Crystal structure of [2,2′-((((ethane-1,2-diylbis(oxy-κ2O,O′))bis(2,1-phenylene))bis(azanylylidene-κ2N,N′))bis(methanylylidene))diphenolato-κ2O′′,O′′′]zinc(II), C28H22N2O4Zn