Group 6 carbon monoxide-releasing metal complexes with biologically-compatible leaving groups.
Group 6 carbon monoxide-releasing metal complexes with biologically-compatible leaving groups.
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DOI：
10.1021/ic101230j
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发表时间：
2010-10
影响因子：
4.6
通讯作者：
Wei-Qiang Zhang;A. Whitwood;I. Fairlamb;Jason M. Lynam
中科院分区：
文献类型：
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作者：
Wei-Qiang Zhang;A. Whitwood;I. Fairlamb;Jason M. Lynam
报道了一系列基于M（CO）（5）骨架（M = Cr，Mo，W）的CO释放分子（CO-RM）。金属羰基阴离子[MCl（CO）（5）]（-）被证明是含有氨基酯基的第6族五羰基络合物，即[M（CO）（5）（NH（2）CH{R}CO（2）R '）]的高度通用的前体。通过单晶X-射线衍射确定了五个配合物的结构，包括基于（R）和（S）-丙氨酸的对映体对。这些物种表现出快速CO释放，如肌红蛋白为基础的测定所示。释放速率受所用金属和氨基酯的性质影响。一个机制的研究表明，一个共同的中间体形成相应的损失的氨基酯从金属。此外，基于Fischer型卡宾络合物，制备了另外一系列潜在的CO-RM，其含有氨基酯或氨基酸。氨基酯和氨基酸通过在卡宾碳原子处的亲核取代反应被引入到金属的配位层中。通过NH（2）CH（2）CO（2）Et在[Cr（CO）（5）（CH 2C {OMe}-C CH 2CPh）]三键上的Michael加成反应，得到了晶体学上表征的[Cr（CO）（5）（CH 2C {OMe}-（Z）-CH CH 2C {Ph}NHCH（2）CO（2）Et）].从卡宾络合物的CO-释放速率主要取决于连接到卡宾中心的特定杂原子。在硫和甲氧基稳定的卡宾的情况下观察到快速CO释放，而在氨基取代的卡宾的情况下，释放慢得多。这可能与卡宾碳原子上的亲电性有关。
A series of carbon monoxide-releasing molecules (CO-RMs) based on the M(CO)(5) framework (M = Cr, Mo, W) is reported. The metal carbonyl anions [MCl(CO)(5)](-) are shown to be highly versatile precursors to Group 6 pentacarbonyl complexes containing amino-ester groups, namely, [M(CO)(5)(NH(2)CH{R}CO(2)R')]. The structures of five of the complexes, including an enantiomeric pair based on (R) and (S)-alanine, were determined by single crystal X-ray diffraction. These species exhibit rapid CO-release, as shown by a myoglobin-based assay. The rate of release is affected by the nature of both the metal and the amino-ester employed. A mechanistic study shows that a common intermediate is formed corresponding to loss of the amino-ester from the metal. In addition, a further series of potential CO-RMs have been prepared based on Fischer-type carbenes complexes, which contain either amino esters or amino acids. The amino esters and amino acids are introduced into the coordination sphere of the metal by a nucleophilic substitution reaction at the carbene carbon atom. The Michael addition of NH(2)CH(2)CO(2)Et across the triple bond in [Cr(CO)(5)(═C{OMe}-C≡CPh)] affords crystallographically characterized [Cr(CO)(5)(═C{OMe}-(Z)-CH═C{Ph}NHCH(2)CO(2)Et)]. The rate of CO-release from the carbene complexes depends primarily on the specific heteroatom connected to the carbene center. Rapid CO-release is observed in the case of sulfur- and methoxy-stabilized carbenes whereas in the case of amino-substituted carbenes, release is far more sluggish. This may be correlated with the electrophilic character at the carbene carbon atom.