Pulsed EPR investigations of systems modeling molybdenum enzymes:: Hyperfine and quadrupole parameters of OXO-17O in [MO17O(SPh)4]-
Pulsed EPR investigations of systems modeling molybdenum enzymes:: Hyperfine and quadrupole parameters of OXO-17O in [MO17O(SPh)4]-
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DOI：
10.1021/ja055472y
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发表时间：
2005-11-30
影响因子：
15
通讯作者：
Enemark, JH
中科院分区：
文献类型：
--
作者：
Astashkin, AV;Neese, F;Enemark, JH
用K-a带ESEEM光谱法测定了[（MOO）-O-17（SPh）（4）]（-）中氧代-O-17配体的超精细（hfi）和核四极（nqi）相互作用参数。氧代-O-17的各向同性hfi常数为6.5 MHz，远小于钼酶中赤道OH（2）配体170核的典型值（20-40 MHz）。170 nqi参数（e（2）qQ/h = 1.45MHz，eta近似为0）是首次获得的金属配合物中oxc，基团的参数。用准相对论密度泛函理论计算得到的氧代O-17配体的参数以及[（MoO）-O-17（SPh）（4）]（-）的其他磁共振参数与实验结果符合得很好。从DFT揭示的配合物的电子结构，它遵循的SOMO几乎完全是钼cl，和硫p，而氧代-O-17上的自旋密度是负的，由自旋极化机制确定。这项工作的结果将使在各种化学和生物系统中的氧代配体的直接实验鉴定。
K-a band ESEEM spectroscopy was used to determine the hyperfine (hfi) and nuclear quadrupole (nqi) interaction parameters for the oxo-O-17 ligand in [(MOO)-O-17(SPh)(4)](-), a spectroscopic model of the oxo-Mo(V) centers of enzymes. The isotropic hfi constant of 6.5 MHz found for the oxo-O-17 is much smaller than the values of similar to 20-40 MHz typical for the 170 nucleus of an equatorial OH(2) ligand in molybdenum enzymes. The 17 0 nqi parameter (e(2)qQ/h = 1.45 MHz, eta approximate to 0) is the first to be obtained for an oxc, group in a metal complex. The parameters of the oxo-O-17 ligand, as well as other magnetic resonance parameters of [(MoO)-O-17(SPh)(4)](-) predicted by quasi-relativistic DFT calculations, were in good agreement with those obtained in experiment. From the electronic structure of the complex revealed by DFT, it follows that the SOMO is almost entirely molybdenum cl, and sulfur p, while the spin density on the oxo-O-17 is negative, determined by spin polarization mechanisms. The results of this work will enable direct experimental identification of the oxo ligand in a variety of chemical and biological systems.