Hydrogen-bonding interactions, geometrical selectivity and spectroscopic properties of cobalt(III) complexes with unsymmetrical tridentate amine-amidato-phenolato type ligands
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- 作者：Ryoji Mitsuhashi ; mitsuhashi@s.okayama-u.ac.jp ; Takayoshi Suzuki ; suzuki@okayama-u.ac.jp ; Yukinari Sunatsuki ; Masaaki Kojima
- 关键词：Double hydrogen bonds ; Amine-amidato type ligand ; Geometrical isomers ; Diastereoselectivity ; Solvatochromism
- 刊名：Inorganica Chimica Acta
- 出版年：2013
- 出版时间：1 April, 2013
- 年：2013
- 卷：399
- 期：Complete
- 页码：131-137
- 全文大小：810 K
文摘
Four cobalt(III) complexes with the formula of [Co(Ln)2]? bearing tridentate amine-amidato-phenolato-type ligands (Ln: n = 1-4) were synthesized. All of the complexes were characterized by 1H NMR spectroscopy and X-ray analysis. The geometrical selectivity was found to depend on the flexibility of the amine-amidato chelate in combination with the planar 2-oxybenzamido 6-membered chelate; that is, the amine-amidato 5-membered chelate took the mer-type geometry, and the 6-membered chelate took the fac-type geometry. In most of the mer-type complexes, intermolecular double hydrogen bonds via amidato(O) and amino group were selectively formed between their enantiomeric pairs of mononuclear complexes. In the case of two chiral ligands {L22- = 2-amino-1-(2-oxybenzamido)propane; L32? = trans-1-amino-2-(2-oxybenzamido)cyclohexane}, [Co(L3)2]? showed diastereoselectivity while [Co(L2)2]? did not. Furthermore, PPh4[Co(L1)2] (L12? = 2-amino-1-(2-oxybenzamido)-2-methylpropane) showed an apparent solvatochromic behavior in several solvents. Although the molecular structures of [Co(L2 or L3)2]? are quite similar to that of [Co(L1)2]?, these complexes did not exhibit such a solvatochromic behavior.