Three‐Dimensional Antiferromagnetic Order of Single‐Chain Magnets: A New Approach to Design Molecule‐Based Magnets |
| |
| Authors: | Hitoshi Miyasaka Prof. Karin Takayama Ayumi Saitoh Sachie Furukawa Masahiro Yamashita Prof. Rodolphe Clérac Dr. |
| |
| Affiliation: | 1. Department of Chemistry, Graduate School of Science, Tohoku University, 6‐3 Aramaki‐Aza‐Aoba, Aoba‐ku, Sendai, Miyagi 980‐8578 (Japan), Fax: (+81)?22‐795‐6548;2. Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1‐1 Minami‐ohsawa, Hachioji, Tokyo 192‐0397 (Japan);3. CNRS, UPR 8641, Centre de Recherche Paul Pascal (CRPP), Equipe “Matériaux Moléculaires Magnétiques”, 115 avenue du Dr. Albert Schweitzer, 33600 Pessac (France), Fax: (+33)?556‐84‐5600;4. Université de Bordeaux, UPR 8641, 33600 Pessac (France) |
| |
| Abstract: | Two one‐dimensional compounds composed of a 1:1 ratio of MnIII salen‐type complex and NiII oximato moiety with different counter anions, PF6? and BPh4?, were synthesized: [Mn(3,5‐Cl2saltmen)Ni(pao)2(phen)]PF6 ( 1 ) and [Mn(5‐Clsaltmen)Ni(pao)2(phen)]BPh4 ( 2 ), where 3,5‐Cl2saltmen2?=N,N′‐(1,1,2,2‐tetramethylethylene)bis(3,5‐dichlorosalicylideneiminate); 5‐Clsaltmen2?=N,N′‐(1,1,2,2‐tetramethylethylene)bis(5‐chlorosalicylideneiminate); pao?=pyridine‐2‐aldoximate; and phen=1,10‐phenanthroline. Single‐crystal X‐ray diffraction study was carried out for both compounds. In 1 and 2 , the chain topology is very similar forming an alternating linear chain with a [‐MnIII‐ON‐NiII‐NO‐] repeating motif (where ‐ON‐ is the oximate bridge). The use of a bulky counteranion, such as BPh4?, located between the chains in 2 rather than PF6? in 1 , successfully led to the magnetic isolation of the chains in 2 . This minimization of the interchain interactions allows the study of the intrinsic magnetic properties of the chains present in 1 and 2 . While 1 and 2 possess, as expected, very similar paramagnetic properties above 15 K, their ground state is antiferromagnetic below 9.4 K and paramagnetic down to 1.8 K, respectively. Nevertheless, both compounds exhibit a magnet‐type behavior at temperatures below 6 K. While for 2 , the observed magnetism is well explained by a Single‐Chain Magnet (SCM) behavior, the magnet properties for 1 are induced by the presence in the material of SCM building units that order antiferromagnetically. By controlling both intra‐ and interchain magnetic interactions in this new [MnIIINiII] SCM system, a remarkable AF phase with a magnet‐type behavior has been stabilized in relation with the intrinsic SCM properties of the chains present in 1 . This result suggests that the simultaneous enhancement of both intrachain (J) and interchain (J′) magnetic interactions (with keeping J ? J′), independently of the presence of AF phase might be an efficient route to design high temperature SCM‐based magnets. |
| |
| Keywords: | antiferromagnetism coordination chemistry low dimensionality magnetic properties single‐chain magnets |
|
|
