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The question of “Can H2 Make A Hydrogen Bond” might seem straightforward at first glance. After all, hydrogen is in the name! However, the reality is a bit more nuanced and depends on what we consider a “hydrogen bond” to be. Let’s delve into the fascinating details of whether dihydrogen, or H2, can actually participate in this crucial type of intermolecular interaction.
Unpacking Hydrogen Bonding and Dihydrogen’s Role
Hydrogen bonds are a special type of dipole-dipole attraction that occurs between an electronegative atom (such as oxygen, nitrogen, or fluorine) and a hydrogen atom covalently bonded to another electronegative atom. This creates a partial positive charge (δ+) on the hydrogen atom and partial negative charge (δ-) on the electronegative atom. The positively charged hydrogen then interacts with another electronegative atom with a lone pair of electrons. The strength of hydrogen bonds is crucial for many biological and chemical processes, including the structure of DNA and the properties of water.
Now, let’s consider dihydrogen (H2). In an H2 molecule, both atoms are hydrogen, meaning there’s no significant difference in electronegativity. This results in a nonpolar covalent bond. Consequently, neither hydrogen atom carries a significant partial positive charge (δ+). For a molecule to act as a hydrogen bond donor, it *must* have a hydrogen atom that is substantially electron-deficient. Dihydrogen simply does not meet this criterion under normal conditions. To summarize:
- Hydrogen bonds require a significant partial positive charge on the hydrogen atom.
- This partial positive charge arises from the hydrogen being bonded to a highly electronegative atom.
- Dihydrogen (H2) is a nonpolar molecule.
However, recent research indicates that under very specific and extreme conditions, such as high pressure or in the presence of certain metal complexes, dihydrogen can exhibit weak interactions that *resemble* hydrogen bonding. This occurs when the H2 molecule is polarized due to external influences. In these cases, the electron density around one of the hydrogen atoms can be slightly reduced, leading to a very weak δ+ character.
- Under normal circumstances, H2 does not participate in hydrogen bonding.
- Extreme conditions can induce a slight polarization of H2.
- This polarization may lead to weak interactions resembling hydrogen bonds.
Want to learn more about the specifics of these extreme conditions and the research that supports them? Refer to the scientific sources provided in the next section!