Synthesis and Electronic Ground-State Properties of Pyrrolyl-Based Iron Pincer Complexes: Revisited
Synthesis and Electronic Ground-State Properties of Pyrrolyl-Based Iron Pincer Complexes: Revisited
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DOI：
10.1021/acs.inorgchem.7b01078
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发表时间：
2017-07-17
影响因子：
4.6
通讯作者：
Walter, Marc D.
中科院分区：
文献类型：
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作者：
Ehrlich, Nico;Kreye, Markus;Walter, Marc D.
合成了吡咯基铁钳化合物[((PNP)-P-TBU)FeCl](1)、[((PNP)-P-TBU)FeN_2](2)和[(TBuPNP)Fe(CO)(2)](3)，并对其结构进行了表征。此外，还用固体磁化率、零场Fe-57穆斯堡尔谱和X波段电子顺磁共振光谱等技术研究了它们的电子基态。铁(II)起始原料1处于中间自旋(S=1)状态，而铁(I)还原产物2和3呈现低自旋(S=1/2)基态。零场~(57)Fe穆斯堡尔谱显示出典型的大四极分裂(即约为3.7 mm S(-1))，而固态磁化率数据则显示出明显的零场分裂(|D|约为37 cm(-1))，与1的中自旋组态一致。铁(I)物种2和3的有效磁矩比仅自旋值的预期大，表明基态轨道角动量不完全熄灭，存在自旋轨道耦合。实验结果得到了密度泛函理论计算的补充，与实验数据吻合较好。最值得注意的是，这些计算揭示了络合物1的低激发态(S=2)；此外，计算的所有络合物的穆斯堡尔参数与实验结果非常一致。
The pyrrolyl-based iron pincer compounds [((PNP)-P-tBu)FeCl] (1), [((PNP)-P-tBu)FeN2] (2), and [(tBuPNP)Fe(CO)(2)] (3) were prepared and structurally characterized. In addition, their electronic ground states were probed by various techniques including solid-state magnetic susceptibility and zero-field Fe-57 Mossbauer and X-band electron paramagnetic resonance spectroscopy. While the iron(II) starting material 1 adopts an intermediate-spin (S = 1) state, the iron(I) reduction products 2 and 3 exhibit a low-spin (S = 1/2) ground state. Consistent with an intermediate-spin configuration for 1, the zero-field 57Fe Mossbauer spectrum shows a characteristically large quadrupole splitting (iE(Q) approximate to 3.7 mm s(-1)), and the solid-state magnetic susceptibility data show pronounced zero-field splitting (|D| approximate to 37 cm(-1)). The effective magnetic moments observed for the iron(I) species 2 and 3 are larger than expected from the spin-only value and indicate an incompletely quenched orbital angular momentum and the presence of spinorbit coupling in the ground state. The experimental findings are complemented by density functional theory computations, which are in good agreement with the experimental data. Most notably, these calculations reveal a low-lying (S = 2) excited state for complex 1; furthermore, the computed Mossbauer parameters for all complexes studied herein are in excellent agreement with the experimental findings.