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Stereochemistry of β-diketone complexes of cobalt(III)—V

1971; Pergamon Press; Volume: 33; Issue: 5 Linguagem: Inglês

10.1016/0022-1902(71)80432-3

1878-1225

L. J. Boucher, E.J. Battis, Nyole G. Paez,

Magnetism in coordination complexes

Proton magnetic resonance spectra of several mono and bis(β-diketone)cobalt(III) complexes have been measured and the chemical shifts of the methyl and methine protons determined. The complexes examined included: [Co en2dik]2+ where dik equal substituted acetylacetonate anions; cis and trans[Co acac2NO2L] where L equal alkylamines and substituted pyridines; and cis and trans[Co acac2L2]+(−) where L2 equal bidentate amines, ammonia and nitrite ion. The variation in chemical shift with the various ligands was several times greater for the methine than for methyl protons. The large variation in chemical shift with β-diketone substituent can be related to inductive effects and magnetic shielding effects. The much smaller variation of the chemical shift with other ligands can be rationalized by invoking magnetic anisotropy effects of the ligands. Electric field and cis and trans effects were found to be small.