Synthesis, Crystal Structure and Magnetic Properties of a Cobalt(Ⅱ) Complex with Quinoxaline-substituted Nitronyl Nitroxide Radicals

A new complex with the formula [Co（acac）;（NITQ）;]×2CH;Cl;1(acac = acetylacetone, NITQ = 2-（2′-quinoxalinyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), was synthesized and elucidated structurally as well as magnetically in detail. The crystal belongs to the monoclinic system, space group P2;/c with a = 9.6896（1）, b = 20.539（4）, c = 12.147（2） ?, β = 93.84（3）°, M;= 997.65, V = 2412.1（8） ?;, Z = 2, Dc = 1.374 g/cm, F（000） = 1038, m = 0.635 mm;, the final R = 0.0539 and w R = 0.1289 for 5998 observed reflections(I > 2σ（I）). The Co（Ⅱ） ion is coordinated by two nitrogen atoms of quinoxaline rings from two NITQs and four oxygen atoms from two acac ions to complete a distorted octahedral coordination environment. Compound 1 is further linked into a three-dimensional（3D） supramolecular network by hydrogen-bonding, Cl×××O weak contact and π···π stacking interactions. The magnetic measurements show compound 1 exhibits weak ferromagnetic interactions.