Primary to secondary sphere coordination of 18-crown-6 to lanthanide (III) nitrates: Structural analysis of [Pr(NO3)3-(18-crown-6)] and [M(NO3)3(OH2)3].18-crown-6 (M=Y, Bu, Tb―Lu)

The direct reaction of hydrated lanthanide nitrate salts with 18-crown-6 in 3:1 CH{sub 3}CN:CH{sub 3}OH has resulted in the isolation and structural characterization of [Pr(NO{sub 3}){sub 3}(18-crown-6)] and [M(NO{sub 3}){sub 3}(OH{sub 2}){sub 3}]{center_dot}18-crown-6 (M=Y, Eu, Tb-Lu). (The Eu and Yb analogs were confirmed with preliminary cell data only). [Pr(NO{sub 3}){sub 3}(18-crown-6)] is 12-coordinate icosahedral and crystallizes in the orthorhombic space group Pbca with (at 20{degrees}C) a = 12.230(2), b = 15.598(4), c = 21.777(9) {angstrom} and D{sub calc} = 1.89 g cm{sup -3} for Z = 8. The seven isostructural [Pr(NO{sub 3}){sub 3}(18-crown-6)] complexes all contain 9-coordinate capped square antiprismatic metal centers hydrogen bonded via the bound water molecules to D{sub 3d} 18-crown-6 within the lattice to form hydrogen bonded polymeric chains.