Vapor-Diffusion-Mediated Single Crystal-to-Single Crystal Transformation of a Discrete Dimeric Copper(II) Complex to a Discrete Tetrameric Copper(II) Complex

摘要

The symmetric dimeric complex [Cu(u_2-hep)(TFA)(H_2O)]_2 (1) has been synthesized from 2-(2-hydroxyethyl)pyridine (hep-H), trifluoroacetic acid (TFA-H), and copper acetate in a 95:5 (v/v) MeOH—H_2O mixture at 298 K. Each Cu~(II) ion in 1 is linked with two |ì_2-alcoholic oxygen atoms and one pyridine nitrogen atom of hep, and the other two coordination sites are occupied by the oxygen donors of TFA and H_20. At room temperature, the blue single crystals of 1 transform to the green single crystals of a tetrameric complex, [Cu_4(|ì_3-hep)_2(|ì_2-hep)_2(|ì_2-TFA)_2(TFA)_2] (2), in presence of alcoholic vapor. The facile single crystal-to-single crystal (SCSC) transformation of 1 to 2 is accompanied by the removal of coordinated H_2O molecules in 1 and concomitant formation of four new covalent bonds, two Cu-O(|ì_3-hep) and two Cu-0(|ì_2-TFA). The SCSC transformation of 1 to 2 is selective to the alcoholic vapor; the exposure of single crystals of 1 to heat or light or in vacuum has resulted in an immediate loss in crystallinity.