We report a critical re-evaluation of the synthesis and characterization of Cu-8(MPP)(4). This product was reportedly formed by the reaction of Cu(NO3)(2) with 2-mercapto-5-n-propylpyrimidine (HMPP) and NaBH4, in ethanol, in the presence of [N(C8H17)(4)][Br]. In our hands, we found no experimental evidence to support the existence of Cu-8(MPP)(4) in the reaction mixture. Instead, we demonstrate that the material isolated from this reaction is a complex mixture containing [N(C8H17)(4)](+), Br-, NO3-, and 2-mercapto-5-n-propyl-1,6-dihydropyrimidine (H2MPP*), along with the Cu(I) coordination polymer, [Cu(MPP)](n). To support our conclusions, we have independently synthesized H2MPP* and [Cu(MPP)](n), as well as the related Cu(I) coordination complexes, [Cu(HMPP*)]n and [Cu-2(MPP*)](n). All new materials were characterized by NMR spectroscopy and mass spectrometry, while H2MPP*, [Cu(HMPP*)](n) (n = 4), and [Cu(MPP)](n) (n = 6) were also characterized by X-ray crystallography.