Contact chemical shifts for the hydrogen atoms of nickel complexes of aromatic amines. Spin density distributions in naphthalene and anthracene derivatives. Spin density transmission through carbon, nitrogen, oxygen, and sulfur atoms

Abstract

Contact chemical shifts are reported for the hydrogen atoms in the aromatic ligands of the nickel acetylacetonate complexes of 1-and 2-aminonaphthalene, 1-and 2-aminoanthracene, 3-and 4-aminobiphenyl, 2-aminofluorene, 4-aminodiphenylmethane, 4-aminobenzophenone, 4-aminodiphenylamine, 4-aminodiphenyl ether, 4-aminodiphenyl thioether, and other selected compounds. The contact chemical shifts measure the relative effectiveness of the 7r electron systems in these molecules for the transmission of the spin density introduced through the amino substituent. The results for the naphthalenes and anthracenes are compared and contrasted with predictions based on other empirical and theoretical models. The results for the molecules with heteroatoms such as 4-aminodiphenylamine suggest that spin density is transmitted more effectively through the amino group than through the other atoms. Conformational factors can play a major role in the determination of the effectiveness of bridging groups for the transmission of spin density. The results for the molecules with bridging heteroatoms are also compared and contrasted with the results obtained in other studies.