Officers in the war

During the Civil War were there ever times where the Union army or Confederate army tried or thought about buying or persuading an officer from the other side to join the opposition? Seeing how Robert E. Lee was so dominate for the Confederates in the east, I would think that the Union army could have used him or wanted him because of his great leadership. Seeing how the Union was psychologically weak in the beginning of the war. Buying an officer such as Lee could have been a great strategy to lift the spirits of the soldiers.