ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/6C2H4O2.Ca.2Mg/c6*1-2(3)4;;;/h6*1H3,(H,3,4);;;/q;;;;;;3* 2/p-6/file?format=sdf&get3d=True  -- InChI=1S/6C2H4O2.Ca.2Mg/c6*1-2(3)4;;;/h6*1H3,(H,3,4);;;/q;;;;;;3* 2/p-6 could not be loaded.