Controlling the Structure of Manganese(II) Phosphates by the Choice and Ratio of Organophosphate and Auxiliary Ligands |
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| Authors: | Ramaswamy Murugavel Prof Subramaniam Kuppuswamy Nayanmoni Gogoi Alexander Steiner Dr John Bacsa Dr Ramamoorthy Boomishankar Dr K G Suresh Prof |
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| Institution: | 1. Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai‐400076 (India), Fax: (+22)?2572‐3480, URL: http://www.chem.iitb.ac.in/～rmv/;2. Centre for Research in Nanotechnology and Science, Indian Institute of Technology Bombay, Powai, Mumbai‐400076 (India);3. Department of Chemistry, Crown Street, University of Liverpool, Liverpool, L69 7ZD (UK);4. Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai‐400076 (India) |
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| Abstract: | Tetranuclear manganese(II) phosphates Mn(dipp)(bpy)]4?4 H2O ( 1 ) and Mn4(dmpp)2(dmppH)4(bpy)4(H2O)2]?H2O ( 2 ) have been prepared from Mn(OAc)2?4 H2O and 2,6‐diisopropylphenyl phosphate (dippH2) or 2,6‐dimethylphenyl phosphate (dmppH2) in the presence of 2,2′‐bipyridine (bpy). In contrast, the reaction between Mn(bpy)2(OAc)(ClO4)]?H2O and dippH2 affords Mn(bpy)2(dippH)]2?2 ClO4?2 CH3OH ( 3 ). The reactions of Mn(OAc)2?4 H2O, dippH2, and pyridine (py) or 3,5‐dimethylpyrazole (dmpz) in CH3CN under reflux afford hexanuclear complexes Mn6(dipp)6(py)8]?2CH3CN ( 4 ) and Mn6(dipp)6(dmpz)6(AcOH)2]?2 H2O ( 5 ), respectively. Although compounds 1 and 2 are tetrameric, the former is a closed cubane‐like structure resembling the D4R secondary building unit of zeolites, whereas the latter exists in a staircase structure with fused Mn2O4P2 rings. The core structure of 3 contains a Mn2O4P2 eight‐membered ring that resembles the S4R building block of zeolites. Single‐crystal X‐ray diffraction studies reveal that compounds 4 and 5 have a similar core structure and differ from each other by the neutral ligands coordinated to manganese ions. All six phosphate ligands exist in a doubly deprotonated (RO)PO32?] form and exhibit two types of binding modes 5.222] and 3.111]. An interesting feature of compounds 1 – 5 is that although they are oligonuclear complexes, there is an absence of oxido bridges. The magnetic properties of compounds 1 – 5 have been investigated in the temperature range 5–298 K, and it was found that all the compounds obey the Curie law. |
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| Keywords: | coordination modes cubanes magnetic properties manganese phosphorus |
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