Coinage metal complexes with metastable selenium
The aim of our work is to elucidate the possibility to obtain up to now unknown selenium modifications in such complexes. Well known allotrope modifications of selenium consists of chains (Se∞) and rings like Se6, Se7 and Se8. A few of them are stabilized in transition metal complexes like PdCl2Se6[5], PdBr2Se6[5], Re2I2(CO)Se7[6] and (AgI)2Se6[7]
We succeeded in the stabilization of new metastable allotropic modifications like Se6, Se12 and Se19 in weakly bound coinage metal complexes
[Ag2Se12][Al(OC(CF3)3)4]2
[Cu2Se12][Al(OC(CF3)3)4]2
Such rings appear to form only dicationic complexes, whereas sulfur modifications exist in monocationic complexes only. A higher charge seems to be necessary in order to avoid the thermodynamically favored polymerization to the grey stable selenium modification.
Thus these results give confidence for the prospective synthesis of unknown modifications.
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