© 2017 American Physical Society. Fragmentation of molecular nitrogen dimers (N2)2 induced by collision with low energy 90 keV Ar9+ ions is studied to evidence the influence of a molecular environment on the fragmentation dynamics of N2 cations. Following the capture of three or four electrons from the dimer, the three-body N2++Nm++Nn+ [with (m,n)=(1,1) or (1, 2)] fragmentation channels provide clean experimental cases where molecular fragmentation may occur in the presence of a neighbor molecular cation. The effect of the environment on the fragmentation dynamics within the dimer is investigated through the comparison of the kinetic energy release (KER) spectra for these three-body channels and for isolated N2(m+n)+ monomer cations. The corresponding KER spectra exhibit energy shifts of the order of 10 eV, attributed to the deformation of the Nm++Nn+ potential energy curves in the presence of the neighboring N2+ cation. The KER structures remain unchanged, indicating that the primary collision process is not significantly affected by the presence of a neighbor molecule.