Structural and electronic characterization of multi-electron reduced naphthalene (BIAN) cobaloximes.
Structural and electronic characterization of multi-electron reduced naphthalene (BIAN) cobaloximes.
复制标题
多电子还原萘 (BIAN) 钴肟的结构和电子表征。
作者：
Owen M. Williams;A. Cowley;Michael J. Rose
本文报道了以双(亚氨基)庚(Bian)为配体的钴肟的合成和表征。本文报道了[Co(AqdBF_2)_2(MeCN)_2]()、[Co(AqdBF_2)(MeCN)_2](-)()和[Co(AqdBF_2)_2(MeCN)_2](2-)(，)系列中三电子还原配合物[Co(AqdBF_2)_2(MeCN)_2](3-)()的X-射线晶体结构和波谱，并用(1)H-核磁共振进行了表征。X-射线晶体结构表明存在一个6配位的Co(II)物种()、一个5配位的Co(I)物种()和一个4配位的配合物(，)。在络合物的情况下，来自单晶电子顺磁共振谱(g‖=2.017，g⊥=1.987；<；10G线宽)的证据结合密度泛函计算表明，电子顺磁共振信号来自离域的基于配体的未配对自旋。由密度泛函理论计算得到的前线轨道支持光谱观察到的电子归属。溶剂同系物[Co(AqdBF2)2(DMF)2]在DMF溶液中的阴极循环伏安曲线在-1.0、-1.5和-2.0V与Fc/Fc(+)附近出现三个可逆氧化还原事件。循环伏安在第三个氧化还原峰附近观察到质子的催化还原。与其他钴肟(ECAT=-1.0V)相比，催化起始时间的延迟是由于存在一系列共振稳定的中间体。
Reported here are the syntheses and characterization of cobaloximes that feature a bis(imino)acenaphthene (BIAN) appended ligand. The X-ray crystal structures and spectroscopy ((1)H NMR or EPR) of the complexes within the series [Co(aqdBF2)2(MeCN)2] (), [Co(aqdBF2)(MeCN)2](-) () and [Co(aqdBF2)2(MeCN)2](2-) (, ) are reported and the 3-electron reduced complex [Co(aqdBF2)2(MeCN)2](3-) () has been prepared in situ and characterized by (1)H NMR spectroscopy. The X-ray crystal structures revealed the presence of a 6-coordinate Co(II) species (), a 5-coordinate Co(I) species (), and a 4-coordinate complex (, ). In the case of complex , evidence from single crystal EPR spectroscopy (g‖ = 2.017, g⊥ = 1.987; <10 G linewidths) in conjunction with DFT calculations indicate that the EPR signal originates from a delocalized ligand-based unpaired spin. The frontier orbitals obtained from DFT calculations on , , , & support the electronic assignments that were observed spectroscopically. The cathodic cyclic voltammogram (CV) of the solvato congener in DMF solution, namely [Co(aqdBF2)2(DMF)2], exhibits three reversible redox events near -1.0, -1.5 and -2.0 V vs. Fc/Fc(+). Catalytic proton reduction was observed by CV near the third redox peak. Compared with other cobaloximes (Ecat = -1.0 V), the delay of catalytic onset arises from the existence of a series of resonance-stabilized intermediates.
影响因子：
3.3
作者：
Niklas, Jens;Mardis, Kristy L.;Rakhimov, Rakhim R.;Mulfort, Karen L.;Tiede, David M.;Poluektov, Oleg G.
通讯作者：
Poluektov, Oleg G.
DOI：
10.1073/pnas.1118329109
发表时间：
2012-07
期刊：
Proceedings of the National Academy of Sciences
影响因子：
--
作者：
Carolyn N. Valdez;J. Dempsey;B. Brunschwig;J. Winkler;H. Gray
通讯作者：
Carolyn N. Valdez;J. Dempsey;B. Brunschwig;J. Winkler;H. Gray