Boudalis Athanassios K, Lalioti Nikolia, Spyroulias Georgios A, Raptopoulou Catherine P, Terzis Aris, Bousseksou Azzedine, Tangoulis Vassilis, Tuchagues Jean-Pierre, Perlepes Spyros P
Department of Chemistry, University of Patras, 26504 Patras, Greece.
Inorg Chem. 2002 Dec 2;41(24):6474-87. doi: 10.1021/ic025795k.
The preparations, X-ray structures, and detailed physical characterizations are presented for three new tetranuclear Fe(III)/RCO(2)(-)/phen complexes, where phen = 1,10-phenanthroline: Fe(4)(OHO)(OH)(2)(O(2)CMe)(4)(phen)(4)(3).4.4MeCN.H(2)O (1.4.4MeCN.H(2)O); Fe(4)O(2)(O(2)CPh)(7)(phen)(2).2MeCN (2.2MeCN); [Fe(4)O(2)(O(2)CPh)(8)(phen)(2)].2H(2)O (3.2H(2)O). Complex 1.4.4MeCN.H(2)O crystallizes in space group P2(1)/n, with a = 18.162(9) A, b = 39.016(19) A, c = 13.054(7) A, beta = 104.29(2) degrees, Z = 4, and V = 8963.7 A(3). Complex 2.2MeCN crystallizes in space group P2(1)/n, with a = 18.532(2) A, b = 35.908(3) A, c = 11.591(1) A, beta = 96.42(1) degrees, Z = 4, and V = 7665(1) A(3). Complex 3.2H(2)O crystallizes in space group I2/a, with a = 18.79(1) A, b = 22.80(1) A, c = 20.74(1) A, beta = 113.21(2) degrees, Z = 4, and V = 8166(1) A(3). The cation of 1 contains the novel Fe(4)(mu(4)-OHO)(mu-OH)(2) core. The core structure of 2 and 3 consists of a tetranuclear bis(mu(3)-O) cluster disposed in a "butterfly" arrangement. Magnetic susceptibility data were collected on 1-3 in the 2-300 K range. For the rectangular complex 1, fitting the data to the appropriate theoretical chi(M) vs T expression gave J(1) = -75.4 cm(-1), J(2) = -21.4 cm(-1), and g = 2.0(1), where J(1) and J(2) refer to the Fe(III)O(O(2)CMe)(2)Fe(III) and Fe(III)(OH)Fe(III) pairwise exchange interactions, respectively. The S = 0 ground state of 1 was confirmed by 2 K magnetization data. The data for 2 and 3 reveal a diamagnetic ground state with antiferromagnetic exchange interactions among the four high-spin Fe(III) ions. The exchange coupling constant J(bb) ("body-body" interaction) is indeterminate due to prevailing spin frustration, but the "wing-body" antiferromagnetic interaction (J(wb)) was evaluated to be -77.6 and -65.7 cm(-1) for 2 and 3, respectively, using the appropriate spin Hamiltonian approach. Mössbauer spectra of 1-3 are consistent with high-spin Fe(III) ions. The data indicated asymmetry of the Fe(4) core of 1 at 80 K, which is not detected at room temperature due to thermal motion of the core. The spectra of 2 and 3 analyze as two quadrupole-split doublets which were assigned to the body and wing-tip pairs of metal ions. (1)H NMR spectra are reported for 1-3 with assignment of the main resonances.
本文介绍了三种新型四核铁（III）/RCO₂⁻/邻菲啰啉配合物的制备、X射线结构及详细物理表征，其中邻菲啰啉（phen）= 1,10 - 邻菲啰啉：Fe₄(OHO)(OH)₂(O₂CMe)₄(phen)₄₃·4.4MeCN·H₂O（1·4.4MeCN·H₂O）；Fe₄O₂(O₂CPh)₇(phen)₂·2MeCN（2·2MeCN）；[Fe₄O₂(O₂CPh)₈(phen)₂]·2H₂O（3·2H₂O）。配合物1·4.4MeCN·H₂O结晶于空间群P2₁/n，a = 18.162(9) Å，b = 39.016(19) Å，c = 13.054(7) Å，β = 104.29(2)°，Z = 4，V = 8963.7 ų。配合物2·2MeCN结晶于空间群P2₁/n，a = 18.532(2) Å，b = 35.908(3) Å，c = 11.591(1) Å，β = 96.42(1)°，Z = 4，V = 7665(1) ų。配合物3·2H₂O结晶于空间群I2/a，a = 18.79(1) Å，b = 22.80(1) Å，c = 20.74(1) Å，β = 113.21(2)°，Z = 4，V = 8166(1) ų。配合物1的阳离子包含新型Fe₄(μ₄ - OHO)(μ - OH)₂核心。配合物2和3的核心结构由呈“蝴蝶”排列的四核双（μ₃ - O）簇组成。在2 - 300 K范围内收集了配合物1 - 3的磁化率数据。对于矩形配合物1，将数据拟合到合适的理论χ(M)对T表达式，得到J₁ = -75.4 cm⁻¹，J₂ = -21.4 cm⁻¹，g = 2.0(1)，其中J₁和J₂分别指Fe(III)O(O₂CMe)₂Fe(III)和Fe(III)(OH)Fe(III)的成对交换相互作用。2 K磁化数据证实了配合物1的S = 0基态。配合物2和3的数据显示四个高自旋Fe(III)离子之间存在反铁磁交换相互作用的抗磁性基态。由于普遍存在的自旋阻挫，交换耦合常数J(bb)（“体 - 体”相互作用）不确定，但使用合适的自旋哈密顿方法，配合物2和3的“翼 - 体”反铁磁相互作用（J(wb)）分别评估为-77.6和-65.7 cm⁻¹。配合物1 - 3的穆斯堡尔谱与高自旋Fe(III)离子一致。数据表明配合物1的Fe₄核心在80 K时不对称，由于核心的热运动，在室温下未检测到。配合物2和3的谱分析为两个四极分裂双峰，分别归属于金属离子的体和翼尖对。报告了配合物1 - 3的¹H NMR谱并归属了主要共振峰。
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