  Transport through molecular contacts with a sluggish intramolecular
vibrational mode strongly coupled to excess charges is studied far from
equilibrium. A Born-Oppenheimer approximation in steady state reveals voltage
dependent energy surfaces which cause abrupt conformational changes of the
molecular backbone. These are directly related to transitions between current
plateaus which are relatively robust against thermal fluctuations and appear in
patterns reminiscent of Coulomb diamonds. In a regime accessible in experiments
bias and gate voltages allow for an efficient control of charge transfer or may
trigger a molecular rotor.
