Linear tetranickel string complexes with mixed supported ligands and mixed-valence units [Ni2]3+: Synthesis, crystal structure, and magnetic studies
Journal
European Journal of Inorganic Chemistry
Journal Issue
20
Pages
3153-3159
Date Issued
2010
Author(s)
Abstract
The synthesis, crystal structures, and magnetic properties of linear tetranickel string complexes supported by mixed 2-(a-pyridylamino)-1,8- naphthyridine (Hpyany) and N-(p-tolylsulfonyl)dipyridyldiamine (H 2tsdpda) ligands are reported. In comparing the crystal structure of [Ni4(pyany)2(tsdpda)2Cl] (1) with that of [Ni4(pyany)2(tsdpda)2Cl(H2O)] (PF6) (2), the one-electron-reduced compound 1 displays shorter Ni(3)-Ni(4) (ca. 2.28 A) and longer Ni(3)-N (ca. 2.02 Å) bond lengths. Similar trends have also been observed for axial NCS--substituted derivatives [Ni4(pyany)2(tsdpda)2(NCS)] (3) and [Ni4(pyany)2(tsdpda)2(NCS)2] (4). These structural variations indicate the formation, of a mixed-valence [Ni 2]3+ unit and a three-electron, two-center Ni(4)-Ni(3) a bond. Magnetic measurements of 2 and 4 show that both terminal Ni(1) and Ni(4) ions are in the high-spin states (S = 1) and are antiferromagnetically coupled. The one-electron-reduced complexes 1 and 3, however, exhibit a delocalized mixed-valence [Ni2J3+ unit (S = 3/2), which is antiferromagnetically coupled with the terminal high-spin NiII ion. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Type
journal article