Metal compound clusters containing niobium and carbon are produced in a laser vaporization pulsed-nozzle cluster source. The mass distributions of cations produced from this source are measured under different conditions. These cations are mass-selected in a specially designed reflectron time-of-flight mass spectrometer and photodissociated at various laser wavelengths. Mass distributions provide evidence for the preferential formation of the M(g)C(12) stoichiometry observed previously and associated with the "met-cars" cage structure. Additional abundant masses indicate the formation of face-centered-cubic crystallite stoichiometries. Photodissociation in both the met-cars and crystallite systems results in the formation of a broad distribution of fragment ions, with some enhancement in abundance for the smaller symmetric crystallites. This photochemistry is markedly different from that observed previously for metal-carbon clusters containing titanium, vanadium, molybdenum, or zirconium.