Synthesis and characterization of a series of N3O-ligated mononuclear Mn(II) halide complexes
作者:Amy L. Fuller、Rex W. Watkins、Atta M. Arif、Lisa M. Berreau
DOI:10.1016/j.ica.2005.09.008
日期:2006.3
Treatment of a N3O-donor chelate ligand (mpppa=N-methyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylethyl)amine; bpppa = N-benzyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylmethyl)amine) with equimolar amounts of Mn(ClO4)(2) center dot 6H(2)O and Me4NX (X = Cl, Br, 1) in methanol resulted in the production of a series of mononuclear Mn(H) halide complexes of the formula [(L)Mn-X(CH3OH)]ClO4 (L = mpppa or bpppa). X-ray crystallographic studies of [(mpppa)Mn-Cl(CH3OH)]ClO4 center dot CH3OH (2 center dot CH3OH), [(mpppa)Mn-Br(CH3OH)]ClO4 center dot CH3OH (4 center dot CH3OH), [(mpppa)Mn-I(CH3OH)]ClO4 center dot CH3OH (6 center dot CH3OH), and [(bpppa)Mn-I(CH3OH)]ClO4 center dot O-2(CH2CH3)(2) (7 center dot O(CH2CH3)(2)) revealed for each a mononuclear Mn(II) center having tetradentate coordination of the chelate ligand, one coordinated halide anion, and one molecule of coordinated methanol. An increase in the Mn-X distance through the halide series (Cl, Br, 1) correlates linearly with the increase in the radius of the anion. The magnetic moment of each halide complex, measured via Evans method in methanol, is consistent with the presence of a high-spin distorted octahedral Mn(11) center. The EPR features of the halide complexes in methanol do not change as a function of the nature of the halide coordinated to the Mn(II) center. (c) 2005 Elsevier B.V. All rights reserved.