Arsoles transition metal complexes

Arsenic-containing heterocyclic derivatives are multifunctional ligands. For example, arsole can form several types of complexes (a) one involving the lone electron pair on As (156), (b) as a two-electron donor to one metal atom and, at the same time, as a one-electron donor to the other transition element (157), (c) as a four-electron ligand of the 7t-butadiene type due to the presence of two double C=C bonds (158), and (d) as a five-electron elementacyclopentadienyl ligand (159-162). Each of these types of compounds have been characterized by mass spectrometry (Tables 9 and 10). Unfortunately a detailed discussion of their mass spectral behaviour is unavailable. 

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