Versatile Coordination Modes of Multidentate Neutral Amine Ligands with Group 1 Metal Cations

Abstract

This work comprehensively investigated the coordination chemistry of a hexa -dentate neutral amine ligand, namely, N,N′,N” - tris -(2- N -diethylaminoethyl)-1,4,7-triaza-cyclononane (DETAN), with group-1 metal cations (Li + , Na + , K + , Rb + , Cs + ). Versatile coordination modes were observed, from four-coordinate trigonal pyramidal to six-coordinate trigonal prismatic, depending on the metal ionic radii and metal’s substituent. For comparison, the coordination chemistry of a tetra -dentate tris -[2-(dimethylamino)ethyl]amine (Me 6 Tren) ligand was also studied. This work defines the available coordination modes of two multidentate amine ligands (DETAN and Me 6 Tren), guiding future applications of these ligands for pursuing highly reactive and elusive s-block and rare-earth metal complexes.

Elucidating Solution-State Coordination Modes of Multidentate Neutral Amine Ligands with Group-1 Metal Cations: Variable-Temperature NMR Studies

“…The other key fragment of the DETAN ligand is its TACN-based macrocycle backbone. The SCXRD solid-state structures 15 of 1 -Li/Na and 2 -Li/Na suggested that the N → M dative bonds in the macrocycles are much shorter compared to those in the sidearms (Δ N⃗M : ∼0.4 Å), indicating that the macrocycle is the structural dictating group, while the sidearms act as weakly bonded hemilabile pendant groups. To prove this hypothesis, the coordination behaviors of the macrocycle and the sidearms must be disentangled and studied separately.…”

“…Complex 4 was reported in our previous work. 15 The solid-state SCXRD structures of 3 and 4 ( 15 ) feature pseudo - C 3 v symmetries ( Figure 8 ).…”

“…14 Solid-state SCXRD studies revealed that the DETAN ligand features versatile coordination modes with Group-1 metal cations depending on the metal ionic radii and metal substituents. 15 We would like to bring to our readers' awareness that, other than the multidentate ligands (such as the DETAN), another strategy to isolate MeLi from its aggregates is via multimetallic chelating, such as in a Li 3 (μ-Me) complex [(thf) 3 Li 3 (μ-Me){(N t Bu) 3 S}] reported by the Stalke group in 2001, 16 and a Mo(μ-H)Li(μ-Me)Mo complex reported by the Carmona group in 2022. 17 In these two complexes, the anionic methyl group (CH 3 − ), though in its monomeric form, occupies a bridging position and shared by multiple metal sites.…”

Heavy Alkali Metal Manganate Complexes: Synthesis, Structures and Solvent‐Induced Dissociation Effects

“…We would advocate that it is now considered vital to include the whole of group 1 (Li ‐ Cs) when investigating catalytic performance, since gradations in reactivity can take place depending on which alkali metal is used. Investigations to gain more structural insights in whole series of group 1 complexes often exclude the heavier homologues due to the synthetic challenge or inaccessibility, [42,43] hence studies such as that by Schulz, [44] Roesky, [45] or Liddle, [46] in which light is shed on the whole of group 1 within the same ligand framework, remain exceptional. One of the most widely utilized ligands to study alkali metals in complexes are amide derivatives since they are of central importance in many chemical transformations as metallation and amide‐transfer reagents or as Brønsted bases [47–49] .…”

Mechanochemical Reduction and Doping of Cobalt (II,III) Oxide (Co3O4) by Lithium Metal: A Facile Route to LixCoyO Materials

“…However, this route has not been explored so far. In this context and based on our interest in lithium chemistry [23]- [25], we hypothesized that by introducing lithium metal as a reductant and a Li-ion source, and using mechanochemical methods to increase the reducibility of Co3O4, it is possible to deliver facile Co3O4 reduction and Li + doping in a one-pot manner. The findings are reported herein.…”