Contrasting Reactions of Carbodiimides with Divalent Lanthanoid Species

Abstract Reactions of lanthanoid species with carbodiimides (RN ═ C ═ NR′) show considerable variety. Thus, treatment of the divalent 2,6‐di‐ tert ‐butyl‐4‐ethylphenolatosamarium complex, [Sm(OAr Et ) 2 (thf) 3 ]·PhMe with N , N '‐diisopropylcarbodiimide ( i PrNCN i Pr) resulted in the formation of the oxalamidinatosamarium(III) complex [(OArEt)₂Sm(μ‐C₂N₄ i Pr₄)Sm(OAr Et )₂]·2PhMe (1). In contrast, the use of the bulkier N , N' ‐dicyclohexylcarbodiimide (CyNCNCy) led to the formation of a formamidinatosamarium(III) complex [Sm(OAr Et ) 2 (CyNC(H)NCy)(thf) 2 ]⋅2thf (2) . Reactions between rare earth metals (RE = Yb, Eu) with one molar equivalent of bis(phenylethynyl)mercury (Hg(PhCC) 2 ) and two molar equivalents of N , N '‐dicyclohexylcarbodiimide (CyNCNCy) in tetrahydrofuran (thf) at room temperature yielded lanthanoid C ‐phenylethynylamidinate complexes, trivalent [Yb III {CyNC(C≡CPh)NCy} 3 ]·2thf (3) and divalent [Eu{CyNC(C≡CPh)NCy}₂(thf)₂] (4) . [Sm(OAr Et ) 2 (thf) 3 ].PhMe was obtained from SmI 2 (thf) 2 and the in situ generated potassium aryl oxide and is a five‐coordinate monomer with a stereochemistry between trigonal bipyramidal and square pyramidal.