Solvent Control Over Structural Diversity of Two Copper (II) Complexes Based on Polyaromatic Acid Ligand

Abstract

A new bipod polyaromatic acid ligand H2bcm (H2bcm = {2, 4-bis [(2′-carboxyphenoxy) methyl]-1,3,5-trimethylbenzene}) is prepared and its two novel binuclear coordination compounds, [Cu2(bcm)2(CH3OH)2]·2CH3OH (1) and [Cu2(bcm)2(CH3CH2OH)2]·2CH3CH2OH (2), have been synthesized with copper acetate and H2bcm ligand in methanol solvent and ethanol solvent respectively, and characterized by the element analysis, IR, TGA and single crystal X-ray diffraction. The results of structural analysis indicate that 1 crystallizes in the triclinic system with space group P1, while 2 crystallizes in the monoclinic system with space group P21 /c. Furthermore, 1 adopts μ 2 -COO− and syn–syn coordination mode with Cu (II)···Cu (II) separation of 2.5868(11) A and forms 1D zigzag chain structure by O···O interactions. The coordination of 2 is similar to that of 1 except that ethanol molecules are coordinated instead of methanol molecules with Cu (II)···Cu (II) separation of 2.5973(13) A. Two-dimensional network structures of 1 and 2 are formed through π–π interactions. A new bipod polyaromatic acid ligand H2bcm (H2bcm= {2, 4-bis [(2′-carboxyphenoxy)methyl]-1,3,5-trimethylbenzene}) is prepared and its two novel binuclear coordination compounds, [Cu2(bcm)2(CH3OH)2]·2CH3OH (1) and [Cu2(bcm)2(CH3CH2OH)2]·2CH3CH2OH (2), have been synthesized with copper acetate and H2bcm ligand in methanol solvent and ethanol solvent respectively, and characterized through single-crystal X-ray diffraction. Compound 1 crystallized in the space group P1, while 2 crystallizes in the monoclinic system with space group P21 /c. Since the only difference in the synthetic condition between complexes 1 and 2 is that of the reaction solvent, resulting in the structure of complex 1 being significantly distinct from that of complex 2. It is clear that reaction solvent plays a key role in controlling the structure of the complexes.