Kinetics and mechanisms of catalytic oxygen atom transfer with oxorhenium(V) oxazoline complexes
Kinetics and mechanisms of catalytic oxygen atom transfer with oxorhenium(V) oxazoline complexes
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DOI：
10.1021/ic000917z
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发表时间：
2001-04-23
影响因子：
4.6
通讯作者：
Abu-Omar, MM
中科院分区：
文献类型：
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作者：
Arias, J;Newlands, CR;Abu-Omar, MM
铼(V)单氧配合物 (hoz)(2)Re(O)Cl (1) 和 [(hoz)(2)Re(O)(OH2)] [OTf] (2) 已合成并完全表征（hoz = 2-(2'-羟基苯基)-2-恶唑啉）。已解出2小时的单晶X射线结构：空间群=P(1)在bar上，a=13.61(2)埃，b=14.76(2)埃，c=11.571(14)埃，α=93.69(4)度，β=99.43(4)度，gamma= 108.44(4)度，Z=4；结构被细化为最终残差 R = 0.0455 和 R-w = 0.1055。 1和2催化氧原子从芳基亚砜转移到烷基硫醚以及亚砜之间的氧加扰生成砜和硫化物。由于铼上存在配位位点，2 具有优异的催化活性。该催化剂的活性形式是二氧铼(VII)中间体[Re(O)(2)(hoz)(2)](+) (3)。在硫化物存在下，3 迅速还原为 [Re(O)(hoz)(2)](+)，亚砜作为唯一的有机产物。过渡态对电子影响非常敏感。 4 对位取代茴香硫醚衍生物的哈米特相关图给出的反应常数 p 为 -4.6 +/- 0.4，与铼的亲电子氧转移一致。高浓度硫化物会抑制催化反应。确定了几种硫化物与复合物 3（抑制原因）K-2 (L mol(-1)) 结合的硫化物的平衡常数：Me2S (22 +/- 3)、Et2S (14 +/- 2)。和(Bu2S)-Bu-t-S-t(8+/-2)。从溶液中的平衡测量获得的热力学数据表明，烷基亚砜中的 S=O 键比芳基亚砜中的更强。 3中的Re=O键强度估计约为20 kcal mol(-1)。讨论了配合物 3 的高活性和氧亲电子性，并将其与类似的钼系统联系起来。
The rhenium(V) monooxo complexes (hoz)(2)Re(O)Cl (1) and [(hoz)(2)Re(O)(OH2)] [OTf] (2) have been synthesized and fully characterized (hoz = 2-(2 ' -hydroxyphenyl)-2-oxazoline). A single-crystal X-ray structure of 2 h as been solved: space group = P (1) over bar, a = 13.61(2) Angstrom, b = 14.76(2) Angstrom, c = 11.571(14) Angstrom, alpha = 93.69(4)degrees, beta = 99.43(4)degrees, gamma = 108.44(4)degrees, Z = 4; the structure was refined to final residuals R = 0.0455 and R-w = 0.1055. 1 and 2 catalyze oxygen atom transfer from aryl sulfoxides to alkyl sulfides and oxygen-scrambling between sulfoxides to yield sulfone and sulfide. Superior catalytic activity has been observed for 2 due to the availability of a coordination site on the rhenium. The active form of the catalyst is a dioxo rhenium(VII) intermediate, [Re(O)(2)(hoz)(2)](+) (3). In the presence of sulfide, 3 is rapidly reduced to [Re(O)(hoz)(2)](+) with sulfoxide as the sole organic product. The transition state is very sensitive to electronic influences. 4 Hammett correlation plot with para-substituted thioanisole derivatives gave a reaction constant p of -4.6 +/- 0.4, in agreement with an electrophilic oxygen transfer from rhenium. The catalytic reaction features inhibition by sulfides at high concentrations. The equilibrium constants for sulfide binding to complex 3 (cause of inhibition), K-2 (L mol(-1)), were determined for a few sulfides: Me2S (22 +/- 3), Et2S (14 +/- 2). and (Bu2S)-Bu-t-S-t (8 +/- 2). Thermodynamic data, obtained from equilibrium measurements in solution, show that the S=O bond in alkyl sulfoxides is stronger than in aryl sulfoxides. The Re=O bond strength in 3 was estimated to be about 20 kcal mol(-1). The high activity and oxygen electrophilicity of complex 3 are discussed and related to analogous molybdenum systems.