Microwave discharge through CS2 vapor yielded CS which was cocondensed with laser-ablated copper atoms at 12 K in an argon matrix. Binary copper thiocarbonyl complexes: CuCS, Cu(CS)(2), and Cu2CS were formed via the reactions of ground state copper atoms or dimers with CS in solid argon. On the basis of isotopic shifts and splittings as well as density functional calculations, absorptions at 1187.2, 1291.3, and 1353.9 cm(-1) are assigned to the C-S stretching vibrations of the bent CuCS, linear Cu(CS)(2), and end-on bonded Cu2CS molecules, respectively. The calculation results show that these copper thiocarbonyl complexes are more strongly bonded than the corresponding copper carbonyl complexes. (C) 2003 American Institute of Physics.