Tetradentate phosphinoamines N,N'-bis[2-(diphenylphosphino)phenyl]ethane-1,2-diamine (H-2dpen) and N,N'-bis[2-(diphenylphosphino)phenyl]propane-1,3-diamine stabilize copper(I) complexes either by ligand-exchange reactions from labile [Cu(I)(MeCN)4]+ or ligand-promoted reduction of a Cu(III)Cl2.2H2O precursor; the structure of one of the products, [Cu(H-2dpen)]BF4, has been determined.