1142 Methylcyclopentadienyl manganese tricarbonyl Methylcyclopentadienyl manganese tricarbonyl (MMT) is a chemical compound of manganese. It was initially used as a supplement to the gasoline additive tetraethyl lead to increase a fuel's octane rating, then later also used in unleaded gasoline. It has been banned in various countries in the past due to its toxicity, but is available in most places today, despite controvery over its safety. Manganese is a naturally occurring metal with the symbol Mn and the atomic number 25. It does not occur naturally in its pure form, but is found in many types of rocks in combination with other substances such as oxygen, sulfur, or chlorine. Manganese occurs naturally in most foods and small amounts are needed to stay healthy, as manganese ions act as cofactors for a number of enzymes. (L228, L229, L239) 12108-13-3 25511 C9H7MnO3 Yellow to dark orange liquid. 1.5°C 0.029 mg/mL at 25°C [GARRISON,AW et al. (1995)] Oral (L228) ; inhalation (L228) Manganese is a cellular toxicant that can impair transport systems, enzyme activities, and receptor functions. It primarily targets the central nervous system, particularily the globus pallidus of the basal ganglia. It is believed that the manganese ion, Mn(II), enhances the autoxidation or turnover of various intracellular catecholamines, leading to increased production of free radicals, reactive oxygen species, and other cytotoxic metabolites, along with a depletion of cellular antioxidant defense mechanisms, leading to oxidative damage and selective destruction of dopaminergic neurons. In addition to dopamine, manganese is thought to perturbations other neurotransmitters, such as GABA and glutamate. In order to produce oxidative damage, manganese must first overwhelm the antioxidant enzyme manganese superoxide dismutase. The neurotoxicity of Mn(II) has also been linked to its ability to substitute for Ca(II) under physiological conditions. It can enter mitochondria via the calcium uniporter and inhibit mitochondrial oxidative phosphorylation. It may also inhibit the efflux of Ca(II), which can result in a loss of mitochondrial membrane integrity. Mn(II) has been shown to inhibit mitochondrial aconitase activity to a significant level, altering amino acid metabolism and cellular iron homeostasis. (L228) Manganese is absorbed mainly via ingestion, but can also be inhaled. It binds to alpha-2-macroglobulin, albumin, or transferrin in the plasma and is distributed to the brain and all other mammalian tissues, though it tends to accumulate more in the liver, pancreas, and kidney. MMT is metabolized by cytochrome P-450 enzymes into hydroxylmethylcyclopentadienyl manganese tricarbonyl and carboxycyclopentadienyl manganese tricarbonyl. These metabolites are excreted in the urine and faeces. (L228) LD50: 140-795 mg/kg (Dermal, Rabbit) (T32) LD50: 58 mg/kg (Oral, Rat) (A178) LC50: 247 mg/m3 over 1 hour (Inhalation, Rat) (T32) No indication of carcinogenicity to humans (not listed by IARC). Methylcyclopentadienyl manganese tricarbonyl (MMT) is a chemical compound of manganese. It was initially used as a supplement to the gasoline additive tetraethyl lead to increase a fuel's octane rating, then later also used in unleaded gasoline. It has been banned in various countries in the past due to its toxicity, but is available in most places today, despite controvery over its safety. (L239) Chronic Inhalation: 0.0003 mg/m3 (L134) Manganese mainly affects the nervous system and may cause behavioral changes and other nervous system effects, which include movements that may become slow and clumsy. This combination of symptoms when sufficiently severe is referred to as “manganism”. (L228) Manganese mainly affects the nervous system and may cause behavioral changes and other nervous system effects, which include movements that may become slow and clumsy. This combination of symptoms when sufficiently severe is referred to as “manganism”. (L228) 2009-06-19T21:58:21Z 2026-04-03T06:50:28Z Alpha-2-macroglobulin (P01023) Serum albumin (P02768) Serotransferrin (P02787) Superoxide dismutase [Mn], mitochondrial (P04179) (L228) MN%2b3 C009907 Methylcyclopentadienyl manganese tricarbonyl 4267 true Alpha-2-macroglobulin (P01023) Serum albumin (P02768) Serotransferrin (P02787) (L228) [Mn].[C-]#[O+].[C-]#[O+].[C-]#[O+].CC1=CC=C[CH]1 C9H7MnO3 InChI=1S/C6H7.3CO.Mn/c1-6-4-2-3-5-6;3*1-2;/h2-5H,1H3;;;; LYHJNAIHGFWRKM-UHFFFAOYSA-N 218.0881 217.977568726 Exogenous Liquid 17215408 CHEM000970 DTXSID9027738 NS00019422 2-methylcyclopenta-2,4-dien-1-yl tris(methanidylidyneoxidanium) manganese