DIRECT COMPARISON OF THE PREPARATION AND STRUCTURAL FEATURES OF CROWN-ETHER AND POLYETHYLENE-GLYCOL COMPLEXES OF NDCL3.6H2O

The reactions of NdCl3.6H2O in 3/1 CH3CN/CH3OH with 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6, triethylene glycol (EO3), tetraethylene glycol (EO4), pentaethylene glycol (EO5), hexaethylene glycol (EO6), heptaethylene glycol (EO7), 1,5,9,13,17,21-hexathiacyclotetracosane-3,11,19-triol (S6OL), and 1,5,9,13-tetrathiacyclohexadecane-3,11-diol (S4OL) have been investigated. Many of the glycol complexes crystallize identically from H2O or the organic solvent. Competitive complexation between 12-crown-4 and EO4 favors crystallization of the glycol complex. A crystalline complex with 15-crown-5 directly coordinated to the Nd3+ ion could only be isolated by electrocrystallization. The use of LiCl as a salting out agent and the use of an excess of the glycol ligands were also investigated. X-ray structural analysis of the crystalline complexes was carried out. The complexes reported include the following. [NdCl3(15-crown-5)]: monoclinic, P2(1)/c, a = 8.174 (3) angstrom, b = 14.234 (5) angstrom, c = 14.180 (5) angstrom, beta = 104.80 (3)-degrees, D(calcd) = 1.93 g cm-3 for Z = 4. [NdCl(OH2)2(18-crown-6)]Cl2.2H2O: orthorhombic, P2(1)2(1)2(1), a = 7.438 (3) angstrom, b = 15.994 (4) angstrom, c = 18.966 (5) angstrom, D(calcd) = 1.73 g cm-3 for Z = 4. [Nd(EO4)2]4[NdCl6]Cl9: tetragonal, I422, a = 17.595 (6) angstrom, c = 17.257 (4) angstrom, D(calcd) = 1.74 g cm-3 for Z = 2. [NdCl2(OH2)(EO5)]Cl.H2O: monoclinic, P2(1)/c, a = 13.412 (2) angstrom, b = 9.780 (4) angstrom, c = 14.461 (3) angstrom, beta = 102.58 (1)-degrees, D(calcd) = 1.88 g cm-3 for Z = 4. [NdCl(OH2)(EO6)]Cl2: monoclinic, P2(1)/c, a = 7.485 (2) angstrom, b = 29.943 (5) angstrom, c = 9.197 (2) angstrom, beta = 99.99 (2)-degrees, D(calcd) = 1.80 g cm-3 for Z = 4. [Nd(OH2)2-(EO7)]Cl3.H2O: monoclinic, P2(1)/c, a = 9.053 (5) angstrom, b = 30.216 (9) angstrom, c = 9.691 (4) angstrom, beta = 113.77 (7)-degrees, D(calcd) = 1.73 g cm-3 for Z = 4. [Nd(OH2)7(OHMe)2]Cl3: orthorhombic, Pbca, a = 12.266 (2) angstrom, b = 12.614 (2) angstrom, c = 19.204 (1) angstrom, D(calcd) = 1.97 g cm-3 for Z = 8. Except for the 15-crown-5 complex, which is 8-coordinate, and the [Nd(EO4)2]3+ cation and heptaethylene glycol complex, which are 10-coordinate, the complexes are 9-coordinate tricapped trigonal prismatic. The glycol ligands all exhibit a helical wrapping pattern around the Nd3+ ions, while the larger crown ethers attempt to fold around the cations.