At room temperature, the reaction of metallic copper powder with 2-thenoyltrifluoroacetone (tfac) and selected phosphine ligands gives the new copper(I) complexes [Cu(PPh3)(2)(tfac)] (1), [Cu(dppm)-(tfac)](2) (2), [Cu(dppe)(tfac)](2) (3), [Cu(dppp)(tfac)] (4), [Cu(dppb)-(tfac)](2) (5), Ph2P(CH2)(n)PPh2 [n = 1 (dppm), 2 (dppe), 3 (dppp), 4 (dppb)]. These complexes have been characterized by physicochemical and spectroscopic methods. X-ray structure analysis of 1 and 3 shows that tfac behaves as a chelating ligand and dppe coordinates as a bridging bidentate ligand to Cu(I) atoms in the Cu(I) complexes. (C) 2001 Elsevier Science B.V. All rights reserved.