Abstract Reliable spectral criteria which allow comparison of the hydrogen and coordination bonds in isostructural systems are suggested. The model systems consist of ArXH and ArXMR n (X= O, S, N; M= Hg, Sn, Pb, Sb; Ar= C 6 H 4 Y where Y= COR, NO 2, C 5 H 4 N, etc.) which interact with various N-, P-and O-bases. The conditions on which the ν XM vibrations are local, have been established. Examination of thiol derivatives reveals the ...