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|標題:||Control of magnetic spin states by various mixed anionic ligands in trinickel complexes: synthesis, crystal structures and physical properties||作者:||Huang, M.Y.
|關鍵字:||metal string complexes;tripyridyldiamido dianion;electronic-properties;bonds;tetrapyridyltriamine;anisotropy;tpda(2-);chains;ncs;cl||Project:||Dalton Transactions||期刊/報告no：:||Dalton Transactions, Issue 48, Page(s) 5683-5690.||摘要:||
This study provides an opportunity to control the magnetic spin of nickel atoms using various mixed anionic ligands. A series of linear trinickel complexes supported by two kinds of ligands, oligo-alpha-pyridylamido and sulfonyl amido/amido, were synthesized and their structures were determined by X-ray diffraction. The three nickel atoms of [Ni-3(Lpts)(2)(dpa)(2)](1) (dpa(-) = dipyridylamido, Lpts(2-) = N,N'-bis(p-toluenesulfonyl)pyridyldiamido) display short Ni-N (similar to 1.90 angstrom) bond distances, which are consistent with a low spin state of Ni(II) ions, and exhibit spin states of ( 0, 0, 0) for the three Ni( II) ions. One of the terminal Ni(II) ions of [Ni-3(Lms)(2)(dpa)(2)(H2O)] (2) (Lms(2-) = N,N'-bis(4-methylsulfonyl)-pyridyldiamido) and [Ni-3(Lpts)(2)(pepteaH(2))] (4) (pepteaH(2)(2-) = pentapyridyldiamidodiamine) bonded with an axial ligand exhibits a square pyramidal (NiN4X) geometry with long Ni-N bond distances (similar to 2.10 angstrom) which are consistent with a high spin Ni(II) configuration. The spin states of these trinickel complexes are ( 1, 0, 0). Complex 2 and 6 can be interchanged by the removal or addition of an axial water molecule. The structural features of 6 are comparable with those of 1. Both the terminal Ni(II) ions in [Ni-3(LAc)(2)(dpa)(2)] (3) (Lac(2-) = N,N'-biacetyl-pyridyldiamido) are in square pyramidal geometry and exhibit high spin. The spin states of the nickel ions in 3 are (1, 0, 1), and the two terminal nickel ions exhibit antiferromagnetic interactions. The molecular structure of [Ni-3(Lpts)(2)(dpa)(2)](BF4) (5), which was obtained by the one-electron oxidation of 1, is similar to those of the neutral analogue 1, except for the presence of a counter anion to compensate for the positive charge on the Ni-3 core. All of the Ni-Ni bond lengths of 5 are slightly shorter (ca. 0.05 angstrom) than those in the neutral analogues. This is attributed to the formation of partial Ni-Ni bonding.
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