Crystallization of adducts of simple copper(I) and silver(I) salts (MX) with triphenylphosphine from 'N,N,N′,N'-tetramethylethylenediamine', 'tmeda', has yielded adducts of 1:1:1 MX:PPh3:tmeda stoichiometry, all of which have been characterized by room temperature single crystal X-ray structure determinations. In all adducts, the complex is mononuclear [M(PPh3)(N,N′-tmeda)X] with four-coordinate N2PMX metal atom environments (M = Cu, X = Cl, Br, I; M = Ag, X = Cl or NO3). The tricyclohexylphosphine species [Ag(Pcy3)(N,N′-tmeda)(ONO2)], also in a N2PAgX metal environment, has been defined. A number of similar silver(I) adducts are obtained by using 1,2-diaminopropane, 'pn' as solvent. The chloride, bromide and iodide complexes are isomorphous, the complexes being mononuclear, [Ag(PPh3)(pn)X], with four-coordinate N2PAgX environments, the pn ligand chelating. An isomorphous arsenic analogue of the bromide has also been isolated. All complexes have been characterized by IR and NMR (1H and 31P) spectroscopy.