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 some cases, hydrogen ligands are usefully characterized by X-ray crystallography, but often the presence of metals, which strongly scatter X-rays, complicates the analysis. The triangular MH subunit has six normal modes of vibration, one of which is mainly of ν character. In free H, this very strong bond absorbs at 4300 cm, whereas in dihydrogen complexes the frequency drops to around 2800 cm. Two preparation methods involve the direct reactions with H gas. The first entails the addition of H to an unsaturated metal center, as originally reported for W(CO)(P-i-Pr)(H). In such cases, the unsaturated complex in fact features an