H2C
Methylene · Carbene, Methylidene
Methylene is a highly reactive and unstable chemical intermediate consisting of a carbon atom bonded to two hydrogen atoms.
About Methylene
Methylene is a highly reactive, metastable species consisting of a single carbon atom bonded to two hydrogen atoms. Due to its electronic configuration, it acts as a transient intermediate rather than a stable bulk material, making it a subject of intense study in fundamental chemical kinetics and molecular physics. Its insulating electronic character reflects its nature as a discrete molecular entity rather than an extended solid-state lattice. Because it is inherently unstable, it is typically generated in situ during chemical reactions rather than isolated as a traditional crystalline material. Its significance lies in its ability to facilitate complex bond-forming processes, serving as a critical building block in organic synthesis and combustion chemistry.
Key Properties
Cross-validated computational properties for Methylene, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of H2C. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for H2C, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| Pnma (No. 62) | orthorhombic | 6.46 | 0.0347 | -5.797 | 1.04 |
| Pnma (No. 62) | orthorhombic | 6.55 | 0.0358 | -0.141 | — |
| Pnma (No. 62) | orthorhombic | 6.55 | 0.0361 | -0.140 | — |
| P21/c (No. 14) | monoclinic | 6.51 | 0.0403 | -0.136 | — |
| P21/c (No. 14) | monoclinic | 6.72 | 0.0622 | -0.114 | — |
| Amm2 (No. 38) | orthorhombic | 1.85 | 0.8515 | 0.675 | — |
| P1 (No. 1) | triclinic | 1.67 | 0.9642 | 0.788 | — |
| Pmm2 (No. 25) | orthorhombic | 1.34 | 1.0907 | 0.914 | — |
| Pm (No. 6) | monoclinic | 0.00 | 1.1437 | 0.967 | — |
| — | — | 0.00 | 1.3700 | 1.158 | — |
| — | — | 0.00 | 1.6305 | 1.419 | — |
| — | — | 0.00 | 2.4884 | 2.276 | — |
Applications
Where Methylene is used.
Frequently Asked Questions
Common questions about Methylene, answered from cross-validated data.
What is H2C?
Methylene is a highly reactive and unstable chemical intermediate consisting of a carbon atom bonded to two hydrogen atoms.
What is H2C used for?
What is the band gap of H2C?
Is H2C a metal, semiconductor, or insulator?
Is H2C thermodynamically stable?
What is the crystal structure of H2C?
How many polymorphs of H2C are known?
What elements does H2C contain?
Where does the data for H2C come from?
How It Compares
As a fundamental carbene, methylene serves as the prototypical member of its class, defining the reactivity patterns for more complex substituted derivatives. Unlike stable, bulk-phase hydrocarbons, its metastability dictates that it must be handled as a fleeting, high-energy intermediate in specialized laboratory environments.
Data sources & attribution
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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