Crystal structure of catena-poly[hemi[1,3-bis(2,6-diisopropylphenyl)imidazolium] [[μ3-acetato-κ3 O:O:O′-tri-μ2-acetato-κ6 O:O′-dicopper(II)(Cu—Cu)]-μ-chlorido] dichloromethane sesquisolvate]