A novel complex[Na(Nrr-1-MeBzIm)3]ClO4(NIT-1-MeBzIm=2-{2-[(1-methyl)benzimidazolyl]}-4,4,5,5tetramethylimidazoline-1-oxyl-3-oxide)has been prepared and structurally characterized by elemental analysis,IR spectra and X-ray diffraction methods.The title complex crystallizes in trigonal,space group P-3 and Z=2.Crystal data:C45H57C1N12NaO10, M,=984.47,a=13.9411(8),b=13.9411(8),C=14.8622(16)(A),γ=120°,V=2501.5(3)(A)3,Dc= 1.307 g,cm3,μ(MoKα)=0.152 mm-1,F(000)=1038,R=0.0637 and wR=0.1813 for 1957 observed reflections with I>2σ(I).X-ray analysis reveals that the Na(I)ion is six-coordinated with three NIT-1-MeBzIm radicals.As we know,three radicals coordinating to the Na(1)ion in the main group by a chelate way is the first example.The Na(I) ion resides in a distorted octahedron with a facial configuration.Meanwhile,the intermolecular weak interactions result in a 2-D double layer conformation where the uncoordinated perchlorate anions are inserted in the packing space and take part in the H-bond interactions,and each complex is connected with six neighboring complexes and three perchlorate anions.