NDLI: Microwave and traditional solvothermal syntheses, crystal structures, mass spectrometry and magnetic properties of $Co^{II}_{4}O

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Zhang, Kun Zeng, Ming-hua Dai, Jun Wang, Yun-hong Kurmoo, Mohamedally
Description	Author Affiliation: Zhang K ( Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Northwest University, Xi'an, 710069, PR China.)
Abstract	We report a study of the comparative solvothermal syntheses, using traditional and microwave ovens, of two complexes $[Co_{4}(μ_{3}-OMe)_{4}(L)_{4}(MeOH)_{4}],$ where (HL = Hhmb, 2-hydroxy-3-methoxy-benzaldehyde (1) or Hheb = 2-hydroxy-3-ethoxy-benzaldehyde (2)), their crystal structures and magnetic properties in the solid state and the ESI-MS of the solutions. The microwave heating is more efficient in time and quality of crystals than the traditional one where what is achieved per minute by the former takes an hour by the latter. The structures consist of stacks of high-symmetry $[Co_{4}(μ_{3}-OMe)_{4}]$ cubanes in tetragonal space groups. The inner cores of the clusters have almost the same geometry but the distances between them are longer for the ethoxy than the methoxy derivative. The magnetic interaction within the cluster is ferromagnetic in both cases but spin–orbit competes with it. The different isothermal magnetizations at low temperatures may be due to different intercluster coupling. Electrospray ionization mass spectrometry ( ESI-MS ) from methanol solution reveals an exchange of methoxide for hydroxide and in ethanol of methoxide for ethoxide at different proportions suggesting a probable “step by step” substitution. Interestingly, besides the $[Co_{4}]$ cubane a number of higher nuclearity species $[Co_{5}]$ and $[Co_{7}]$ were also observed but are not expected under electrospray conditions. This can easily happen by the re-assembly of the smaller fragments produced by ionization process. This unique feature opens up new possibilities for the systematic screening of reactions in search for new cluster architectures, which may then be realised in the solid state.
ISSN	14779226
Issue Number	15
Volume Number	42
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2013-04-21
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Cobalt Chemistry Microwaves Oxides Coordination Complexes Chemical Synthesis Crystallography, X-Ray Magnetics Methanol Molecular Conformation Spectrometry, Mass, Electrospray Ionization Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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