Mondal Arpan, Price Christopher G T, Steiner Alexander, Tang Jinkui, Layfield Richard A
Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9QJ, U.K.
Department of Chemistry, University of Liverpool, Crown St, Liverpool L69 7ZD, U.K.
Inorg Chem. 2025 Jul 7;64(26):13309-13317. doi: 10.1021/acs.inorgchem.5c01681. Epub 2025 Jun 25.
The oxidation state +2 is of interest in rare-earth chemistry since it allows these conventionally redox-inactive metals to be used as reducing agents. However, the divalent oxidation state is difficult to form for most rare-earth elements, and the ensuing compounds are often unstable. Here, we describe an approach to rare-earth reduction chemistry that circumvents the divalent oxidation state by using compounds of trivalent rare earths that store reducing electrons on the dinitrogen ligand [N], akin to "masked" divalent reactivity. Thus, the dinitrogen complexes (, M = Y, Gd, Tb, Dy, Cp = 1,2,4-CBuH) reduce hexaazatrinaphthylene and its hexamethyl derivative to give trimetallic , where the [RHAN] ligands (R = H, ; R = Me, ) form with = 1/2, and with elimination of N. The structures of and reveal that the -butyl substituents strongly influence the core geometry of these trimetallic complexes. Analysis of the magnetism and electronic structure of and identifies ferromagnetic metal-radical exchange, with coupling constants of = +2.87 cm and +3.07 cm, respectively (-2 formalism). The unusual ferromagnetic exchange is a consequence of charge transfer to the gadolinium 5d, 6s, and 6p orbitals from the radical ligands.
氧化态 +2 在稀土化学中备受关注，因为它能使这些传统上无氧化还原活性的金属用作还原剂。然而，对于大多数稀土元素而言，二价氧化态难以形成，且生成的化合物通常不稳定。在此，我们描述了一种稀土还原化学方法，该方法通过使用三价稀土化合物来规避二价氧化态，这些三价稀土化合物将还原电子存储在二氮配体 [N] 上，类似于“掩蔽”的二价反应活性。因此，二氮配合物（，M = Y、Gd、Tb、Dy，Cp = 1,2,4-CBuH）将六氮杂三亚萘及其六甲基衍生物还原，生成三金属配合物 ，其中 [RHAN] 配体（R = H，；R = Me，）以 = 1/2 形成，并消除 N。 和 的结构表明，叔丁基取代基强烈影响这些三金属配合物的核心几何结构。对 和 的磁性及电子结构分析确定了铁磁金属 - 自由基交换，其耦合常数分别为 = +2.87 cm 和 +3.07 cm（-2 形式）。这种不寻常的铁磁交换是自由基配体向钆 5d、6s 和 6p 轨道电荷转移的结果。
