The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Electronic structure and molecular association of some bis-(β-diketone)-nickel(II) complexes》. Authors are Fackler, J. P. Jr.; Cotton, F. A..The article about the compound:Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)nickel(II)cas:14481-08-4,SMILESS:CC(C)(C1=O[Ni+2]2(O=C(C(C)(C)C)[CH-]1)O=C([CH-]C(C(C)(C)C)=O2)C(C)(C)C)C).Computed Properties of C22H38NiO4. Through the article, more information about this compound (cas:14481-08-4) is conveyed.
Bis-(2,2,6,6-tetramethyl-3,5-heptanedione)-Ni(II) (I) is diamagnetic. Hydrocarbon solutions of I are red and have an absorption maximum at 535 mμ with a mol. extinction coefficient of 60. I forms a blue-green paramagnetic dihydrate. Bis(2,2-dimethyl-3,5-heptanedione)-Ni(II) (II) is paramagnetic, μeff. (297.4°K.) = 3.41 Bohr magnetons in the solid phase. Solutions of II in toluene have magnetic moments that are concentration and temperature dependent. The color of solutions of II changes from green near 0° to red at 50°, corresponding to an increase in absorption at 535 mμ. The paramagnetism in anhydrous β-diketone complexes of Ni(II) may be attributed to intermol. interactions, the monomers being diamagnetic. Thus the bulky tert-Bu groups in I prevent intermol. reactions and so anhydrous I is diamagnetic. In II interactions can take place and II is paramagnetic. Anhydrous bis-(3-phenyl-2,4-pentanedione)-Ni(II) (III) also is diamagnetic. Here the Ph group hinders interaction. III behaves similarly to II in toluene solution
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Reference:
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