XPS spectra for cleaned and a 2-aminopyrimidine treated copper plates have been measured from 0.0 to about 1000.0 eV. The spectral features of CU2p3/2 and O-1s peaks indicate Cu2O layer formation on the copper surface. High resolution N-1s XPS spectra recorded for free 2-aminopyrimidine and 2-aminopyrimidine treated copper films indicate that 2-aminopyrimidine reacts with the copper surface forming a [O-Cu(I)-2-AP] complex on an oxidized underlayer. First principles molecular orbital calculations have been performed on an embedded model of 2-aminopyrimidine and on eight assumed surface model cluster complexes. The N 1s level in 2-aminopyrimidine is quantitatively well reproduced. Spectral features within 28 eV of the edge as well as absolute energies are satisfactorily reproduced by the ground state calculation using a minimal basis set. The [O-Cu(I)-2-AP] surface models show theoretical spectra of Cu(I)-pyrimidine ring rr-complexes that agree well with the high resolution N-1s XPS data.