  We report neutron diffraction and transport results on the newly discovered
superconducting nitride ThFeAsN with $T_c=$ 30 K. No magnetic transition, but a
weak structural distortion around 160 K, is observed cooling from 300 K to 6 K.
Analysis on the resistivity, Hall transport and crystal structure suggests this
material behaves as an electron optimally doped pnictide superconductors due to
extra electrons from nitrogen deficiency or oxygen occupancy at the nitrogen
site, which together with the low arsenic height may enhance the electron
itinerancy and reduce the electron correlations, thus suppress the static
magnetic order.
