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

Abstract

AbstractAnhydrous LnCl3 was treated with [LiiPrNC(HNiPr)N(C6H4p‐Cl)] and nBuLi at a molar ratio of 1:2:2 in THF to afford heterometallic Ln–Li chlorides stabilized by two dianionic guanidinate ligands [{(iPrN)2C[NLi(THF)3(C6H4p‐Cl)]}2Ln(μ‐Cl2)Li(THF)2]·nTHF [Ln = La (1), Nd (2) n = 2; Sm (3), Yb (4), Y (5) n = 3] in good yields. Treatment of thechlorides with NaOiPr and KOtBu yielded the corresponding isopropoxides [{[(iPrN)2CN(C6H4p‐Cl)Li]2(DME)(LiCl)Ln(OiPr)2}2]2–[{Li(DME)3}+]2·3C6H14 [Ln = Nd (6), Sm (7), Yb (8), Y (9); DME = 1,2‐dimethoxyethane] and tert‐butoxides [{(iPrN)2C(NC6H4p‐Cl)Li(DME)(LiCl)}2Ln(OtBu)2]–[Li(DME)3]+·0.5C6H14 [Ln = Nd (10), Yb (11)]. Attempts to synthesize the corresponding amide and guanidinate complexes by treating 2 with LiNHC6H5 and [LiiPrNC(HNiPr)N(C6H5)] led to the isolation of guanidinate lithium,[LiiPrNC(HNiPr)N(C6H4p‐Cl)(THF)]2 (12). Addition of diisopropylcarbodiimide (iPrN=C=NiPr) into the reaction system of trisguanidinate lanthanide complex [{iPrNHC(NiPr)(NC6H4p‐Cl)}3Yb(THF)] and nBuLi led to the preparation of the first heterometallic Yb–Li complex with a novel biguanidinate ligand [{iPrNHC(NiPr)N(C6H4p‐Cl)}2Yb{(iPrNC(NiPr)2)N(C6H4p‐Cl)C(iPrN)}Li(THF)]·THF (13). The molecular structures of 1–3 and 6–13 were determined by X‐ray crystal structural analysis.