Encapsulation of [Mn(bpy)b>3b>]²⁺ cations in 2D [Mn(dca)b>3b>]⁻ sheet: Synthesis, X-ray structure and EPR study

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• 作者：Dasarath Mal ; Subratanath Koner ; Jean-Pierre Tuchagues ; Georgina M. Rosair
• 关键词：Manganese(II) dca complex ; Crystal structure ; EPR spectroscopy ; Two-dimensional structure
• 刊名：Inorganica Chimica Acta
• 出版年：2007
• 期刊代码：40_00201693
• 类别：ch
• 出版时间：1 August 2007
• 卷：360
• 期：11
• 页码：3575-3580
• 文件大小：438 K

摘要

The reaction of Mn(NOb>3b>)b>2b> · 4Hb>2b>O, 2,2′-bipyridine (bpy) and sodium dicyanamide (dca) in aqueous medium yielded the b;[Mn(bpy)b>3b>][Mn(dca)b>3b>]b>2b>}b>nb> (1). The single-crystal X-ray analysis of 1 revealed that the anionic part of the complex, [Mn(dca)b>3b>]⁻, features infinite 2D sheets with a honeycomb-like porous structure having a void space of ca. 12 Å in which [Mn(bpy)b>3b>]²⁺ cations are encapsulated to yield a fascinating molecular assembly. Mn^II ions possess an octahedral geometry both in the anionic and cationic components of complex 1. In the anionic component, each Mn^II ion is bridged by three pairs of dicyanamide anions in an end-to-end fashion with two other Mn^II ions from adjacent [Mn(dca)b>3b>]⁻ moieties. This type of linking propagates parallel to the bc crystallographic plane to form 2D sheets. [Mn(bpy)b>3b>]²⁺ is found to have somewhat ȁc;squeezed” upon encapsulation. No measurable magnetic interaction was evidenced through variable temperature magnetic susceptibility measurements. However, in addition to the broad g ≈ 2 resonance typical of magnetically diluted [Mn(bpy)b>3b>]²⁺ cations, EPR spectroscopy evidenced exchange narrowing of the [Mn(dca)b>3b>]⁻ resonance at g ≈ 2 thus indicating operation of weak magnetic interactions extended over the whole 2D network through the dca⁻ bridges.