Electronic transitions as a probe of tetrahedral versus octahedral

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Carlos A. L. Filgueiras and Fernando Carazza Universidade Federal de Minas Gerais 30000 Belo Horizonte-MG Brasil

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Electronic Transitions as a Probe of Tetrahedral Versus Octahedral Coordination in Nickel(l1) Complexes An undergraduate inorganic chemistry experiment

T h e preparation of metal ion complexes with the same ion and different symmetries and the study of their electronic spectra can illustrate many different aspects of ligand field theory. If those complexes belong t o the two most important geometries, the tetrahedral and the octahedral cases, their study can be even more interesting and illustrative, especially if t h e experiments can he performed by the students themselves a t a n introductorv course on coordination chemistrv. Here we present such a scheme, involving t h e preparation of a tetrahedral nickel(I1) c o m ~ l e xand its transformation into a n octahedral speciks,' followed by a discussion of spectral results. ~~

Electronic Spectroscopy Figur? 1 show the spertra uf the fotrr-coordinate complex in ni~rumethnnennd acetonitr~le,2nd of the six-c