Prediction of ion selectivity by quantum chemical calculations X: A recent (personal) review

Host-Guest Complexes of Two Isomeric 2,2’-Bioxazole Based {2}-Lehn-Type Cryptands. Prediction of Ion Selectivity by Quantum Chemical Calculations. Part XIV

“…[19] These observations can be easily rationalized by comparing the cation-nitrogen and cation-oxygen interaction properties extant in our solvent complexes [M(Furan) n ] m+ , [M(Pyridine) n ] m+ , [M(NH 3 ) n ] m+ (Tables 2, 3) and in the literature [M(H 2 O) n ] m+ . [19] Comparing the bond lengths of a given cation with oxygen or a nitrogen donor of the same hybridizations, one obtains consequently longer M m+ -N interactions than M m+ -O interactions. This leads to the situation that a cavity that will select the same cation based on N-coordination as well as one based on O-coordination, has to be of greater magnitude.…”

“…In the field of computational chemistry two criteria have proven to be reliable for the prediction of selective ion complexation. [19,20] a) Comparison of the energy values obtained from the construction of model reactions. b) Monitoring of the geometry and variations of it in the host-guest complexes, and comparison with appropriate references.…”

“…[22] ; d(M-N NH3 ): taken from ref. [19] ; d(M-O furan ): calculated at the same theory level (RB3LYP/LANL2DZp). Metal ions…”

“…[22] ; d(M-N pyr ) and d(M-N NH3 ): ref. [19] and [M(H 2 O) n ] m+ (n = 4 for Li + and Be 2+ and n = 6 for all others) is depicted in Figures 4 and 5. The bisecting lines in the figures represent the cases in which coordination will fit most satisfactorily, where ions above the line are undoubtedly too small, whereas the ions below the line are too large for a proper coordination in the studied macromolecular cages.…”

“…phen.phen], 2 prefers the ions Na + and Mg 2+ thus exhibiting a cavity comparable to that of dodeka(ethylene)octamine (Bühl's cryptand) and [2.1.1]. [19] These observations can be easily rationalized by comparing the cation-nitrogen and cation-oxygen interaction properties extant in our solvent complexes [M(Furan) n ] m+ , [M(Pyridine) n ] m+ , [M(NH 3 ) n ] m+ (Tables 2, 3) and in the literature [M(H 2 O) n ] m+ . [19] Comparing the bond lengths of a given cation with oxygen or a nitrogen donor of the same hybridizations, one obtains consequently longer M m+ -N interactions than M m+ -O interactions.…”