Aramburu J A, Moreno M
Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain.
J Phys Chem A. 2021 Mar 25;125(11):2284-2293. doi: 10.1021/acs.jpca.0c11609. Epub 2021 Mar 16.
Using first-principles calculations, we show that the origin of the intrinsic a(∼3 - )-b(∼ - ) splitting, Δ, in tetragonal transition-metal complexes and the variations of the cubic field splitting, 10, with the metal-ligand distance, , are much more subtle than commonly thought. As a main novelty, the key role played by covalent bonding with deep valence ligand levels and thus the inadequacy of too simple models often used for the present goal is stressed. Taking as a guide the isolated CuF complex, it is proved that Δ essentially arises from bonding with deep 2s(F) orbitals despite them lying ∼23 eV below 2p(F) orbitals. This conclusion, although surprising, is also supported by results on octahedral fluoride complexes where the contribution to 10 splitting from bonding with 2s(F) orbitals is behind its strong dependence, stressing that explanations based on the crystal-field approach are simply meaningless.
通过第一性原理计算，我们表明，四方过渡金属配合物中本征a(∼3 - )-b(∼ - )分裂Δ的起源以及立方场分裂10随金属 - 配体距离的变化比通常认为的要微妙得多。作为一个主要的新颖之处，强调了与深价配体能级的共价键所起的关键作用，以及因此对于当前目标而言常用的过于简单模型的不足之处。以孤立的CuF配合物为指导，证明了Δ本质上源于与深2s(F)轨道的键合，尽管这些轨道比2p(F)轨道低约23 eV。这一结论虽然令人惊讶，但也得到了八面体氟化物配合物结果的支持，其中与2s(F)轨道键合对10分裂的贡献在其强烈依赖性之后，强调基于晶体场方法的解释根本没有意义。
