Postgraduate Department of Chemistry, Panskura Banamali College, Panskura RS, Purba Medinipur, West Bengal 721 152, India.
Dalton Trans. 2014 Apr 14;43(14):5443-52. doi: 10.1039/c3dt52597j.
Two new azide bound cobalt(III) complexes, [Co(L(1))(N3)3] (fac-1) and [Co(L(2))(N3)3] (mer-2), where L(1) is bis(2-pyridylmethyl)amine and L(2) is (2-pyridylmethyl)(2-pyridylethyl)amine, derived from tridentate reduced Schiff-base ligands have been reported. Interestingly, a methylene bridge regulated preferential coordination mode of ligands is noticed in their crystal structures: it is found in a facial arrangement in fac-1 and has a meridional disposition in mer-2. Both complexes show phenoxazinone synthase-like activity and the role of the structural factor on the catalytic activity is also explored. Moreover, the easily reducible cobalt(III) center in mer-2 favors the oxidation of o-aminophenol. The ESI-MS positive spectra together with UV-vis spectroscopy clearly suggest the formation of a catalyst-substrate adduct by substitution of the coordinated azide ions in the catalytic cycle.
报道了两个新型叠氮键合的钴(III)配合物，[Co(L(1))(N3)3]（fac-1）和[Co(L(2))(N3)3]（mer-2），其中 L(1)是双(2-吡啶甲基)胺，L(2)是(2-吡啶甲基)(2-吡啶基乙基)胺，它们来源于三齿还原席夫碱配体。有趣的是，在它们的晶体结构中注意到了亚甲基桥调节配体优先配位模式：在 fac-1 中呈面式排列，在 mer-2 中呈经式排列。这两个配合物都表现出苯并噁嗪酮合酶样活性，并探讨了结构因素对催化活性的作用。此外，mer-2 中易于还原的钴(III)中心有利于邻氨基酚的氧化。ESI-MS 正谱和紫外可见光谱清楚地表明，在催化循环中，取代配位的叠氮离子形成了催化剂-底物加合物。
