Structural Studies and Magnetic Properties of Polymeric Ladder-Type Compounds {Ln2[Ni(opba)]3}·S (Ln = Lanthanide Element; opba = o-Phenylenebis(oxamato), S = Solvent

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• 作者：Myrtil L. Kahn ; Pierre Lecante ; Marc Verelst ; Corine Mathoniè ; re ; and Olivier Kahn
• 刊名：Chemistry of Materials
• 出版年：2000
• 出版时间：October 2000
• 年：2000
• 卷：12
• 期：10
• 页码：3073 - 3079
• 全文大小：111K
• 年卷期：v.12,no.10(October 2000)
• ISSN：1520-5002

文摘

The compounds of formula {Ln₂[Ni(opba)]₃}·S (opba being o-phenelynebis(oxamato), Lnlanthanide^III ions, and S solvents molecules) have been structurally and magneticallycharacterized for Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, and Er. These compounds crystallizepoorly, and structural information has been obtained from EXAFS and wide-angle X-rayscattering (WAXS) techniques. The EXAFS studies have shown that the Ni site may adoptsquare planar geometry (with a spin S_Ni = 0) or octahedral geometry (with S_Ni = 1). Thecompounds are orange when the Ni sites are mostly square planar or green for Ni sitesmostly octahedral. The WAXS studies have shown that the compounds present the sameladder-like motif as that previously described for Tm₂[Cu(opba)]₃}·4H₂O·10DMF. Themagnetic properties of the compounds with magnetic octahedral Ni sites have been studiedand compared with those of the {Ln₂[Zn(opba)]₃}·S series for each Ln ion. This comparisonallows us to determine the nature of interactions in Ln^III-Ni^II pairs. It is clearly establishedthat the interaction is ferromagnetic when Ln^III is Gd^III, Tb^III, Dy^III, and perhaps Ho^III. Onthe contrary, the interaction seems to be antiferromagnetic for Ln^III = Ce^III, Pr^III, Nd^III, Er^III.These results are discussed with those obtained recently in Ln^III-Cu^II pairs.