I think that's not capitalism, that's human nature. On every possible power structure you can think of, there will be people available to compromise on their moral principles if given the right incentives to do so. Under capitalism that's easily money, under other systems it might be something else. You can work to mitigate or detect and deter it (the amount of effort put on that is what makes the difference between limited and widespread corruption). You cannot hope to eliminate it entirely.