Which compound contains diborane?

Diborane is a chemical compound represented by the formula B₂H₆. It consists of two boron atoms and six hydrogen atoms, making it a unique hydride of boron. Diborane has distinctive properties and is often used in various chemical applications, particularly as a reducing agent and in organic synthesis.

The other compounds listed do not represent diborane. For example, B₃H₆ refers to triborane, which has a different structure and composition. B₂O₃ is boron trioxide, a compound containing oxygen and not hydrogen, whereas B₃N₃H₆ is a boron-nitrogen-hydrogen compound that includes nitrogen alongside boron and hydrogen, further distinguishing it from diborane. Thus, the formula B₂H₆ is specifically characteristic of diborane, confirming it is the correct choice.