The binding of lithium picrate (LiPic) to isomers L(1) and L(2) of the crown ether 2,2,7,7,12,12,17,17-octamethyl-21,22,23,24-tetraoxapentacyclo[16.2.1.1(3,6).1(8,11).1(13,16)]tetracosane (I) was studied spectrophotometrically in chloroform, chlorobenzene, and four ethereal solvents. In the latter, binding of L(1) to LiPic is weak, but L(2) yielded binding constants, K-c, of 60-7500 M(-1), depending on the solvating power of the ether. In chloroform (with 1% ethanol), L(2) gives an inclusion complex with a spectrum identical to that of a separated ion pair, and K-c = 1.2 x 10(6) M(-1), while L(2) gives an externally solvated LiPic ion pair complex. Complexations are remarkably slow due to the difficulty in rearranging L(1) and L(2) to conformations in which all four oxygen atoms have the proper orientation for effective complexation of the Li ion. In CHCl3, the complexation rate constant for L(1) is 7 x 10(2) M(-1) s(-1) and the decomplexation rate constant is 6 x 10(-4) s(-1). In chlorobenzene there is spectrophotometric evidence for the presence of 2:1 and 4:1 LiPic-crown ether complexes.