Börzel Heidi, Comba Peter, Hagen Karl S, Kerscher Marion, Pritzkow Hans, Schatz Markus, Schindler Siegfried, Walter Olaf
Anorganisch-Chemisches Institut der Universität Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany.
Inorg Chem. 2002 Oct 21;41(21):5440-52. doi: 10.1021/ic011114u.
Copper(I) and copper(II) complexes of two mononucleating and four dinucleating tetradentate ligands with a bispidine backbone (2,4-substituted (2-pyridyl or 4-methyl-2-pyridyl) 3,7-diazabicyclo[3.3.1]nonanone) have been prepared and analyzed structurally, spectroscopically, and electrochemically. The structures of the copper chromophores are square pyramidal, except for two copper(I) compounds which are four-coordinate with one noncoordinated pyridine. The other copper(I) structures have the two pyridine donors, the co-ligand (NCCH(3)), and one of the tertiary amines (N3) in-plane with the copper center and the other amine (N7) coordinated axially (Cu-N3 > Cu-N7, approximately 2.25 A vs 2.20 A). The copper(II) compounds with pyridine donors have a similar structure, but the axial amine has a weaker bond to the copper(II) center (Cu-N3 < Cu-N7, approximately 2.03 A vs 2.30 A). The structures with methylated pyridine donors are also square pyramidal with the co-ligands (Cl(-) or NCCH(3)) in-plane. With NCCH(3) the same structural type as for the other copper(II) complexes is observed, and with the bulkier Cl(-) the co-ligand is trans to N7, leading to a square pyramidal structure with the pyridine donors rotated out of the basal plane and only a small difference between axial and in-plane amines (2.15, 2.12 A). These structural differences, enforced by the rigid bispidine backbone, lead to large variations in spectroscopic and electrochemical properties and reactivities. Oxygenation of the copper(I) complexes with pyridine-substituted bispidine ligands leads to relatively stable mu-peroxo-dicopper(II) complexes; with a preorganization of the dicopper chromophores, by linking the two donor sets, these peroxo compounds are stable at room temperature for up to 1 h. The stabilization of the peroxo complexes is to a large extent attributed to the square pyramidal coordination geometry with the substrate bound in the basal plane, a structural motif enforced by the rigid bispidine backbone. The stabilities and structural properties are also seen to correlate with the spectroscopic (UV-vis and Raman) and electrochemical properties.
已制备并通过结构、光谱和电化学方法分析了两种单齿和四种双齿四齿配体与双吡啶骨架（2,4-取代（2-吡啶基或4-甲基-2-吡啶基）3,7-二氮杂双环[3.3.1]壬酮）形成的铜（I）和铜（II）配合物。铜发色团的结构为四方锥型，但有两种铜（I）化合物为四配位，含有一个未配位的吡啶。其他铜（I）结构中，两个吡啶供体、共配体（NCCH(3)）和一个叔胺（N3）与铜中心共面，另一个胺（N7）轴向配位（Cu-N3 > Cu-N7，约2.25 Å对2.20 Å）。含吡啶供体的铜（II）化合物结构相似，但轴向胺与铜（II）中心的键较弱（Cu-N3 < Cu-N7，约2.03 Å对2.30 Å）。含甲基化吡啶供体的结构也是四方锥型，共配体（Cl(-)或NCCH(3)）在平面内。对于NCCH(3)，观察到与其他铜（II）配合物相同的结构类型，而对于体积较大的Cl(-)，共配体与N7反位，导致四方锥型结构，吡啶供体旋转出基面，轴向胺和平面内胺之间只有很小差异（2.15、2.12 Å）。由刚性双吡啶骨架导致的这些结构差异，引起光谱、电化学性质和反应活性的巨大变化。用吡啶取代的双吡啶配体对铜（I）配合物进行氧化，得到相对稳定的μ-过氧-二铜（II）配合物；通过连接两个供体基团对二铜发色团进行预组织，这些过氧化合物在室温下可稳定长达1小时。过氧配合物的稳定性在很大程度上归因于四方锥型配位几何结构，底物结合在基面，这是由刚性双吡啶骨架强制形成的结构基序。稳定性和结构性质也与光谱（紫外可见和拉曼）及电化学性质相关。
