Laser ablated niobium and tantalum atoms have been reacted with CO molecules during condensation in excess neon. The Nb(CO)(x) and Ta(CO)(x) (x = 1-6) carbonyls formed during sample deposition or on annealing are the major products. The novel CNbO carbide-oxide molecule was produced on visible photolysis via isomerization of the NbCO carbonyl. The ONbCCO and OTaCCO molecules were formed by near-UV-vis photon-induced rearrangement of the Nb(CO)(2) and Ta(CO)(2) dicarbonyls and further rearrange to the (C-2)NbO2 and (C-2)TaO2 molecules on UV photolysis. Evidence is also presented for the CNbO-, CTaO-, Nb(CO)(x)(-), and Ta(CO)(x)(-) anions. The product absorptions were identified by isotopic substitution ((CO)-C-13-O-16, (CO)-C-12-O-18, and mixtures), electron trapping with added CCl4 and density functional calculations of isotopic frequencies.