Diazomethane (CH2N2) is an explosive yellow gas. It is transported in the liquid phase and has a musty odor. If inhaled, it is highly toxic. In this diazomethane molecule, the methylene is attached to the diazo group, thus forming this simple diazo compound.
This is one of the dangerous chemicals as it has application as poison and a potential carcinogenic agent. It can also be used as an alkylating agent. If inhaled, it could lead to many health issues such as eye irritation, throat irritation, cough, breathing troubles, asthma, pneumonia, weakness, dizziness, and chest pains. Due to its highly hazardous nature, diazomethane is preferred to use on a smaller scale compared to an industrial scale.
For example, even when being used in the laboratory scale, there should be utmost care taken while using the diazomethane. In case there is any sharp edge or even small scratches, then the diazomethane would explode. Hence, it is always used under the heavy supervision of cleaned glassware. It is also highly recommended to use the blast shield while using these compounds in the laboratory.
Diazomethane does not tolerate a high temperature of about a hundred degrees Celsius. It will explode at such a higher temperature. It also results in an explosion when there is a high-intensity light exposure to this substance. Due to this, this compound is mostly used only in laboratories and not on large scale.
CH2N2 Lewis Structure
In order to understand the arrangement of atoms or electrons in the molecules, the electron dot structure or Lewis structure is studied. The interaction among various molecules is analyzed with the help of Lewis structures of molecules. This interaction among the atoms or electrons defines the physics properties of the molecules.
In general, the lewis structure describes the arrangement of electrons in the valence shell of a molecule. In such structures, the electrons are represented as the dots and hence also known as the electron dot structure.
Before analyzing the Lewis structure of a molecule, it is necessary to study the octet rule. According to the octet rule, there can be a maximum of eight electrons around an atom in a molecule. It satisfies the valency of most of the atoms, except, hydrogen. For hydrogen, it follows the duplet rule, where the maximum number of valence electrons can be only two.
In the perfect Lewis structure, all the atoms in a molecule will be satisfied with their valence electrons. There are four basic steps in the creation of the lewis structure of any molecule.
Step 1: Determine the valence electrons in the molecule:
The diazomethane or CH2N2 has the carbon atom with four valence electrons, has two hydrogen atoms with one valence electron each, and two nitrogen atoms with five valence electrons in each of them.
Therefore, the total number of valence electrons in diazomethane molecule is calculated as follows:
CH2N2= 4+ 1(2) + 5(2) = 16
Step 2: Determine and place the atoms:
In this step, the most suitable atom to be placed in the center of the electron dot structure is determined. With the greater number of valence electrons among the other atoms, carbon and nitrogen will be placed in the center.
Around the carbon atom, the hydrogen atoms are placed and then the nitrogen atoms are placed linearly. Let us consider that the valence electrons are placed as follows:
Below is the lewis structure of Diazomethane with an incomplete octet.
In the above case, the total number of valence electrons is 16 as mentioned in the earlier step. But the octet is not complete for carbon and nitrogen atoms in the center.
There are only six electrons around in the valence of carbon and in the nitrogen atom. To achieve a complete octet in these two atoms, the bond formed needs to be changed.
Step 3: Formation of chemical bonds.
In the process of bond formation, a single bond is formed by sharing two electrons whereas a double bond is formed by sharing four electrons. Instead of a single bond in between the carbon and nitrogen atom, if the double bond is used, then all the nitrogen, hydrogen, and carbon atoms achieve their octets.
Step 4: Octet completion on the atoms.
Consider this structure given below.
In the above structure, the octet is completed in a carbon atom. Simultaneously octet is achieved in nitrogen atoms and duplet is achieved in the hydrogen atoms.
CH2N2 Molecular Geometry
Diazomethane or CH2N2 is a linear molecule. The molecule has two double bonds and two single bonds shared among the carbon and nitrogen atoms. The molecular structure of the compound is studied with the help of the Valence Shell Electron Pair Repulsion (VSEPR) theory.
This theory dictates the shape of the chemical compound. According to this theory, diazomethane is a linear molecule. The following are the resonance structures of the molecules, diazomethane.
When the negative charge on the molecule is stabilized on different atoms in the molecule, it results in the resonating structures of the molecule. In this case, they are formed due to the stabilization of the negative charges on carbon and nitrogen atoms.
Below is the attached VSEPR chart that gives out the shape based on the annotation of the molecule.
Hybridization is the fusing of atomic orbitals to form the new hybridized orbitals where the electrons are paired to form the chemical bonds.
That is, two atomic orbitals with the same energy levels are mixed to form a degenerated new orbital. The orbitals that are mixed can be either fully filled or partially filled but must have the same energy. There are different types of hybridization formed depending on the orbitals mixed. They are sp, sp2, sp3, sp3d, sp3d2, sp3d3.
To illustrate, in a carbon atom, there are four valence shells. Among these, s orbital combines with the three p orbitals to form the four sp3 hybridized orbitals. This results in the carbon atom forming four bonds with four atoms.
Diazomethane has a carbon atom with three sigma bonds and one pi bond. Hence, the carbon is sp2 hybridized in CH2N2 molecule.
The polarity of the compound is defined by the presence of the atoms having different electronegativities. That is, there occurs a charge separation. The difference in electronegativity leads to the polarity between two ions or between two atoms in an ionic or covalent bond, respectively.
With the increase in the difference between electronegativities, the polarity increases. The polarity of the molecules is measured using the dipole moment.
To determine whether a molecule is a polar or a nonpolar molecule, the overlap of the charges is studied. The dipole moments in the molecules with symmetry will cancel each other resulting in the nonpolar molecule. Whereas the molecule without symmetry is a polar molecule due to the presence of dipole moments.
In this case, diazomethane is a polar compound. Due to the difference in the electronegativity between the bonded carbon and nitrogen atoms present in the compound, the diazomethane becomes a polar compound.
Nitrogen being the more electronegative atom than the carbon atom tries to pull the negative charge towards itself. This creates a negative charge in the molecule. This also results in different resonating structures as seen above.
Diazomethane can react with various compounds. For example, it reacts with deuterium in the basic solutions to form the derivative compound of deuterium. Diazomethane can also react with alcohols to give methyl ethers in the presence of boron trifluoride. It is also used to convert the acids to methyl esters.
Diazomethane majorly used as a methylating agent. Though, it is used only in laboratories since it is dangerous to use in industrial processes.
A few of the other names for diazomethane are as follows: Azimethylene Methane, diazo-Acomethylene, Diazonium methylide.
Diazomethane has an sp2 hybridized carbon atom. It is a polar molecule with resonating structures. The resonance structures have the negative charges stabilized over the carbon and nitrogen atoms.