Maahs Adam C, Borg Genievieve C, Ghazzali Mohamed, Soldatov Dmitriy V, Rouzières Mathieu, Clérac Rodolphe, Preuss Kathryn E
Department of Chemistry, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Univ. Bordeaux, CNRS, CRPP, UMR 5031, F-33600, Pessac, France.
Chemistry. 2024 Dec 18;30(71):e202403220. doi: 10.1002/chem.202403220. Epub 2024 Nov 6.
A new paramagnetic ligand, 4-(2'-4-(2''-furyl)-pyrimidyl)-1,2,3,5-dithiadiazolyl (furylpymDTDA) and three transition metal coordination complexes, M(hfac)(furylpymDTDA) M=Mn, Co, Ni; hfac=1,1,1,5,5,5-hexafluoroacetylacetonato-), are reported. The solid-state structures are influenced by the geometry of the coordination sphere of the M(II) centers: trigonal (Mn) vs. octahedral (Co and Ni). While the hs-Mn(II) complex exhibits pairwise multi-centre 2-electron bonds (i. e., pancake bonds) between the planar π radical DTDA moieties, the hs-Co(II) and Ni(II) complexes crystallize with close contacts between coordinated furylpymDTDA radical ligands that define linear 1D arrays of molecular units. The magnetic data for the hs-Co(II) and Ni(II) complexes indicate ferromagnetic (FM) interactions between molecular units, apparently mediated by radical-radical contacts along the supramolecular chains. Computational analysis suggests proximity between regions of large α- and β-spin density on neighbouring molecular sites enabling FM exchange, in accordance with the McConnell I mechanism. The magnetic data for the Ni(II) complex are consistent with a Heisenberg spin chain, whereas the hs-Co(II) complex exhibits Ising-like spin chain behaviour and a magnetic phase transition to an FM ordered state at 4.6 K.
报道了一种新的顺磁性配体4-(2'-4-(2''-呋喃基)-嘧啶基)-1,2,3,5-二噻二唑基（呋喃基嘧啶二硫代二唑，furylpymDTDA）以及三种过渡金属配位络合物M(hfac)(furylpymDTDA)（M = Mn、Co、Ni；hfac = 1,1,1,5,5,5-六氟乙酰丙酮）。固态结构受M(II)中心配位球几何形状的影响：三角形（Mn）与八面体（Co和Ni）。虽然hs-Mn(II)络合物在平面π自由基DTDA部分之间表现出成对的多中心2电子键（即薄饼键），但hs-Co(II)和Ni(II)络合物结晶时，配位的呋喃基嘧啶自由基配体之间存在紧密接触，这些配体定义了分子单元的线性一维阵列。hs-Co(II)和Ni(II)络合物的磁性数据表明分子单元之间存在铁磁（FM）相互作用，显然是由沿超分子链的自由基-自由基接触介导的。计算分析表明，相邻分子位点上大α-和β-自旋密度区域之间接近，从而实现FM交换，这与麦康奈尔I机制一致。Ni(II)络合物的磁性数据与海森堡自旋链一致，而hs-Co(II)络合物表现出类伊辛自旋链行为，并在4.6 K时发生向FM有序态的磁相变。
