I would be surprised if Russian oil and military industries were dependent on European capital markets in a meaningful way. Such a dependence would indicate a failure in Russian strategic thinking. The Russian companies should be able to secure adequate financing from Russian Banks or from the Russian government. If foreign loans are needed, Russia can borrow from China.
If critical Russian industries are dependent on European capital markets, the sanctions will help Russia by forcing an end to this debilitating dependence. Russia should not be dependent on the West in any way.
The real question is the purpose of the sanctions. My conclusion is that the purpose of the sanctions is to break up and undermine Europe's economic and political relations with Russia.