Multidentate Aminoalkoxides. Synthesis and Complexation Behavior to Lithium and Sodium

Abstract

Abstract The tris(dimethylaminomethyl)-substituted alcohol (R2NCH2)3COH (R = Me: 1) was synthesized by reaction of 1-chloro-2,3-epoxy-2-chloromethylpropane with a large excess of 40% aqueous HNMe2 in 95% yield as colorless liquid (b.p. 87 ­­°C/1 mbar). Similar syntheses led to the respective amino alcohols with R = Et, CH2Ph. The dimethylamino alcohol 1 was characterized crystallographically as hydrochloride salt 2. Reaction of 1 with elemental sodium in toluene gave the tetrameric alcoholate [(Me2NCH2)3CONa]4 (3) which has a heterocubane structure in the solid state. In addition to three oxygen atoms, each sodium atom is coordinated by two amino groups from two different adjacent ligands (Na-N 2.529(3)/2.628(3) Å ). Reaction of 1 with LiNMe2 afforded the lithium alcoholate which crystallized as dimeric mixed-anion aggregate [(Me2NCH2)3COLi·LiNMe2]2 (4). It has a four-rung ladder structure consisting of two four-membered Li(NMe2)LiO rings connected through a central LiOLiO ring. All ligand amino groups are lithium-coordinated (Li-N 2.117(6)/2.101(6)/2.218(6) Å) as is the amido nitrogen atom (Li-N 1.964(6)/2.027(6) Å). Reaction of 1 with LitBu in n-hexane also led to deprotonation at oxygen. In addition, in one ligand one methyl group is deprotonated, in a second one two methyl groups are lithiated leading to doubly and triply charged anions, respectively. The product crystallizes as the dimeric mixed-anion aggregate [(−H2CN(Me)CH2)(Me2NCH2)2CO−·5 Li+· (−H2CN(Me)CH2)2(Me2NCH2)CO−]2 (5) having a core of 10 Li+ cations, 4 alcoholate oxygen atoms, and 6 N(Me)-CH2 − groups.