Stamatatos Theocharis C, Escuer Albert, Abboud Khalil A, Raptopoulou Catherine P, Perlepes Spyros P, Christou George
Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA.
Inorg Chem. 2008 Dec 15;47(24):11825-38. doi: 10.1021/ic801555e.
Syntheses, crystal structures, and magnetochemical characterization are reported for the three new nickel(II) clusters Ni(14)(OH)(4)(N(3))(8)(pao)(14)(paoH)(2)(H(2)O)(2)(2) (1), Ni(12)Na(2)(OH)(4)(N(3))(8)(pao)(12)(H(2)O)(10)(2) (2), and Ni(5)(ppko)(5)(H(2)O)(7)(5) (3) (paoH = pyridine-2-carbaldehyde oxime, ppkoH = di-2-pyridyl ketone oxime). The reaction of Ni(ClO(4))(2).6H(2)O with paoH and NBu(n)(4)N(3) in H(2)O/MeCN in the presence of NEt(3), gave 1 in 65% yield. Complex 2 was obtained in 60% yield from the reaction of NiCl(2).6H(2)O with paoH and NaN(3) in H(2)O/MeCN in the presence of NaOH. The reaction of Ni(NO(3))(2).6H(2)O with ppkoH in EtOH in the presence of LiOH afforded complex 3 in 75% yield. The complexes all contain novel core topologies. The core of 1 comprises a central Ni(4) rhombus between two Ni(5). Complex 1 is the largest metal/oxime cluster discovered to date, as well as the first Ni(II)(14) coordination complex and the largest Ni(II)/N(3)(-) cluster. Complex 2 has a Ni(12)Na(2) topology that is very similar to that of 1, but with two central Ni(II) atoms of 1 replaced with Na(I) atoms. The core of 3 consists of four Ni(II) atoms forming a highly distorted tetrahedron, with the fifth Ni(II) atom lying almost on one of the edges. Variable-temperature, solid-state dc susceptibility and magnetization studies were carried out on complexes 1-3, and these were complemented with ac susceptibility data for 1 and 2. Fitting of the obtained M/(Nmu(B)) vs H/T data by matrix diagonalization and including axial zero-field splitting (D) gave ground-state spin (S) and D values of S = 6, D = -0.12(3) cm(-1) for 1 and S = 3, D = -0.20(5) cm(-1) for each of the two essentially noninteracting S = 3 Ni(6) subunits of 2. The data for 3 indicate antiferromagnetic exchange interactions and an S = 1 ground state. A simple 2-J model was found to be adequate to describe the variable-temperature dc susceptibility data. The combined work demonstrates the ligating flexibility of pao(-) and ppko(-), and their usefulness in the synthesis of polynuclear Ni(x) clusters with or without the presence of ancillary ligands.
报道了三种新型镍（II）簇合物Ni₁₄(OH)₄(N₃)₈(pao)₁₄(paoH)₂(H₂O)₂₂ (1)、Ni₁₂Na₂(OH)₄(N₃)₈(pao)₁₂(H₂O)₁₀₂ (2) 和 Ni₅(ppko)₅(H₂O)₇₅ (3)（paoH = 吡啶 - 2 - 甲醛肟，ppkoH = 二 - 2 - 吡啶基酮肟）的合成、晶体结构及磁化学表征。在三乙胺存在下，Ni(ClO₄)₂·6H₂O 与 paoH 和正丁基三乙铵叠氮化物在水/乙腈中反应，以 65%的产率得到 1。配合物 2 是在氢氧化钠存在下，NiCl₂·6H₂O 与 paoH 和叠氮化钠在水/乙腈中反应，以 60%的产率获得的。在氢氧化锂存在下，Ni(NO₃)₂·6H₂O 与 ppkoH 在乙醇中反应，以 75%的产率得到配合物 3。这些配合物均包含新颖的核心拓扑结构。1 的核心由两个 Ni₅之间的一个中心 Ni₄菱形组成。1 是迄今为止发现的最大的金属/肟簇合物，也是首个 Ni(II)₁₄配位配合物以及最大的 Ni(II)/N₃⁻簇合物。2 具有与 1 非常相似的 Ni₁₂Na₂拓扑结构，但 1 的两个中心 Ni(II)原子被 Na(I)原子取代。3 的核心由四个形成高度扭曲四面体的 Ni(II)原子组成，第五个 Ni(II)原子几乎位于一条边上。对配合物 1 - 3 进行了变温固态直流磁化率和磁化研究，并辅以 1 和 2 的交流磁化率数据。通过矩阵对角化并包括轴向零场分裂（D）对获得的 M/(NμB) 与 H/T 数据进行拟合，得出 1 的基态自旋（S）和 D 值为 S = 6，D = -0.12(3) cm⁻¹，以及 2 的两个基本不相互作用的 S = 3 Ni₆亚基中每个亚基的 S = 3，D = -0.20(5) cm⁻¹。3 的数据表明存在反铁磁交换相互作用且基态为 S = 1。发现一个简单的 2 - J 模型足以描述变温直流磁化率数据。综合研究表明了 pao⁻和 ppko⁻的配位灵活性，以及它们在合成有或没有辅助配体存在的多核 Niₓ簇合物中的有用性。
