The reaction of atomic carbon, C(P-3(j)) with per-deutero benzene, C6D6 is investigated at an average collision energy of 32.1 kJ mol(-1) using the crossed molecular beams technique combined with a universal mass spectrometric detector. Product angular distributions and time-of-flight spectra of C7D5 and C7D6 are recorded. Forward-convolution fitting of our time-of-flight data (TOFs) and laboratory angular distribution (LAB) together with high level electronic structure calculations on the singlet and triplet C7D6 potential energy surfaces are consistent with the formation of the per-deutero-1,2-didehydrocycloheptatrienyl radical, C7D5. No C7D6 adduct is found experimentally. Our investigations indicate that the carbon atom attacks the benzene molecule face without an entrance barrier to form an initial complex. This undergoes a ring opening to give triplet cycloheptatrienylidene as a C7D6 intermediate. The latter fragments without exit barrier via a C-D bond rupture to yield the per-deutero-1,2-didehydrocycloheptatrienyl isomer, C7D5, and a D atom. This barrierless route for the destruction of benzene may be involved in the synthesis of higher cyclic hydrocarbon derivatives in the interstellar medium, in outflows of dying carbon stars, in hydrocarbon-rich planetary atmospheres, as well as in oxygen-poor combustion flames.