Chiral [Formula Presented]-exchange [Formula Presented] potentials: Relativistic [Formula Presented] corrections

We calculate in baryon chiral perturbation theory the relativistic [Formula Presented] corrections to the leading order two-pion exchange diagrams. We give explicit expressions for the corresponding one-loop [Formula Presented] amplitudes in momentum space. The resulting isovector central and isoscalar spin-spin and tensor [Formula Presented] amplitudes involve nonstatic terms proportional to the squared nucleon center-of-mass momentum [Formula Presented] From the two-pion exchange box diagrams we obtain an isoscalar quadratic spin-orbit [Formula Presented] amplitude. We give also analytical expressions for the corresponding [Formula Presented] potentials in coordinate space. The diagrammatic results presented here make the chiral [Formula Presented] potential complete at next-to-next-to-next-to-leading order.