Cooperative H-bonds, π···π and anion···π interactions as driving forces in the construction of novel Cu(II) bis(imidazol-2-yl) supramolecular 3D frameworks

Abstract Two new Cu(II) complexes with bis(2-imidazolyl) based ligands, with the formula [Cu(BIM) 2 (SCN) 2 ]·2H 2 O (BIM = bis(2-imidazol-2-yl)methane) and [Cu(HBIMAM) 2 (OH 2 ) 2 ](BF 4 ) 4 ⋅2H 2 O (BIMAM = bis(2-imidazol-2-yl) methylaminomethane) have been synthesized and characterized. Both compounds contain mononuclear entities as molecular building blocks (MBBs); neutral [Cu(BIM) 2 (SCN) 2 ] in compound 1 and cationic [Cu(HBIMAM) 2 (OH 2 ) 2 ] 4+ in compound 2 . The coordination around the metal atoms shows a tetragonally-elongated octahedral geometry (CuN 4 S 2 and CuN 4 O 2 chromophores). The Q-band EPR spectra of both compounds are indicative of an essentially d x2–y2 ground state for copper(II) ions. The analysis of the crystal structures of both compounds shows a cooperative relationship between conventional hydrogen bonds and other non-covalent interactions. Thus, in compound 1 concerted π···π interactions are the driving force in the construction of one-dimensional frameworks, which are connected through H-bonds to give 3D structure. On the other hand, in compound 2 , cooperative X-H ···F (X = N, O) H-bonds and anion···π interactions control the arrangement of the supramolecular 3D framework.