diborane antifluorite Clb RbCl adamantane GeCl2 CaSO3 monomeric crystalline S4N4 dinitrogen NbCl5 jerrygibbsite Zintl solid Ni2 hydrates digestate oligomeric hexafluoroplatinate nonpolar porosities FMOC structure Cyclin hydrate nonflammable trigonal allotropes polymeric aaa complexor