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  Home > JCE Print > Journal of Chemical Education > Issues > 2005  > March  >
In the Laboratory
Crystallographic Study of Manganese(III) Acetylacetonate: An Advanced Undergraduate Project with Unexpected Challenges
Silvano Geremia and Nicola Demitri
Department of Chemical Sciences, Centre of Excellence in Biocrystallography, University of Trieste, 34127 Trieste, Italy
Cover
March 2005
Vol. 82 No. 3
p. 460
Abstract
An advanced undergraduate crystallographic experiment is proposed that integrates the well-tested protocol for synthesis of manganese acetylacetonate, Mn(acac)3, with a new low-temperature characterization of the crystal structure of the synthesized complex. Standard synthesis of Mn(acac)3 was followed by crystallization trials to obtain single crystals suitable for X-ray structural determination. Surprisingly, single crystals of a new crystalline form (δ) were obtained. When cooled to 100 K, single crystals of the δ form underwent an irreversible solid–solid phase transition to another new form (ε). The discovery of these new crystalline forms was a highly stimulating experience for the students involved. The goal to investigate the Jahn–Teller behavior of the high-spin Mn(III) complex, Mn(acac)3, was more than successfully achieved with the recognition of an unusual orthorhombic distortion (OD) of the coordination polyhedron. This experiment not only introduces crystallography, one of the most powerful techniques in chemistry, but, more importantly, it demonstrates that new experiments allow new knowledge to be gained with respect to that well established in the literature.
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Instructions for the students are available.
*  Contents JCE2005p0460W.doc (Microsoft Word)
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*  Citation
 Geremia, Silvano; Demitri, Nicola. J. Chem. Educ. 2005 82 460.
*  Keywords
 Coordination Chemistry; Crystallography / Crystal Growth; Laboratory Instruction; Molecular Properties / Structure; Organic Chemistry; X-ray Crystallography
*  History
 Created:
Last Updated:		 February 2, 2005
February 16, 2005
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