Mikhailenko Maxim V, Ivanov Vladislav V, Shestakov Alexander F, Kuzmin Aleksey V, Khasanov Salavat S, Otsuka Akihiro, Yamochi Hideki, Kitagawa Hiroshi, Konarev Dmitri V
Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS, Chernogolovka, Moscow region, 142432, Russia.
Moscow State University, Leninskie Gory, Moscow, 119991 Russia.
Dalton Trans. 2023 Aug 15;52(32):11222-11233. doi: 10.1039/d3dt01571h.
A series of trianion assemblies of hexaazatriphenylenehexacarbonitrile {HAT(CN)} and hexaazatrinaphthylenehexacarbonitrile {HATNA(CN)} with three Fe(II) or Co(II) ions: {cryptand(K)}·{HATNA(CN)·(FeI)}·2CHCl (1), {cryptand(K)}·{HATNA(CN)·(CoI)}·2CHCl (2), and (CV)·{HAT(CN)·(CoCl)}·0.5(CVCl)·2.5CHCl (3) are synthesized (CVCl = crystal violet). Salt 1 has a value of 9.80 emu K mol at 300 K, indicating a contribution of three high-spin Fe ( = 2) and one = 1/2 of HATNA(CN)˙. The value increases with cooling up to 12.92 emu K mol at 28 K, providing a positive Weiss temperature of +20 K. Such behavior is described using a strong antiferromagnetic coupling between = 2 and = 1/2 with = -82.1 cm and a weaker Fe-Fe antiferromagnetic coupling with = -7.0 cm. As a result, the spins of three Fe(II) ions ( = 2) align parallel to each other forming a high-spin = 11/2 system. Density functional theory (DFT) calculations support a high-spin state of Co ( = 3/2) for 2 and 3. However, the value of 2 and 3 is 2.25 emu K mol at 300 K, which is smaller than 6 emu K mol calculated for the system with three independent = 3/2 and one = 1/2 spins. In contrast to 1, the values decrease with cooling to 0.13-0.36 emu K mol at 1.9 K, indicating that spins of cobalt atoms align antiparallel to each other. Data fitting using PHI software for the model consisting of three high-spin Co(II) ions and an = 1/2 radical ligand shows very large Co-L˙ coupling for 2 and 3 with values of -442 and -349 cm. The Co-Co coupling the ligand () is also large, being -100 and -84 cm, respectively, which is more than 10 times larger than that of 1. One of the reasons for the increase may be the shortening of the Co-N(L) bonds in 3 and 2 to 2.02(2) and 1.993(12) Å. DFT calculations support the population of the quartet state for the Co system, whereas the high-spin decet ( = 9/2) state is positioned higher by 680 cm and is not populated at 300 K. This is explained by the large Co-Co coupling. Thus, a balance between and couplings provides parallel or antiparallel alignment of the Fe and Co spins, leading to high- or low-spin ground states of {L·[M(Hal)]}.
一系列由六氮杂三亚苯基六腈{HAT(CN)}和六氮杂三萘并萘六腈{HATNA(CN)}与三个Fe(II)或Co(II)离子形成的三阴离子配合物：{穴醚(K)}·{HATNA(CN)·(FeI)}·2CHCl (1)、{穴醚(K)}·{HATNA(CN)·(CoI)}·2CHCl (2)以及(CV)·{HAT(CN)·(CoCl)}·0.5(CVCl)·2.5CHCl (3)被合成出来（CVCl = 结晶紫）。盐1在300 K时的 值为9.80 emu K mol，表明有三个高自旋Fe（ = 2）以及一个 = 1/2的HATNA(CN)˙的贡献。该 值随着冷却升高，在28 K时达到12.92 emu K mol，给出了 +20 K的正韦斯温度。这种行为可以用 = 2和 = 1/2之间的强反铁磁耦合（ = -82.1 cm）以及较弱的Fe - Fe反铁磁耦合（ = -7.0 cm）来描述。结果，三个Fe(II)离子（ = 2）的自旋彼此平行排列，形成一个高自旋 = 11/2体系。密度泛函理论（DFT）计算支持2和3中Co（ = 3/2）的高自旋态。然而，2和3在300 K时的 值为2.25 emu K mol，小于具有三个独立的 = 3/2和一个 = 1/2自旋的体系计算得到的6 emu K mol。与1相反，2和3的值随着冷却在1.9 K时降至0.13 - 0.36 emu K mol，表明钴原子的自旋彼此反平行排列。使用PHI软件对由三个高自旋Co(II)离子和一个 = 1/2自由基配体组成的模型进行数据拟合，结果显示2和3具有非常大的Co - L˙耦合， 值分别为 -442和 -349 cm。Co-Co与配体（）的耦合也很大，分别为 -100和 -84 cm，比1大10倍以上。 值增加其中一个原因可能是3和2中Co - N(L)键缩短至2.02(2)和1.993(12) Å。DFT计算支持Co体系的四重态，而高自旋十重态（ = 9/2）的能量高出680 cm，在300 K时未出现。这可以用大的Co - Co耦合来解释。因此， 和 耦合之间的平衡导致Fe和Co自旋的平行或反平行排列，从而产生{L·[M(Hal)]}的高自旋或低自旋基态。
