In general, if the atoms that make up the ring contain heteroatoms, such rings become heterocycles, and organic compounds containing heterocycles are called heterocyclic compounds. An article called Unusual chemical behavior and molecular structure of a platinum(II) complex with N,N-diethylhydroxylamine, published in 1992-09-30, which mentions a compound: 15227-42-6, Name is cis-Dichlorobis(pyridine)platinum(II), Molecular C10H10Cl2N2Pt, Category: tetrahydroisoquinoline.
cis-[PtL2Cl2] (L = Et2NOH) was prepared by the reaction of K2PtCl4 with L. cis-[PtL2Cl2] does not react with amines (NH3, pyridine, Et2NOH) and L does not react with cis-[PtA2Cl2] (A = NH3, py). cis-[PtL2Cl2] is monoclinic, space group C2, a 7.569(2), b 12.384(7), c 15.428(2) Å, β 100.00(2)°, Z = 4, R = 0.0287. One L coordinates to Pt through the N atom whereas the other is in the zwitterionic form and coordinates through the O atom. The low reactivity of cis-[PtL2Cl2] in substitution reactions is explained on the basis of H bonding and agostic interactions due to which the axial positions in the square planar complexes are blocked against nucleophilic attack.
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Reference:
Tetrahydroisoquinoline – Wikipedia,
1,2,3,4-Tetrahydroisoquinoline | C9H11N – PubChem