Interaction in crystals .106. The keyboard of Na-circle plus coordination numbers in its carbazole anion salts

Some local minima in the shallow potential of the system carbazole anion, sodium cation, and the ethers tetrahydrofuran, 1,2-dimethoxyethane, diglyme, triglyme, tetraglyme, 15-crown-5 as well as 2.2.1-cryptand are explored experimentally and by quantum-chemical calculations. Three prototype contact-ion multiples of Na+-solvated carbazole anion M(-) salts have been crystallized and structurally characterized: polyether-solvated monomers [M(-)Na(solv.)(+)](1), solvent-shared dimers [M(-)Na(solv.)(+)](2), and solvent-separated polyions [(M(-))(n)Na-solv.(+)]((n-1)-) [Na-solv.(+)]((n-1)). The Na+ coordination numbers stretch from 3 to 7 as illustrated by the compounds [(M(-))(3)Na+](--) [Na+(2.2.1-cryptand)](2) for 3 and 7, [(M(-))(2)Na+(THF)(2)](-) [Na+(2.2.1-cryptand)] for 4 and 7, [M(-)Na(+)(diglyme)](2) for 5, or [M(-)Na(+)(15-crown-5)] for 6. Structural comparison is based on literature analogies as well as on results of MNDO calculations concerning charge distribution and enthalpies of formation. Taken together, the results demonstrate the delicate energy balance, by which cation solvation can influence the formation of organic salts.