Methylcyclopentadienylmanganese tricarbonyl
[CAS# 12108-13-3]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic manganese
• Name: Methylcyclopentadienylmanganese tricarbonyl
• Synonyms: Tricarbonyl(2-methylcyclopentadienyl)manganese; Tricarbonyl(methylcyclopentadienyl)manganese
• Molecular Formula: C₉H₇MnO₃
• Molecular Weight: 218.09
• CAS Registry Number: 12108-13-3
• EC Number: 235-166-5
• SMILES: CC1C=C[C-]=C1.[C-]#[O+].[C-]#[O+].[C-]#[O+].[Mn]

Properties

• Density: 1.39
• Melting point: 2.2 °C
• Boiling point: 233 °C

Safety Data

• Hazard Symbols: GHS06;GHS08;GHS09 Danger
• Risk Statements: H301-H310+H330-H315-H372-H410
• Safety Statements: P262-P273-P280-P302+P352+P310-P304+P340+P310-P314

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	2	H310
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Acute toxicity	Acute Tox.	2	H300
Acute toxicity	Acute Tox.	1	H330
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute toxicity	Acute Tox.	3	H301
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Skin irritation	Skin Irrit.	2	H315
Carcinogenicity	Carc.	2	H351
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	2	H311
Acute toxicity	Acute Tox.	1	H300
Acute toxicity	Acute Tox.	2	H330

Discovery and Applications

Methylcyclopentadienylmanganese tricarbonyl (MMT) is a chemical compound that has garnered attention for its applications in the field of catalysis and as an additive in gasoline formulations. Discovered in the mid-20th century, MMT is characterized by its unique structure, which consists of a methylcyclopentadienyl ligand coordinated to a manganese atom, along with three carbonyl groups. This coordination complex is notable for its role in enhancing combustion efficiency and reducing emissions in internal combustion engines.

The synthesis of methylcyclopentadienylmanganese tricarbonyl involves the reaction of manganese carbonyl compounds with methylcyclopentadiene. The resulting complex is a liquid at room temperature and exhibits significant volatility, making it suitable for use as an additive in fuels. MMT functions primarily as a fuel additive to improve the octane rating of gasoline, which is a critical property affecting engine performance. By increasing the octane number, MMT allows for more efficient combustion, leading to improved power output and fuel economy.

One of the primary advantages of using MMT as an octane booster is its ability to reduce engine knock, which is a phenomenon that occurs when fuel combusts prematurely in the engine cylinder. By enhancing the fuel's octane rating, MMT enables engines to operate more smoothly and efficiently, reducing the likelihood of knocking and extending engine life. The use of MMT in gasoline has been particularly beneficial in high-performance vehicles, where the demand for higher octane fuels is critical for optimal engine operation.

In addition to its role as an octane enhancer, methylcyclopentadienylmanganese tricarbonyl has been studied for its potential as a catalyst in various chemical reactions. The presence of the manganese center in MMT allows it to participate in catalytic processes, including carbonylation and oxidation reactions. MMT has been investigated as a catalyst in the synthesis of fine chemicals and pharmaceuticals, where its unique coordination environment can facilitate the activation of substrates and improve reaction selectivity.

The discovery of MMT and its applications in both fuel formulations and catalysis have made it a subject of interest in environmental studies. While MMT was initially embraced for its benefits in enhancing fuel performance, concerns have been raised regarding its environmental impact. The combustion of MMT can lead to the formation of manganese emissions, which have been associated with potential health risks and environmental contamination. Consequently, regulatory agencies have imposed restrictions on the use of MMT in fuel formulations in some regions.

Despite these concerns, research into safer alternatives to MMT has spurred the development of novel manganese-based compounds that aim to achieve similar benefits without the associated risks. The study of MMT continues to inform the development of new catalytic systems and fuel additives that balance performance with environmental considerations.

Methylcyclopentadienylmanganese tricarbonyl exemplifies the dual role of a chemical compound in enhancing performance while also raising awareness of its environmental implications. As industries continue to seek solutions for improving fuel efficiency and reducing emissions, the legacy of MMT as a pioneering fuel additive and catalyst will influence future developments in the field.

References

1974. Metabolic aspects of methylcyclopentadienyl manganese tricarbonyl in rats. Environmental Research.
DOI: 10.1016/0013-9351(74)90049-8

2003. Effect on exhaust emissions by the use of methylcyclopentadienyl manganese tricarbonyl (MMT) fuel additive and other lead replacement gasolines. The Science of The Total Environment.
DOI: 10.1016/s0048-9697(02)00476-x

2004. Health and environmental testing of manganese exhaust products from use of methylcyclopentadienyl manganese tricarbonyl in gasoline. The Science of the total environment.
DOI: 10.1016/j.scitotenv.2004.04.043