A New Quinoxalinyl-Substituted Nitronyl Nitroxide Radical and its Five-Spin Cu-II and Four-Spin Mn-II Complexes: Syntheses, Crystal Structures, and Magnetic Properties
- 经济学院－已发表论文 
A new radical of QNXL-2NIT (1) (QNXL-2NIT = 2-(2-quinoxalinyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) and its complexes [Cu(hfac)(2)](3)(QNXL-2NIT)(2)center dot 2CHCl(3) (2) and [Mn(hfac)(2)](2)(QNXL-2NIT)(2) (3) (hfac = 1,1,1,5,5,5-hexfluoroacetylacetone) were first reasonably designed and synthesised in this paper. The X-ray structure determination revealed that by introducing the quinoxalinyl ring group to the nitronyl nitroxide radical, QNXL-2NIT affords more coordination sites for metal ions. We successfully obtained its copper complex with linear tri-nuclear five-spin structure. However, when we substituted Mn-II as the central metal, complex 3 exhibits a rectangle-like four-spin framework containing two Mn-II ions and two radicals in one molecule. The magnetic study of the two complexes shows that there are strong antiferromagnetic interactions between the radical and the terminal Cu-II ions with g = 2.25, J = -291.67 cm(-1) and zJ(1) = -0.25 cm(-1) and the dominating interactions between the Mn-II ion and the radical in complex 3 are also antiferromagnetic with the parameters of g 1.99, J(1) = -77.00 cm(-1) and J(2) = 0.34 cm(-1).