Matsumoto Takahiro, Ohkubo Kei, Honda Kaoru, Yazawa Akiko, Furutachi Hideki, Fujinami Shuhei, Fukuzumi Shunichi, Suzuki Masatatsu
Department of Chemistry, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
J Am Chem Soc. 2009 Jul 8;131(26):9258-67. doi: 10.1021/ja809822c.
A (mu-eta(2):eta(2)-peroxo)dicopper(II) complex, Cu(2)(H-L)(O(2)) (1-O(2)), supported by the dinucleating ligand 1,3-bis[bis(6-methyl-2-pyridylmethyl)aminomethyl]benzene (H-L) is capable of initiating C-H bond activation of a variety of external aliphatic substrates (SH(n)): 10-methyl-9,10-dihydroacridine (AcrH(2)), 1,4-cyclohexadiene (1,4-CHD), 9,10-dihydroanthracene (9,10-DHA), fluorene, tetralin, toluene, and tetrahydrofuran (THF), which have C-H bond dissociation energies (BDEs) ranging from approximately 75 kcal mol(-1) for 1,4-CHD to approximately 92 kcal mol(-1) for THF. Oxidation of SH(n) afforded a variety of oxidation products, such as dehydrogenation products (SH((n-2))), hydroxylated and further-oxidized products (SH((n-1))OH and SH((n-2))=O), dimers formed by coupling between substrates (H((n-1))S-SH((n-1))) and between substrate and H-L (H-L-SH((n-1))). Kinetic studies of the oxidation of the substrates initiated by 1-O(2) in acetone at -70 degrees C revealed that there is a linear correlation between the logarithms of the rate constants for oxidation of the C-H bonds of the substrates and their BDEs, except for THF. The combination of this correlation and the relatively large deuterium kinetic isotope effects (KIEs), k(2)(H)/k(2)(D) (13 for 9,10-DHA, approximately > 29 for toluene, and approximately 34 for THF at -70 degrees C and approximately 9 for AcrH(2) at -94 degrees C) indicates that H-atom transfer (HAT) from SH(n) (SD(n)) is the rate-determining step. Kinetic studies of the oxidation of SH(n) by cumylperoxyl radical showed a correlation similar to that observed for 1-O(2), indicating that the reactivity of 1-O(2) is similar to that of cumylperoxyl radical. Thus, 1-O(2) is capable of initiating a wide range of oxidation reactions, including oxidation of aliphatic C-H bonds having BDEs from approximately 75 to approximately 92 kcal mol(-1), hydroxylation of the m-xylyl linker of H-L, and epoxidation of styrene (Matsumoto, T.; et al. J. Am. Chem. Soc. 2006, 128, 3874).
由双核配体1,3 - 双[双(6 - 甲基 - 2 - 吡啶甲基)氨甲基]苯（H - L）支撑的A（μ - η(2):η(2) - 过氧）二铜（II）配合物Cu(2)(H - L)(O(2))（1 - O(2)）能够引发多种外部脂肪族底物（SH(n)）的C - H键活化：10 - 甲基 - 9,10 - 二氢吖啶（AcrH(2)）、1,4 - 环己二烯（1,4 - CHD）、9,10 - 二氢蒽（9,10 - DHA）、芴、四氢萘、甲苯和四氢呋喃（THF），这些底物的C - H键离解能（BDEs）范围从1,4 - CHD的约75 kcal mol(-1)到THF的约92 kcal mol(-1)。SH(n)的氧化产生了多种氧化产物，如脱氢产物（SH((n - 2))）、羟基化及进一步氧化的产物（SH((n - 1))OH和SH((n - 2)) = O）、底物之间（H((n - 1))S - SH((n - 1))）以及底物与H - L之间（H - L - SH((n - 1))）偶联形成的二聚体。在 - 70℃下于丙酮中对1 - O(2)引发的底物氧化进行动力学研究表明，除THF外，底物C - H键氧化速率常数的对数与其BDEs之间存在线性相关性。这种相关性与相对较大的氘动力学同位素效应（KIEs）相结合，k(2)(H)/k(2)(D)（ - 70℃下9,10 - DHA为13，甲苯约＞29，THF约为34； - 94℃下AcrH(2)约为9）表明从SH(n)（SD(n)）的氢原子转移（HAT）是速率决定步骤。对SH(n)被枯基过氧自由基氧化的动力学研究显示出与1 - O(2)观察到的类似相关性，表明1 - O(2)的反应性与枯基过氧自由基相似。因此，1 - O(2)能够引发广泛的氧化反应，包括BDEs约为75至约92 kcal mol(-1)的脂肪族C - H键的氧化、H - L的间二甲苯连接基的羟基化以及苯乙烯的环氧化（松本，T.；等人，《美国化学会志》2006年，128卷，3874页）。
