Yttrium(III) and lanthanide(III) perchlorate complexes with the 2,2,6,6- tetramethylpiperidine nitroxide free radical |
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Authors: | Chester M Mikulski Larry S Gelfand Louis L Pytlewski John S Skryantz Nicholas M Karayannis |
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Institution: | (1) Department of Chemistry and Physics, Beaver College, 19038 Glenside, Pa., USA;(2) Department of Chemistry, Drexel University, 19104 Philadelphia, Pa., USA;(3) Amoco Chemicals Corporation, 60540 Naperville, II, USA |
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Abstract: | Summary 2,2,6,6-Tetramethylpiperidine nitroxide free radical (TMPNO) complexes with Y3+ and Ln3+ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er or Yb) perchlorates were synthesized and characterized by means of i.r. and e.s.r. spectral, magnetic susceptibility and molar conductance studies. The new complexes are of the general type M(TMPNO-)2(OH2)3(OCIO3)](ClO4)2 (M = Y or Ln), involving two TMPNO;, three aqua and one unidentate perchlorato ligand in the complex cation, and two anionic C104 groups. The NO bond-order in coordinated TMPNO is apparently two, as suggested by the i.r. evidence. The magnetic susceptibility and e.s.r. data were interpreted in terms of partial spin-spin coupling interaction between the unpaired electrons of the two TMPNO- ligands, as well as unpaired f electrons, in the case of paramagnetic lanthanide(Ill) ions. Severe steric hindrance, introduced during coordination of the free radical ligand through the NO oxygen atom, does not seem to allow accommodation of more than two TMPNO molecules in the inner coordination sphere of the central Y3+, or Ln3+ ion.To whom all correspondence should be directed. |
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