Structural and Magnetic Properties of M(mnt)2 Salts (M = Ni, Pt, Cu) with a Ferrocene-Based Cation, [FcCH2N(CH3)3]+. Interplay between M·
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- 作者：Anthony E. Pullen ; Christophe Faulmann ; Konstantin I. Pokhodnya ; Patrick Cassoux ; and Madoka Tokumoto
- 刊名：Inorganic Chemistry
- 出版年：1998
- 出版时间：December 28, 1998
- 年：1998
- 卷：37
- 期：26
- 页码：6714 - 6720
- 全文大小：148K
- 年卷期：v.37,no.26(December 28, 1998)
- ISSN：1520-510X
文摘
A series of metal bis-mnt complexes (mnt = 1,2-dithiolatomaleonitrile) with the trimethylammonium methylferrocene cation have been synthesized and characterized using X-ray diffraction, magnetic susceptibility, anddifferential scanning calorimetry measurements. The complexes have the formulas (FcCH2NMe3)[Ni(mnt)2] (2),(FcCH2NMe3)[Pt(mnt)2] (3), and (FcCH2NMe3)2[Cu(mnt)2] (4) (where Fc = ferrocene). At 300 K, the crystalstructures of 1:1 complexes 2 and 3 are very similar. They consist of pairs of [M(mnt)2]- in a slipped configurationpacked in stacks. Each [M(mnt)2]- stack is separated from adjacent stacks by two columns of cations. Within thepairs, the [M(mnt)2]- anions interact via short M···S contacts, while there are no short contacts between thepairs. Complex 4, which has a 2:1 stoichiometry, exhibits a markedly different packing arrangement of the anionicunits. Due to the special position of the Cu atom in the asymmetric unit cell, [Cu(mnt)2]2- dianions are completelyisolated from each other. The magnetic susceptibility behavior of the nickel complex is consistent with the presenceof magnetically isolated, antiferromagnetically (AF) coupled [Ni(mnt)2]- pairs with the AF exchange parameter,J = -840 cm-1. The platinum complex undergoes an endothermic structural phase transition (Tp) at 247 K.Below Tp its structure is characterized by the formation of magnetically isolated [Pt(mnt)2]22- dimers in an eclipsedconfiguration with short Pt···Pt and S···S contacts between monomers. In the magnetic properties, the structuralchanges reveal themselves as an abrupt susceptibility drop implying a substantial increase of the AF exchangeparameter. A mechanism of the phase transition in the platinum compound is proposed. For compound 4,paramagnetic behavior is observed.