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Synthesis and Sublimation Kinetics of a Highly Volatile Asymmetric Iron(II) Amidinate
Author(s) -
Li XinGui,
Li Zhengwen,
Li Huazhi,
Gordon Roy G.
Publication year - 2007
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200600960
Subject(s) - chemistry , thermogravimetric analysis , sublimation (psychology) , tetrahydrofuran , diethyl ether , activation energy , inorganic chemistry , organic chemistry , psychology , solvent , psychotherapist
Abstract A highly volatile asymmetric iron(II) amidinate, iron(II) bis( N ‐ tert ‐butyl‐ N′ ‐ethylacetamidinate), was synthesized for the first time by systematically changing starting iron(II) compounds such as acetylacetonate, acetate, and chloride, in different media such as diethyl ether, toluene, and tetrahydrofuran. The amidinate has been characterized and compared with the symmetric iron(II) bis( N , N′ ‐diisopropylacetamidinate) by NMR spectroscopy, MS, IR spectroscopy, and dynamic and isothermal thermogravimetric techniques. Different amidinates from three starting compounds exhibit almost the same NMR, MS, and IR spectra, a melting point of 85 °C, and the same solution color in the same solvents, but quite different synthetic yields, volatilities, and colors in different solvents. This implies that the amidinates show an interesting solvatochromism. In particular, the asymmetric iron(II) amidinates obtained should be a mixture of paramagnetic and diamagnetic compounds. The thermostability and sublimation kinetics of the iron(II) amidinates have been investigated in detail. It is found that the average activation energy of 106 kJ mol –1 for the nonisothermal sublimation is slightly higher than the average activation energy of 104 kJ mol –1 determined from the isothermal thermogravimetric experiments. The sublimation is a diffusion‐controlled process because the temperature and the rate of the sublimation depend strongly on the sublimation level and the sample size. The optimal iron(II) starting compound and reaction medium should be iron(II) acetylacetonate and diethyl ether, respectively, because the combination offers the highest yield, the greatest volatilizability of 98 %, and thus the purest product. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)