932711-89-2Relevant academic research and scientific papers
O2-dependent aliphatic carbon-carbon bond cleavage reactivity in a Ni(II) enolate complex having a hydrogen bond donor microenvironment; comparison with a hydrophobic analogue
Grubel, Katarzyna,Fuller, Amy L.,Chambers, Bonnie M.,Arlf, Atta M.,Berreau, Lisa M.
, p. 1071 - 1081 (2010/05/15)
A mononuclear Ni(II) complex having an acireductone type ligand, and supported by the bnpapa (N,N-bis((6-neopentylamino-2-pyhdyl)methyl)-N-((2- pyridyl)methyl)amine) ligand, [(bnpapa)Ni(PhC(O)C(OH)C(O)Ph)]ClO4 (14), has been prepared and characterized by elemental analysis, 1H NMR, FTIR, and UV-vis. To gain insight into the1H NMR features of 14, the air stable analogue complexes [(bnpapa)Ni(CH3C(O)CHC(O)CH 3)]ClO4 (16) and [(bnpapa)Ni(ONHC(O)CH3)] ClO4 (17) were prepared and characterized by X-ray crystallography, 1H NMR, FTIR, UV - vis, mass spectrometry, and solution conductivity measurements. Compounds 16 and 17 are 1:1 electrolyte species in CH 3CN. 1H and 2H NMR studies of 14, 16, and 17 and deuterated analogues revealed that the complexes having six-membered chelate rings for the exogenous ligand (14 and 16) do not have a plane of symmetry within the solvated cation and thus exhibit more complicated 1H NMR spectra. Compound 17, as well as other simple Ni(II) complexes of the bnpapa ligand (e.g., [(bnpapa)Ni(ClO4)(CH3CN)]ClO4 (18) and [(bnpapaNi)2(μ-Cl)2](ClO4)2 (19)), exhibit 1H NMR spectra consistent with the presence of a plane of symmetry within the cation. Treatment of [(bnpapa)Ni(PhC(O)C(OH)C(O)Ph)] ClO4 (14) with O2 results in aliphatic carbon-carbon bond cleavage within the acireductone-type ligand and the formation of [(bnpapa)Ni(O2CPh)]ClO4 (9), benzoic acid, benzil, and CO. Use of 18O2 in the reaction gives high levels of incorporation (>80%) of one labeled oxygen atom into 9 and benzoic acid. The product mixture and level of 18O incorporation in this reaction is different than that exhibited by the analogue supported the hydrophobic 6-Ph2TPA ligand, [(6-Ph2TPA)Ni(PhC(O)C(OH)C(O)Ph)]ClO 4 (2). We propose that this difference is due to variations in the reactivity of bnpapa- and 6-Ph2TPA-ligated Ni(II) complexes with triketone and/or peroxide species produced in the reaction pathway.
