Is the corrolate macrocycle innocent or noninnocent? Magnetic susceptibility, Mössbauer, 1H NMR, and DFT investigations of chloro- and phenyliron corrolates.
Is the corrolate macrocycle innocent or noninnocent? Magnetic susceptibility, Mössbauer, 1H NMR, and DFT investigations of chloro- and phenyliron corrolates.
复制标题
相关的大周期是无辜的还是非无辜的？
DOI：
10.1021/ja012701h
复制
发表时间：
2002
影响因子：
15
通讯作者：
Trautwein,AlfredX
中科院分区：
文献类型：
--
作者：
Zakharieva,Olga;Schünemann,Volker;Gerdan,Michael;Licoccia,Silvia;Cai,Sheng;Walker,FAnn;Trautwein,AlfredX
为了确定（阴离子）铁腐蚀物的电子构型，即，无论它们是S = 1 Fe（IV）-corrosate（3-）还是S =3/2Fe（III）-corrosate（2-·），铁和大环电子之间的反铁磁耦合产生总的S = 1，八烷基corrosate铁的两个轴向配体配合物都通过变温磁化率，磁穆斯堡尔谱和1H NMR谱进行了研究，并将计算结果与自旋非限制DFT计算结果进行了比较。磁化率测量表明氯铁腐蚀物中存在一个非无辜的大环（腐蚀物（2-·）），与S =3/2Fe（III）中心有很强的反铁磁耦合，而苯铁腐蚀物的磁化率测量对电子构型没有决定性影响。这两种配合物的温度和场依赖性穆斯堡尔光谱研究产生的光谱可以用任何一种电子构型模拟，除了苯基铁配合物的异构体位移为-0.10mm/s，而氯铁配合物的异构体位移为+0.21mm/s，这表明前者中的铁是Fe（IV），而后者中的铁是Fe（III）。两种轴向配体配合物的1H NMR光谱研究显示在中间碳处有大的负自旋密度，与氯铁络合物（Cai，S.;步行者，F.一、Licoccia，S.Inorg.Chem.2000，39，3466）比苯基铁络合物的那些大大约4倍。苯铁配合物的质子化学位移与温度呈严格的线性关系。密度泛函理论的计算结果与氯铁络合物的公式一致：S1 =3/2Fe（III）-corrolate（2-·）S2=1/2，所有氮原子和中间碳原子的自旋密度为负，corrolate环的净自旋密度为−0.79，氯离子的自旋密度为正（+0.17），铁离子的自旋密度为+2.58。相比之下，苯基铁配合物的最佳公式为S = 1 Fe（IV）-corrolate（3-），但在大环的所有氮和中间碳上都有负自旋密度，而corrolate环上的净自旋密度几乎为零;苯基碳负离子碳的负自旋密度相对较大，为−0.15，铁为+2.05。根据以上结果，我们得出结论：在氯铁和苯基铁配合物中，腐蚀环都是非无辜的，但在氯铁配合物中腐蚀环的非无辜程度要比在苯基铁配合物中大得多。
In an attempt to determine the electron configuration of (anion)iron corrolates, i.e., whether they are S = 1 Fe(IV)-corrolate(3-) orS=3/2Fe(III)-corrolate(2-•), with antiferromagnetic coupling between the iron and macrocycle electrons to yield overallS= 1, two axial ligand complexes of an iron octaalkylcorrolate have been studied by temperature-dependent magnetic susceptibility, magnetic Mössbauer, and1H NMR spectroscopy, and the results have been compared to those determined on the basis of spin-unrestricted DFT calculations. Magnetic susceptibility measurements indicate the presence of a noninnocent macrocycle (corrolate (2-•)) for the chloroiron corrolate, with strong antiferromagnetic coupling to theS=3/2Fe(III) center, while those for the phenyliron corrolate are not conclusive as to the electron configuration. Temperature- and field-dependent Mössbauer spectroscopic investigations of these two complexes yielded spectra that could be simulated with either electron configuration, except that the isomer shift of the phenyl−iron complex is −0.10 mm/s while that of the chloroiron complex is +0.21 mm/s, suggesting that the iron in the former is Fe(IV) while in the latter it is Fe(III).1H NMR spectroscopic studies of both axial ligand complexes show large negative spin density at themesocarbons, with those of the chloroiron complex (Cai, S.; Walker, F. A.; Licoccia, S.Inorg. Chem.2000,39, 3466) being roughly four times larger than those of the phenyliron complex. The temperature dependence of the proton chemical shifts of the phenyliron complex is strictly linear. DFT calculations are consistent with the chloroiron complex being formulated asS1=3/2Fe(III)-corrolate (2-•)S2=1/2, with negative spin density at all nitrogens andmesocarbons, and a net spin density of −0.79 on the corrolate ring and positive spin density (+0.17) on the chloride ion and +2.58 on the iron. In contrast, the phenyliron complex is best formulated asS= 1 Fe(IV)-corrolate (3-), but again with negative spin density at all nitrogens andmesocarbons of the macrocycle, yet with the net spin density on the corrolate ring being virtually zero; the phenyl carbanion carbon has relatively large negative spin density of −0.15 and the iron +2.05. On the basis of all of the results, we conclude that inboththe chloroiron and phenyliron complexes the corrolate ring is noninnocent, in the chloroiron complex to a much larger extent than in the phenyliron complex.