Methylene is also a common ligand in coordination compounds, such as copper methylene . Other solvents include nitromethane, dimethyl sulfoxide, and methylene chloride. The fluid is typically dichloromethane, also known as methylene chloride. The phenolic units are mainly linked by methylene and/or ether groups. It can also occur from exposure to methylene chloride. Animal studies indicate that inhalation of methylene chloride affects the liver, kidney, and cardiovascular system. Short-term exposure to high concentrations of methylene chloride also irritates the nose and throat. The International Nonproprietary Name (INN) of methylene blue is methylthioninium chloride. Therapy with ascorbic acid and methylene blue are frequently used in the treatment of methemoglobinemia. It is classically a mixture of eosin (red) and methylene blue dyes. The stereoselectivity of this reaction was further investigated through study of prochiral methylene hydrogen discrimination. Severe methemoglobinemia may be rapidly reversible after treatment with methylene blue. Most are prepared by condensation of the active methylene group with carbonyls. This step is catalyzed by methylene H4MPT dehydrogenase. Unsolvated, excited methylene will form stable ground state oligomers.