The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Spectra and structure of pyridine coordination compounds》. Authors are Herbelin, F.; Herbelin, J. D.; Mathieu, J. P.; Poulet, H..The article about the compound:cis-Dichlorobis(pyridine)platinum(II)cas:15227-42-6,SMILESS:[Cl-][Pt+2]([N]1=CC=CC=C1)([Cl-])[N]2=CC=CC=C2).Recommanded Product: cis-Dichlorobis(pyridine)platinum(II). Through the article, more information about this compound (cas:15227-42-6) is conveyed.
Ir absorption spectra of 15 coordination compounds of pyridine with Pt, Rh, and Ir have been observed, 100-3200 cm.-1; in some cases uv and Raman spectra have also been observed. The effect of coordination on the vibration spectrum of pyridine, the structure of the coordinated units, and the differences in the spectra of cis-trans isomers are discussed.
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Reference:
Tetrahydroisoquinoline – Wikipedia,
1,2,3,4-Tetrahydroisoquinoline | C9H11N – PubChem