Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints Pères, 75270 Paris Cedex 06, France.
Inorg Chem. 2012 Sep 3;51(17):9350-6. doi: 10.1021/ic301090t. Epub 2012 Aug 20.
Six Co(III) complexes based on unsubstituted or substituted TPA ligands (where TPA is tris(2-pyridylmethyl)amine) and acetohydroxamic acid (A), N-methyl-acetohydroxamic acid (B), or N-hydroxy-pyridinone (C) were prepared and characterized by mass spectrometry, elemental analysis, and electrochemistry: Co(III)(TPA)(A-2H) (1a), Co(III)((4-Cl(2))TPA)(A-2H) (2a), Co(III)((6-Piva)TPA)(A-2H) (3a), Co(III)((4-Piva)TPA)(A-2H) (4a) and Co(III)(TPA)(B-H)(2) (1b), and Co(III)(TPA)(C-H)(2) (1c). Complexes 1a-c and 3a were analyzed by (1)H NMR, using 2D ((1)H, (1)H) COSY and 2D ((1)H, (13)C) HMBC and HSQC, and shown to exist as a mixture of two geometric isomers based on whether the hydroxamic oxygen was trans to a pyridine nitrogen or to the tertiary amine nitrogen. Complex 3a exists as a single isomer that was crystallized. Its crystal structure revealed the presence of an H-bond between the pivaloylamide and the hydroximate oxygen. Complexes 1a, 2a, and 4a are irreversibly reduced beyond -900 mV versus SCE, while complexes 1b and 1c are reduced at less negative values of -330 and -190 mV, respectively. The H-bond in 3a increased the redox potential up to -720 mV. Reaction of complex 1a with L-cysteine methyl ester CysOMe was monitored by (1)H NMR and UV-vis at 2 mM and 0.2 mM in an aqueous buffered solution at pH 7.5. Complex 1a was successively converted into an intermediate Co(III)(TPA)(CysOMe-H), 1d, by exchange of the hydroximate with the cysteinate ligand, and further into Co(III)(CysOMe-H)(3), 5. An authentic sample of 1d was prepared and thoroughly characterized. A detailed (1)H NMR analysis showed there was only one isomer, in which the thiolate was trans to the tertiary amine nitrogen.
基于未取代或取代的 TPA 配体（TPA 是三（2-吡啶甲基）胺）和乙酰羟肟酸（A）、N-甲基-乙酰羟肟酸（B）或 N-羟基吡啶酮（C）的六个 Co(III) 配合物被制备并通过质谱、元素分析和电化学进行了表征：Co(III)(TPA)(A-2H) (1a)、Co(III)((4-Cl(2))TPA)(A-2H) (2a)、Co(III)((6-Piva)TPA)(A-2H) (3a)、Co(III)((4-Piva)TPA)(A-2H) (4a) 和 Co(III)(TPA)(B-H)(2) (1b) 和 Co(III)(TPA)(C-H)(2) (1c)。配合物 1a-c 和 3a 通过 (1)H NMR 进行了分析，使用二维 ((1)H, (1)H) COSY 和二维 ((1)H, (13)C) HMBC 和 HSQC，并基于肟氧是否与吡啶氮或叔胺氮反式存在来证明其为两种几何异构体的混合物。3a 以单一异构体存在并结晶。其晶体结构显示出 pivaloylamide 和 hydroximate 氧之间存在氢键。复合物 1a、2a 和 4a 在超过 -900 mV 相对于 SCE 不可逆还原，而复合物 1b 和 1c 在分别为 -330 和 -190 mV 的较负值下还原。氢键使 3a 的氧化还原电位增加到 -720 mV。在 pH 7.5 的水性缓冲溶液中，在 2 mM 和 0.2 mM 下，通过 (1)H NMR 和 UV-vis 监测配合物 1a 与 L-半胱氨酸甲酯 CysOMe 的反应。配合物 1a 被成功地转化为中间体 Co(III)(TPA)(CysOMe-H)，1d，通过肟与半胱氨酸配体的交换，进一步转化为 Co(III)(CysOMe-H)(3)，5。制备了 1d 的一个纯样品并进行了彻底的表征。详细的 (1)H NMR 分析表明只有一种异构体，其中硫醇盐与叔胺氮反式。
