Ground-state electronic and magnetic properties of a mu3-oxo-bridged trinuclear Cu(II) complex: correlation to the native intermediate of the multicopper oxidases.
Ground-state electronic and magnetic properties of a mu3-oxo-bridged trinuclear Cu(II) complex: correlation to the native intermediate of the multicopper oxidases.
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mu3-氧桥三核 Cu(II) 配合物的基态电子和磁性特性：与多铜氧化酶的天然中间体的相关性。
DOI：
10.1021/ic0507870
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发表时间：
2005
影响因子：
4.6
通讯作者：
Solomon,EdwardI
中科院分区：
文献类型：
--
作者：
Yoon,Jungjoo;Solomon,EdwardI
用C3对称的Cu3II络合物μ3O计算了多铜氧化酶天然中间体(NI)中三核CuIIsite的一种可能结构--μ3-氧桥联结构的基态电子和磁性.μ3O的独特之处在于，除了氧代外，没有其他配体对交换偶联起作用。然而，μ3O具有铁磁性基态，这与NiI的基态不一致。因此，考虑了两种微扰： 3-氧代配体的μ质子化和μ3-氧代配体向Cu3平面的驰豫。值得注意的是，当氧代配体足够接近Cu3平面(-lt；0.3？)时，μ3O的基态变为反铁磁性，并且可以与NiI的基态相关联。此外，从变温电子顺磁共振中发现μ_3O的铁磁性4A基态经历了2D=−5.0 cm~(-1)的零场分裂，这是由二阶各向异性交换引起的。这使得对σ到π激发态交换路径的评估成为可能，并提供了实验证据，证明反铁磁性μ3O的轨道简并的2E基态也将经历与各向异性交换具有相同物理起源的一阶反对称交换的零FS。讨论了μ3-OXO桥对引起各向同性、反对称和各向异性交换的地-地和地-激发态超交换路径的重要贡献。
The ground-state electronic and magnetic properties of one of the possible structures of the trinuclear CuIIsite in the native intermediate (NI) of the multicopper oxidases, the μ3-oxo-bridged structure, are evaluated using theC3-symmetric Cu3IIcomplex, μ3O. μ3O is unique in that no ligand, other than the oxo, contributes to the exchange coupling. However, μ3O has a ferromagnetic ground state, inconsistent with that of NI. Therefore, two perturbations have been considered: protonation of the μ3-oxo ligand and relaxation of the μ3-oxo ligand into the Cu3plane. Notably, when the oxo ligand is sufficiently close to the Cu3plane (<0.3 Å), the ground state of μ3O becomes antiferromagnetic and can be correlated to that of NI. In addition, the ferromagnetic4A ground state of μ3O is found from variable-temperature EPR to undergo a zero-field splitting (ZFS) of 2D= −5.0 cm-1, which derives from the second-order anisotropic exchange. This allows evaluation of the σ-to-π excited-state exchange pathways and provides experimental evidence that the orbitally degenerate2E ground state of the antiferromagnetic μ3O would also undergo a ZFS by the first-order antisymmetric exchange that has the same physical origin as the anisotropic exchange. The important contribution of the μ3-oxo bridge to the ground-to-ground and ground-to-excited-state superexchange pathways that are responsible for the isotropic, antisymmetric, and anisotropic exchanges are discussed.