Lithium complexes supported by tripodal diaminebis(aryloxido) ligands: Synthesis and structure

Abstract

The diaminebis(aryloxido) ligand precursors H₂L¹ and H₂L² [H₂L¹ = Me₂NCH₂CH₂N(CH₂-4-CMe₂CH₂CMe₃-C₆H₃OH)₂; H₂L² = Me₂NCH₂CH₂N(CH₂-4-Me-C₆H₃OH)₂] were synthesized by a straightforward single-step Mannich condensation. Their reactions with 2 molar equivalents of MeLi in thf afforded [Li₄(μ-L-κ⁴O,N,N,O)₂(thf)₂] (1a, L¹; 1b, L²) and unexpectedly small amounts (∼9%) of [Li₆(μ-L-κ⁴O,N,N,O)₂(μ³-Cl)₂(thf)₄]·thf (2a·thf; L¹; 2b·thf, L²). Stoichiometric reactions of LiCl, MeLi and ligand precursors H₂L led to the formation of 2a and 2b in high yield (∼80%). All compounds were characterized by chemical and physical techniques including X-ray crystallography for H₂L¹, H₂L², 1b, 2a and 2b.