Effect of the solvent on the reaction of a crown ether with yttrium thiocyanate

Abstract A one pot reaction of [Y(H2O)5(NCS)3]·H2O with 18-crown-6 in acetonitrile (MeCN), tetrahydrofuran (thf), ethyl acetate (EtOAc), and i-PrOH solutions under ambient conditions gives hitherto unknown compounds identified as completely dehydrated [Y(18-crown-6)(NCS)3] (1) and [Y(18-crown-6)(NCS)3]·nA (A = MeCN, thf, 18-crown-6) (2) with the inner-sphere coordination of the macrocyclic polyether. The central atom in compound 2 is coordinated by six oxygen atoms of the macrocycle and three nitrogen atoms of the thiocyanate ions. The coordination number of yttrium is 9. The solvent effect on the transition from endo- to exo-binding of 18-crown-6 with [Y(H2O)5(NCS)3] has been identified. The thermal behavior of complexes 1 and 2 has been studied. Dehydrated samples of 1 and 2 are not hygroscopic, do not undergo hydrolysis, and are stable in the air. The photoluminescence of compounds 1 and 2 is due to T1→S0 fluorescence of the thiocyanate ion.