A first -ray study of spectroscopy was performed at the Radioactive Isotope Beam Factory with projectiles at 217 MeV/nucleon, impinging on the liquid hydrogen target of the MINOS device. Prompt deexcitation rays were measured with the NaI(Tl) array DALI2. Through the one-proton knockout reaction , a spin assignment could be determined for the low-lying states of from the momentum distribution obtained with the SAMURAI spectrometer. A spin-parity is deduced for the ground state of , similar to the recently studied isotope . The evolution of the energy difference is compared to state-of-the-art theoretical predictions.