Which of the following compound does not contain 3-centred-2-electron bond

• A

  ${\mathrm{B}}_2{\mathrm{H}}_6$

• B

  ${\left[{\mathrm{AlH}}_3\right]}_{\mathrm{n}}$

• C

  ${\left({\mathrm{BeH}}_2\right)}_{\mathrm{n}}$

• D

  ${\mathrm{BCl}}_3$