Supramolecular assemblies of Cu(I) and Cu(II) pyrazine based complexes

Abstract

Istražene su reakcije i ispitani uvjeti priprave novih kompleksnih spojeva bakrovog(II) klorida i bakrovog(II) bromida s klorpirazinom (Cl−pz), brompirazinom (Br−pz) i jodpirazinom (I−pz). Pripravljeni su sljedeći spojevi [CuCl2(Cl‒pz)2] (1), [CuCl2(Br‒pz)2] (2), [CuCl2(I‒pz)2] (3a), [CuCl2(I‒pz)2] (3b), [CuBr2(Cl‒pz)2] (4), [CuBr2(Br‒pz)2] (5), [CuBr(Br‒pz)]n (6), [CuBr2(I‒pz)2] (7) i [CuBr(I‒pz)]n (8). Spojevi su okarakterizirani kemijskom analizom, infracrvenom spektroskopijom, termogravimetrijskom analizom i difrakcijom rentgenskog zračenja na praškastom uzorku. Spojevima 3b, 6, 7 i 8 je rentgenskom strukturnom analizom određena kristalna i molekulska struktura. Ustanovljeno je da bakar(II) s halogenpirazinima daje jednostavne monomerne molekule u kojima je atom bakra kvadratno-planarno koordiniran, dok bakar(I) polimerizira te nastaju 2D-koordinacijski polimeri. Neovisno o dimenzionalnosti gradbenih jedinica do supramolekulskog udruživanja dolazi preko istog tipa halogenskih veza, osim kod spoja 3b gdje je pronađen drugačiji supramolekulski motiv.The reaction conditions of copper(II) chloride and copper(II) bromide with chloropyrazine, bromopyrazine and iodopyrazine were investigated. The following complexes were prepared: [CuCl2(Cl‒pz)2] (1), [CuCl2(Br‒pz)2] (2), [CuCl2(I‒pz)2] (3a), [CuCl2(I‒pz)2] (3b), [CuBr2(Cl‒pz)2] (4), [CuBr2(Br‒pz)2] (5), [CuBr(Br‒pz)]n (6), [CuBr2(I‒pz)2] (7) i [CuBr(I‒pz)]n (8). Compounds were characterized by chemical analysis, infrared spectroscopy, thermogravimetric analysis and X-ray powder diffraction. Compounds 3a, 6, 7 i 8 were structurally characterized by single crystal X-ray diffraction method. Structural investigation revealed that Cu(II) with halopyrazines form simple monomeric square-planar building units, while Cu(I) polymerizes and gives 2D-layered building blocks. Regardless of their dimensionality, the building units are assembled into supramolecular architectures via the same type of halogen-bonding. Only in the case of 3b a different supramolecular motif was found