A new lanthanum (Ⅲ) nitrate complex with 1,10-dioxa-4,7,13,16 tetraaza-18-crown-6([18]N4O2) was prepared. The single crystal structure of {La[18]N4O2(NO3)3}·H2O was determined by X-ray diffraction method. It belongs to triclinic crystal system, space group P1 with a=1.0690(2)nm,b=1.3608(3)nm, c=0.8230(2)nm,α=103.10(3) °,β=104.71(3)°,γ=84.03(3)° ;Z=2,V=1.1265(4)mm^3,Dc=1.779g/cm^3,μ =1.968mm^-1,F(000) =608,R=0.0307,ωR=0.0566. Lanthanum ion is coordinated to the oxygen and nitrogen atoms of the macrocycle and also to the nitrate anions. The coordination number is twelve. The coordination polyhedron of the complex is distorted icosahedron.

Key words: LANTHANUM NITRATE, NITROGEN HETEROCYCLICS, CRYSTAL STRUCTURE, LANTHANUM COMPLEX, X-RAY DIFFRACTION ANALYSIS