Coordination of 1,10-Phenanthroline and 2,2′-Bipyridine to Li⁺ in Different Ionic Liquids. How Innocent Are Ionic Liquids?

Abstract

On the basis of (7)Li NMR measurements, we have made detailed studies on the influence of the ionic liquids [emim][NTf(2)], [emim][ClO(4)], and [emim][EtSO(4)] on the complexation of Li(+) by the bidentate N-donor ligands 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). For each of the employed ionic liquids the NMR data implicate the formation of [Li(bipy)(2)](+) and [Li(phen)(2)](+), respectively. X-ray diffraction studies were performed to determine the coordination pattern in the solid state. In the case of [emim][ClO(4)] and [emim][EtSO(4)], crystal structures confirmed the NMR data, resulting in the complexes [Li(bipy)(2)ClO(4)] and [Li(phen)(2)EtSO(4)], respectively. On the contrary, the ionic liquid [emim][NTf(2)] generated the C(i) symmetric, dinuclear, supramolecular cluster [Li(bipy)(NTf(2))](2), where the individual Li(+) centers were found to be bridged by two [NTf(2)] anions. Density functional theory (DFT)-calculations lead to further information on the effect of stacking on the coordination geometry of the Li(+) centers.

A Novel Mechanism for the Extraction of Metals from Water to Ionic Liquids

“…However, extended X-ray absorption fine structure (EXAFS) studies of the same system that make use of the dicylohexano-18[crown]-6 crown ether demonstrate that the extracted complex exists as a divalent cation, [12] and it is known that NTf 2 is a weakly-binding anion that generally does not form strongly-coordinating complexes in solution. [17] The strontium-crown ether complex is therefore almost certainly not coordinated with NTf 2 in the IL phase. Scheme 2 compares the ion-exchange mechanism (rewritten relative to the form given in Scheme 1, but still valid) with that Scheme 1.…”

Tridentate phosphine ligands bearing aza-crown ether lariats

“…The Mo-Cl bond trans to the trialkylphosphine in [( 8b [Na])MoCl 3 ] + is marginally longer than that in ( 8a [Ca(OTf) 2 (THF)])MoCl 3 (2.4478(5) Å vs. 2.439(2) Å, respectively), thus there is a slight perturbation from the Mo–Cl⋯Na interaction on the ground state structure of the Mo(III) core. Unlike triflate, interactions between the triflimide anion with other alkali and alkaline earth metals are relatively rare outside of the parent salts [43–46]. The sodium is thus rendered sufficiently electrophilic to distort the crown (moving the nitrogen of the aza-crown to a pseudoaxial position) and interact with the Mo-bound chloride.…”

Nickel complexes of a binucleating ligand derived from an SCS pincer

“…This coordination mode has been reported for several complexes containing LiN(SO 2 CF 3 ) 2 . [36][37][38][39] The final ligand is the bromide ion that bridges to the Ni II ion. The Li-Br(1) distance is 2.71(2) for Li(1)-Br(1) and 2.99(2) Å for Li(1A)-Br(1).…”