Copper(I) and copper(II) complexes possessing cross-linked imidazole-phenol ligands:: Structures and dioxygen reactivity
Copper(I) and copper(II) complexes possessing cross-linked imidazole-phenol ligands:: Structures and dioxygen reactivity
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DOI：
10.1021/ja034263f
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发表时间：
2003-05-21
影响因子：
15
通讯作者：
Karlin, KD
中科院分区：
文献类型：
--
作者：
Kamaraj, K;Kim, E;Karlin, KD
O2到H2O的催化还原，以及与膜质子转移的耦合，发生在细胞色素氧化酶的异双核血红素a3− CuB活性位点。其中一个CuBligated组氨酸与相邻的酪氨酸（C-N键;酪氨酸C6和组氨酸ε-氮）交联，并且该交联的His-Tyr部分的质子残基被提议作为电子和质子供体参与催化分子氧还原事件。为了深入了解这样的部分的化学，我们已经合成和表征了四齿和三齿吡啶基烷基胺螯合配体{LN 4 OR和LN 3 OR（R = H或Me）}，其包括咪唑-苯酚（或苯甲醚）交联和它们的铜（I/II）络合物。[CuI（LN 4 OH）]B（C6 F5）4（1）在-80 °C的THF中与分子氧反应，形成不稳定的反式-μ-1，2-过氧二铜（II）络合物，随后转化为二聚铜（II）-酚盐络合物[{Cu（LN 4 O-）}2]（B（C6 F5）4）2（5a）。类似物[CuI（LN 4 OMe）]B（C6 F5）4（3）在−80 °C的四氢呋喃中可逆地结合双氧。[CuI（LN 3OH）] ClO 4（2）与O2在CH 2Cl 2中反应的停流动力学表明稳定形成紫色二聚体产物[{Cu（LN 3 O-）}2]（ClO 4）2（5 b），在−40至+20 °C的温度范围内进行了分析，ΔH = −9.6（6）kJ mol-1，ΔS ε = −168（2）J mol-1K-1（k（-40 ° C）= 1.05（4）× 106andk（+20 ° C）= 4.6（2）× 105M-2s-1）。本文报道了[Cu Ⅱ（LN_3OH）（MeOH）（OClO_3 ~-）]（ClO_4）（4）、5a和5的X射线晶体结构。
Catalytic reduction of O2to H2O, and coupling to membrane proton translocation, occurs at the heterobinuclear heme a3−CuBactive site of cytochromecoxidase. One of the CuBligated histidines is cross-linked to a neighboring tyrosine (C−N bond; tyrosine C6 and histidine ε-nitrogen), and the protic residue of this cross-linked His-Tyr moiety is proposed to participate as both an electron and a proton donor in the catalytic dioxygen reduction event. To provide insight into the chemistry of such a moiety, we have synthesized and characterized tetra- and tridentate pyridylalkylamine chelate ligands {LN4OR and LN3OR (R = H or Me)}, which include an imidazole-phenol (or anisole) cross-link and their copper(I/II) complexes. [CuI(LN4OH)]B(C6F5)4(1) reacts with dioxygen at −80 °C in THF, forming an unstabletrans-μ-1,2-peroxodicopper(II)complex, which subsequently converts to a dimeric copper(II)-phenolate complex [{Cu(LN4O-)}2](B(C6F5)4)2(5a). The close analogue [CuI(LN4OMe)]B(C6F5)4(3) binds dioxygen reversibly at −80 °C in tetrahydrofuran. Stopped-flow kinetics of the reaction [CuI(LN3OH)]ClO4(2) with O2in CH2Cl2indicate a steady formation of the purple dimeric product [{Cu(LN3O-)}2](ClO4)2(5b), which has been analyzed in the temperature range from −40 to +20 °C, ΔH⧧= −9.6 (6) kJ mol-1, ΔS⧧= −168 (2) J mol-1K-1(k(-40°C)= 1.05(4) × 106andk(+20°C)= 4.6(2) × 105M-2s-1). The X-ray crystal structures of1, [CuII(LN3OH)(MeOH)(OClO3-)](ClO4) (4),5a, and5bare reported.