Answer:
See explanation
Explanation:
Both BCl3 and BH3 are electron deficient compounds. In these compounds, boron has six instead of eight electrons surrounding it's outermost shell.
BH3 is able to form a dimmer because of the small size of hydrogen atoms which enable them to be fitted between boron atoms. Large size chlorine atoms can not be fitted between boron atoms hence B2Cl6 does not exist.
