Synthesis, Molecular Structures, and Reactivity of Dianionic Guanidinate Lanthanide/Lithium Derivatives

Anhydrous LnCl 3 was treated with [Li i PrNC(HN i Pr)N(C 6 H 4 p ‐Cl)] and n BuLi at a molar ratio of 1:2:2 in THF to afford heterometallic Ln–Li chlorides stabilized by two dianionic guanidinate ligands [{( i PrN) 2 C[NLi(THF) 3 (C 6 H 4 p ‐Cl)]} 2 Ln(μ‐Cl 2 )Li(THF) 2 ] · n THF [Ln = La ( 1 ), Nd ( 2 ) n = 2; Sm ( 3 ), Yb ( 4 ), Y ( 5 ) n = 3] in good yields. Treatment of thechlorides with NaO i Pr and KO t Bu yielded the corresponding isopropoxides [{[( i PrN) 2 CN(C 6 H 4 p ‐Cl)Li] 2 (DME)(LiCl)Ln(O i Pr) 2 } 2 ] 2– [{Li(DME) 3 } + ] 2 · 3C 6 H 14 [Ln = Nd ( 6 ), Sm ( 7 ), Yb ( 8 ), Y ( 9 ); DME = 1,2‐dimethoxyethane] and tert ‐butoxides [{( i PrN) 2 C(NC 6 H 4 p ‐Cl)Li(DME)(LiCl)} 2 Ln(O t Bu) 2 ] – [Li(DME) 3 ] + · 0.5C 6 H 14 [Ln = Nd ( 10 ), Yb ( 11 )]. Attempts to synthesize the corresponding amide and guanidinate complexes by treating 2 with LiNHC 6 H 5 and [Li i PrNC(HN i Pr)N(C 6 H 5 )] led to the isolation of guanidinate lithium,[Li i PrNC(HN i Pr)N(C 6 H 4 p ‐Cl)(THF)] 2 ( 12 ). Addition of diisopropylcarbodiimide ( i PrN=C=N i Pr) into the reaction system of trisguanidinate lanthanide complex [{ i PrNHC(N i Pr)(NC 6 H 4 p ‐Cl)} 3 Yb(THF)] and n BuLi led to the preparation of the first heterometallic Yb–Li complex with a novel biguanidinate ligand [{ i PrNHC(N i Pr)N(C 6 H 4 p ‐Cl)} 2 Yb{( i PrNC(N i Pr) 2 )N(C 6 H 4 p ‐Cl)C( i PrN)}Li(THF)] · THF ( 13 ). The molecular structures of 1 – 3 and 6 – 13 were determined by X‐ray crystal structural analysis.