Syntheses, spectroscopic and structural characterizations of a series of Cu(I)-phenanthroline complexes are reported. A single crystal X-ray structure determination is recorded for CuNO3:dmp:MeCN (1:1:1), ‘dmp’ = 2,9-dimethyl-1,10-phenanthroline, showing it to be isomorphous with its previously studied tetrafluoroborate, perchlorate and hexafluorophosphate, and silver(I) perchlorate counterparts, the metal atom lying in a trigonal planar [(N^N)Cu(NCMe)] coordination environment, the anion not being coordinated. Structure (re-) determinations are also reported for a number of salts of the [Cu(dmp)2]+ cation: the perchlorate, isomorphous with numerous other salts, not only of copper(I), but also lithium(I)), also the unsolvated nitrate, and a solvated form of the chloride.