Swiss card- travel to Germany from Switzerland

We plan to fly into Zurich in Sep, purchase Swiss Cards which I understand provide free travel for our inwards leg to Wengen.
We then depart Wengen some 5 days later and travel to Wurzburg in Germany via Frankfurt.
Our exit point from Switzerland is Basel, which I understand is free under the terms of the Card.

Our changeover time in Basel is only seven minutes from IC962 to ICE 74
What are the logistics to purchasing the ongoing point to point Basel Wurzburg?
Can I do that in Switzerland?
Are reservations required?

Your guidance will be appreciated.

Hello Ecca43,

The train from Basel to Germany most probably requires seat reservations. If not, I would recommend it. You can purchase the tickets in Switzerland, but it's better to get such tickets in advance (up to 2-3 months prior to your trip). That increases the chance you'll be able to get them, and get the desired seats if applicable. You can find tickets here. In most cases you can purchase along your Swiss Cards from the same website as well. If you let me know your country of residence I'll point you to the right website.

Australia