Paramagnetic compounds can't damage a NMR. I run NMRs on Gd, Eu, Tb, and Dy complexes all of the time. Gd is also your main contrast agent for MRI which is just an NMR. Now you maybe messing up your tune by placing them in the magnet but you just need to retune it is all. And I have done this on both very old Varian INOVA 400 MHz 23 years old to a new bruker 600 MHz AvanceIII.
Dan