The key difference between borazine and diborane is that borazine contains three boron atoms per molecule, whereas diborane contains two boron atoms per molecule.
Borazine and diborane are boron-containing chemical compounds. Both these are cyclic compounds with different numbers of ring-members.
CONTENTS
1. Overview and Key Difference
2. What is Borazine
3. What is Diborane
4. Side by Side Comparison – Borazine vs Diborane in Tabular Form
5. Summary
What is Borazine?
Borazine is a cyclic, inorganic compound having the chemical formula B3H6N3. It is a cyclic compound with a six-membered ring structure. That is, it has three B-H units and three N-H units in an alternating pattern. Therefore, we can write its chemical formula as (BH3)(NH3). Also, this structure is isoelectronic with the benzene ring. Like benzene, this too is a colourless liquid at room temperature. Therefore, we sometimes call it “inorganic benzene”.
Figure 01: Structure of Borazine
Furthermore, the molar mass of borazine is 80.50 g/mol. The melting point and boiling points are −58 °C and 53 °C, respectively. It also has an aromatic smell. Moreover, this is a synthetic compound we can produce from diborane and ammonia at 1:2 ratio.
The chemical reaction involved in this process is as follows:
3 B2H6 + 6 NH3 → 2 B3H6N3 + 12 H2
Above all, if we add borazine to water, it will hydrolyze to give boric acid, ammonia and hydrogen gas. In addition, this compound is thermally very stable due to its low standard enthalpy change of formation; −531 kJ/mol. Compared to benzene, borazine is far more reactive. For example, it can react with hydrogen chloride while benzene cannot.
According to X-ray crystallographic determinations, the bond lengths in the ring structure of borazine are equal. However, it cannot form a perfect hexagon because the alternating pattern of nitrogen and boron gives different bond angles and thus, a distinct molecular symmetry.
What is Diborane?
Diborane is an inorganic compound having the chemical formula B2H6. This compound contains boron and hydrogen atoms in a cyclic structure. It occurs as a colourless and pyrophoric gas. It has a repulsive sweet odour as well. The molar mass of diborane is 27.67 g/mol.
Figure 02: Structure of Diborane
Diborane is considered as an electron-deficient molecule. This is because it does not have enough valence electrons to form a separate two-electron bond between each pair of bonded atoms. Moreover, it is the reason for the cyclic or bridged structure of diborane molecule.
When considering the properties of diborane, it is a colourless and flammable gas at room temperature. It is also a toxic gas. When burnt in the presence of oxygen in the air, diborane can release a high amount of energy. When this gas is mixed with water, it rapidly hydrolyzes, giving boric acid and hydrogen gas.
What is the Difference Between Borazine and Diborane?
The key difference between borazine and diborane is that borazine contains three boron atoms per molecule, whereas diborane contains two boron atoms per molecule. Moreover, another difference between borazine and diborane is that borazine is a colourless liquid, while diborane is a colourless and flammable gas. Besides, borazine is formed from the reaction between diborane and ammonia while diborane is formed from the reaction between metal hydrides and boron.
Below is a tabulation of the difference between borazine and diborane.
Summary – Borazine vs Diborane
Borazine and diborane are cyclic structures. The key difference between borazine and diborane is that borazine contains three boron atoms per molecule, whereas diborane contains two boron atoms per molecule.
Reference:
“Diborane – Structure of Diborane, Preparation, Properties, Uses.” BYJUS, BYJU’S, 16 Dec. 2019, Available here.
“Diborane.” Wikipedia, Wikimedia Foundation, 6 Feb. 2020, Available here.
Image Courtesy:
1. “Borazine-dimensions-2D” By Hbf878 – Own work (CC0) via Commons Wikimedia
2. “Diborane-2D” (Public Domain) via Commons Wikimedia