1 research outputs found
Elucidating Solution-State Coordination Modes of Multidentate Neutral Amine Ligands with Group‑1 Metal Cations: Variable-Temperature NMR Studies
Multidentate neutral amine ligands play vital roles in
coordination
chemistry and catalysis. In particular, these ligands are used to
tune the reactivity of Group-1 metal reagents, such as organolithium
reagents. Most, if not all, of these Group-1 metal reagent-mediated
reactions occur in solution. However, the solution-state coordination
behaviors of these ligands with Group-1 metal cations are poorly understood,
compared to the plethora of solid-state structural studies based on
single-crystal X-ray diffraction (SCXRD) studies. In this work, we
comprehensively mapped out the coordination modes with Group-1 metal
cations for three multidentate neutral amine ligands: tridentate 1,4,7-trimethyl-1,4,7-triazacyclononane
(Me3TACN), tetradentate tris[2-(dimethylamino)ethyl]amine
(Me6Tren), and hexadentate N,N′,N″-tris-(2-N-diethylaminoethyl)-1,4,7-triaza-cyclononane
(DETAN). The macrocycles in the Me3TACN and DETAN are identified
as the rigid structural directing motif, with the sidearms of DETAN
providing flexible “on-demand” coordination sites. In
comparison, the Me6Tren ligand features more robust coordination,
with the sidearms less likely to undergo the decoordinating–coordinating
equilibrium. This work will provide a guidance for coordination chemists
in applying these three ligands, in particular, the new DETAN ligand
to design metal complexes which suit their purposes