Laser-ablated Cr atoms react with CO ((CO)-C-12-O-16, (CO)-C-13-O-16, (CO)-C-12-O-18) in excess argon to give the same Cr(CO)(3.4,5) species observed from the photodissociation of Cr(CO)(6). Similar reactions in excess neon give neon matrix fundamentals between argon matrix and gas-phase values. The dicarbonyl Cr(CO)(2) is bent with 1970.8, 1821.5 cm(-1) and 1982.1, 1832.9 cm(-1) C-O stretching fundamentals in solid argon and neon, respectively. The high-spin CrCO molecule appears at 1975.6 and 2018.4 cm(-1) in solid argon and neon, respectively, and exhibits a strong matrix interaction. The CrCO+ cation and Cr(CO)(2)(-) anion are observed in laser-ablation experiments in solid neon at 2200.7 and 1705.0 cm(-1), respectively. The Cr-2(CO)(2) complex absorbs strongly at 1735.4 cm(-1) and gives several combination bands in neon. Density functional theory calculations support the vibrational assignments.