Ligand Structure and Complexation, XLVIII Alkali and Alkaline Earth Metal Ion Complexes of Bipyridine, Phenanthroline and Terpyridine

Abstract

Crystalline alkali and alkaline earth metal ion complexes of 2,2′‐bipyridine and 2,2′:6′,2″‐terpyridine are obtained and compared with known and new alkali and alkaline earth metal salt complexes of 1, 10‐phenanthroline.

Complexes of Group 1 Salts with N,N′‐Aromatic Bidentate Ligands, of 1 : 1 Salt : Base Ratio

“…[43,44]). Lithium thiocyanate or chloride complexes with phen or bpy, of 1:1 stoichiometry, and a 1:2 sodium thiocyanate complex with phen, obtained as hydrates, have later been reported, but not structurally characterized [45]. Phen been studied over many years as ionophores for alkali metal ions for use in ion-selective electrodes and fluorimetry [46], while NMR and vibrational spectroscopic studies of adducts of phen or bpy with group 1 salts have also been carried out [47Ϫ50].…”

The chemistry of the s- and p-block elements with 2,2′:6′,2′′-terpyridine ligands

“…117 It was suggested that the [M (tpy) 2 ] 2• diradical complexes possessed S 4 -symmetry; however, further insight into the structure of these complexes was not given by these authors. The same basically holds true for the assemblies Mg(NO 3 ) 101 Moreover, Emara et al gave evidence for the formation of a reasonably stable Mg II -tpy complex of 1 : 1 stoichiometry in water (K = 5.858 ± 0.023 mol −1 ). 118,119 Notably, Be II complexes with bidentate polypyridyl ligands were already reported in the early 1960s.…”

“…These results are in line with those made earlier by Vögtle et al, who combined Li(SCN) or Na (SCN) with tpy in solution. 101 These authors performed 23 Na NMR titration studies to qualitatively show the formation of the [Na(tpy)] + species. According to Shamsipur et al, the lg K 1 value for [Na(tpy)] + in MeNO 2 solution was 1.67, thus significantly lower as for [Li(tpy)] + (lg K 1 = 3.24).…”

“…The ammonium cation possesses similar properties as alkalimetal ions (according to Grimm's hydride-displacement law 103 ); however, this analogy did not apply with respect to the observed coordination behavior. 101 In order to suppress unfavorable interactions with solvent molecules and, thus, increase the stability of the tpy complexes, van Eldik et al opted for ionic liquids, specifically (emim)(NTf 2 ) and (emim)(ClO 4 ), to study the self-assembly of Li + ions and tpy in solution (emim: N-ethyl-N′-methylimidazolium; Tf: trifluoromethylsulfonyl). 104 Gutmann et al classified solvents according to their capability to act as donor-or acceptor-type molecules; the quantification, i.e., the determination of the donor or acceptor numbers (DN and AN, respectively) can be performed by NMR titration and/ or calorimetric experiments.…”

“…It has been demonstrated that heteronuclear NMR spectroscopy, making use of the NMR-active 7 Li and 23 Na nuclei, represents a versatile method to gain insight into the coordination behavior in solution. 101,104…”