摘要:

Progressing in the study of magnetic interacting bimetallic systems, we present here an analysis of the magnetic behavior of the compounds Cu3[M(cdta)]2(OH2)8(NO3)2⋅7H2O(cdta is trans‐1,2‐diamine‐NNN’N’‐tetra‐acetate; M=Cu, Ni; in short, [Cu3M2]). These compounds show a novel and exotic structural arrangement. There are three different coordination positions for the metals: an octahedral‐cdta‐chelating one (Oc), which can be occupied by Cu or Ni cations, and two more, mainly hydrated, but involving oxygen atoms from the carboxylate groups of the cdta. The first of them shows square–pyramidal and the second one square‐planar topology, SP and SC, respectively, and both are always occupied by copper cations. The connectivity among these units, leading to the chains, is warranted by the cdta‐oxygen atoms, and can be described by the sequence ‐[Oc‐(SP)2‐Oc‐SC]. TheXmT‐vs‐Tproduct for the [Cu3Cu2] compound shows a significant decrease when cooling down, which shows the presence of antiferromagnetic interactions. In the case of the [Cu3Ni2] compound, it also decreases when cooling down, but reaches a minimum atT=15 K, increases reaching a maximum atT=7 K, and then goes down suddenly. These behaviors will be discussed and magnetostructural correlations will be stablished.

ISSN:0021-8979    

DOI:10.1063/1.346050

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The crystal structure and magnetic susceptibility of a series of [M(en)3]3+(M=Cr or Co) derivatives are described. In particular, the crystalline structures of (1) [Cr(en)3]3[FeCl6]Cl6⋅H2O, (2) [Co(en)3]3[FeCl6]Cl6⋅H2O, and (3) [Cr(en)3][FeCl6]⋅11H2O are reported. Structural data, in A˚, for these compounds are as follows: (1) space groupR3,a=15.447(4),c=21.060(6),Z=3; (2) space groupR3,a=15.346(3),c=20.880(5),Z=3; (3) space groupP3c1,a=11.654(3),c=15.508(4),Z=2. The main structural feature of the first two isomorphous materials is that they consist of a three‐dimensional network of triangular antiprisms formed by the [M(en)3]3+(M=Cr or Co) ions and connected with each other by sharing corners. An [FeCl6]3−ion is placed at the center of each antiprism. Compound (3) contains a sc arrangement of [Cr(en)3]3+and [FeCl6]3−octahedra. In addition, the magnetic susceptibilities of the above‐mentioned isomorphous compounds and of [M(en)3][FeCl6] (M=Cr and Co) and [Cr(en)3][InCl6] are reported. While [Cr(en)3]3[FeCl6]Cl6⋅H2O orders as a ferrimagnet at 0.91 K, [Cr(en)3][FeCl6] exhibits antiferromagnetic properties withTc=2.26 K, a temperature rather similar to the antiferromagnetic ordering temperature of [Co(en)3][FeCl6].

ISSN:0021-8979    

DOI:10.1063/1.346051

出版商:AIP    

年代:1990

数据来源: AIP