Answer Happy

2. Pentaborane, B5H9, is an important precursor for higher
boranes. It is prepared by the thermal degradation of even lower
boranes, as shown below: a. Provide a balanced equation for step 2.
[1 mark] b. Using Wade’s Rules, predict the structure of B5H9. [2
marks] c. B5H9 can be reduced by elemental sodium to give the salt
Na2B5H9 – what happens to the cage in this process and why? [3
marks] d. Reaction of Na2B5H9 with silicochloroform (HSiCl3) at
high temperature results in the formation of a new cluster,
NaSiB5H6. Using Wade’s rules, predict the structure of the cluster.
How many environments will it possess in the 1H and 11B{1H} NMR
spectra? [4 marks]
2. Pentaborane, B;Hg, is an important precursor for higher boranes. It is prepared by the thermal degradation of even lower boranes, as shown below: Na[B3Hg] + HCI Na[B3H7CI] + H2 Step 1 Na[B3H7CI] B5Hg + NaCl + H2 Step 2 a. Provide a balanced equation for step 2. [1 mark] b. Using Wade's Rules, predict the structure of B3H9. [2 marks] C. BšH, can be reduced by elemental sodium to give the salt Na2B$H– what happens to the cage in this process and why? [3 marks] d. Reaction of Na2BsH, with silicochloroform (HSiC13) at high temperature results in the formation of a new cluster, NaSiBsH6. Using Wade's rules, predict the structure of the cluster. How many environments will it possess in the 'H and 11B{"H} NMR spectra? [4 marks)