Properties of water by the IUPAC as being unsuitable for this purpose, since it is already the name of a cyclic ether also known as tetrahydropyran. The simplest systematic name of water is "hydrogen oxide". This is analogous to related compounds such as hydrogen peroxide, hydrogen sulfide, and deuterium oxide (heavy water). Using chemical nomenclature for type I ionic binary compounds, water would take the name "hydrogen monoxide" , but this is not among the names published by the International Union of Pure and Applied Chemistry (IUPAC). Another name is "dihydrogen monoxide", which is a rarely used name of water, and mostly used
Dihydrogen complex separations > 1 Å are better described as dihydride complexes (see figure). The usual method for characterization is H NMR spectroscopy. The magnitude of spin-spin coupling, "J", is a useful indicator of the strength of the bond between the hydrogen and deuterium in HD complexes. For example, "J" is 43.2 Hz in HD but 33.5 Hz in W(HD)(CO)(PPr). Dihydrogen complexes typically have shorter H-spin-lattice relaxation times than the corresponding dihydrides. An ideal if nontrivial method of characterization of dihydrogen complexes is neutron diffraction. Neutrons interact strongly with hydrogen atoms, which allows one to infer their location in a crystal. In