ERROR opening https://cactus.nci.nih.gov/chemical/structure/C%5BSi%5D%28C%29%28C%29%5BSi%5D%28C%29%28C%29C/file?format=sdf&get3d=True -- C%5BSi%5D%28C%29%28C%29%5BSi%5D%28C%29%28C%29C could not be loaded.