What are the uses and toxicity of Methylcyclopentadienyl manganese tricarbonyl

Description

Methylcyclopentadienyl manganese tricarbonyl (MMT) is a pleasant-smelling orange liquid with a faint vanilla flavor. It has the formula C9H7MnO35* and is slightly soluble in water and denser than water. Because it is highly toxic, inhalation, ingestion, or skin absorption can cause poisoning. Therefore, it needs to be stored separately from food raw materials. It is combustible and breaks down toxic manganese oxide fumes in the field. At present, a large number of studies on its toxicity have been published.

Uses

Methylcyclopentadienyl manganese tricarbonyl is an organomanganese compound that is used as an octane enhancer for gasoline and other fuels. It was originally used as a supplement to leaded gasoline and later for unleaded gasoline with an increased octane rating[1]. Methylcyclopentadienyltricarbonylmanganese can be used to dope ZnSe nanocrystals or as a raw material to participate in a variety of chemical reactions.

Toxicity and hazard

Since the combustion of MMT in gasoline produces MnPO₄ and the formation of MnSO₄, MMT is considered the latest source of inorganic manganese in high-traffic areas of cities[2]. Manganese can be a nerve poison at sufficiently high exposure levels that may cause irreversible neurotoxicity or other adverse health effects. MMT may produce alveolar inflammation and bronchiolar cell injury. Komura et al. found that norepinephrine levels in the cerebellum-fed MMT-containing feed were significantly increased and correlated with manganese concentrations. Manganese concentration in the cerebellum in the MMT-exposed group increased significantly compared to the control group and the MnCl₂ exposure group[3]. Zhu et al. found that exposure to a certain dose of MMT and MnCl2 led to slower weight gain in female rats and structural changes in the substantia nigra dense region (SNpc), so exposure to MMT led to ultrastructural changes in SNpc neurons, ultimately leading to changes in motor behavior and cognition. Studies have found that the toxic effect of MMT was inhibited by quercetin, an antioxidant flavonoid[4].

References

[1] Halatek T, et al. Pulmonary response to methylcyclopentadienyl manganese tricarbonyl treatment in rats: injury and repair evaluation.Histology and Histopathology, 2006; 21: 1181-1192.

[2] Pfeifer G, et al.Health and environmental testing of manganese exhaust products from use of methylcyclopentadienyl manganese tricarbonyl in gasoline. Science of the Total Environment, 2004; 334-335: ;397-408.

[3] Zhu Q, et al. Methylcyclopentadienyl Manganese Tricarbonyl Alter Behavior and Cause Ultrastructural Changes in the Substantia Nigra of Rats: Comparison with Inorganic Manganese Chloride. Neurochemical Research, 2022; 47: 2198–2210.

[4] Komura J, et al. Chronic oral administration of methylcyclopentadienyl manganese tricarbonyl altered brain biogenic amines in the mouse: comparison with inorganic manganese. Toxicology Letters, 1994; 73: 65-73.