Neutral thioether and selenoether macrocyclic coordination to Group 1 cations (Li-Cs) - synthesis, spectroscopic and structural properties.

The complexes [M(L)][BAr(F)] (BAr(F) = tetrakis{3,5-bis(trifluoromethyl)-phenyl}borate), L = [18]aneO4S2 (1,4,10,13-tetraoxa-7,16-dithiacyclooctadecane): M = Li-Cs; L = [18]aneO2S4 (1,10-dioxa-4,7,13,16-tetrathiacyclooctadecane): M = Li, Na, K; L = [18]aneO4Se2 (1,4,10,13-tetraoxa-7,16-diselenacyclooctadecane): M = Na, K, as well as [Na(18-crown-6)][BAr(F)], are obtained in good yield as crystalline solids by reaction of M[BAr(F)] with the appropriate macrocycle in dry CH2Cl2. X-ray crystallographic analyses of [Li([18]aneO4S2)][BAr(F)] and [Li([18]aneO2S4)][BAr(F)] show discrete distorted octahedral cations with hexadentate coordination to the macrocycle. The heavier alkali metal complexes all contain hexadentate coordination of the heterocrown, supplemented by MF interactions via the anions, producing extended structures with higher coordination numbers; Na: CN = 7 or 8; K: CN = 8; Rb: CN = 9; Cs: CN = 8 or 10. Notably, all of the structures exhibit significant M-S/Se coordination. The crystal structures of the potassium and rubidium complexes show two distinct M(heterocrown) cations, one with MF interactions to two mutually cis BAr(F) anions, and the other with mutually trans BAr(F) anions, giving 1D chain polymers. Solution multinuclear ((1)H, (13)C, (7)Li, (23)Na, (133)Cs) NMR data show that the macrocyclic coordination is retained in CH2Cl2 solution.