. SmII . 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 SmII 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.