||aDeh-Yu College of Nursing and Management, Keelung, Taiwan 203, R.O.C. bDepartment of Chemistry, Tamkang University, Tamsui, Taiwan 251, R.O.C. cInstrument Center, College of Science, National Taiwan University, Taipei, Taiwan, R.O.C. ZnCl2(NIT-pPy) 1, (NIT-pPy = 2-(4-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide) crystallizes in the orthorhombic space group Pnn2 with the cell parameters a = 9.4083(9), b = 39.686(3), c = 7.4417(14) A. ZnCl2(NIT-6M-oPy) 2, (NIT-6M-oPy = 2-(6-methyl-2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide) crystallizes in the monoclinic space group Pn with a = 7.377(2), b = 19.096(4), c = 11.853(2) A, b = 95.65(3)°. The temperature dependence magnetic susceptibility of complex 1 revealed an intermolecular ferromagnetic exchange interaction. A simple spin-polarization model has been used to justify the observed ferromagnetic exchange interaction between the spins of the radical NO group in complex 2.