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, Eu, Tb−Lu)

Abstract

The direct reaction of hydrated lanthanide nitrate salts with 18-crown-6 in 3∶1 CH3CN∶CH3OH has resulted in the isolation and structural characterization of [Pr(NO3)3(18-crown-6)] and [M(NO3)3(OH2)3]·18-crown-6 (M=Y, Eu, Tb−Lu). (The Eu and Yb analogs were confirmed with preliminary cell data only.) [Pr(NO3)3(18-crown-6)] is 12-coordinate icosahedral and crystallizes in the orthorhombic space group Pbca with (at 20°C)a=12.230(2),b=15.598(4),c=21.777(9)A andDcalc=1.89 g cm−3 forZ=8. The seven isostructural [Pr(NO3)3(18-crown-6)] complexes all contain 9-coordinate capped square antiprismatic metal centers hydrogen bonded via the bound water molecules to D3d 18-crown-6 within the lattice to form hydrogen bonded polymeric chains. Each complex is orthorhombic Pnma with cell parameters as follows: M=Tb (20°C):a=15.242(6),b=14.253(11),c=11.070(6)A,Dcalc=1.83 g cm−3 forZ=4; M=Dy (20°C):a=15.248(3),b=14.239(5),c=11.058(3)A,Dcalc=1.84 g cm−3 forZ=4; M=Y (19°C):a=15.260(2),b=14.238(2),c=11.048(3) A,Dcalc=1.64 g cm−3 for Z=4; M=Ho (20°C):a=15.226(4),b=14.208(15),c=11.028(3)A,Dcalc=1.86 g cm−3 forZ=4; M=Er (20°C):a=15.250(3),b=14.208(7),c=11.028(3)A,Dcalc=1.87 g cm−3 forZ=4; M=Tm (20°C):a=15.246(6),b=14.190(16),c=11.013(6) A,Dcalc=1.88 g cm−3 forZ=4; M=Lu (21°C):a=15.244(9),b=14.158(6),c=10.980(7)A,Dcalc=1.90 g cm−3 forZ=4.