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Ferrocenyl derivatives of [1,2,3]-diazaphosphole and [1,2,3]-diazaarsole

Authors: Kozáček Pavel | Dostál Libor | Růžička Aleš | Erben Milan

Year: 2019

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

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Language	Name	Abstract	Keywords
eng	Ferrocenyl derivatives of [1,2,3]-diazaphosphole and [1,2,3]-diazaarsole	Diazaphospholes constitute well-investigated class of heterocyclic compounds containing two nitrogen atoms, N(σ2,λ3) and N(σ3,λ3), together with one low-valent σ2,λ3-phosphorus atom incorporated in five-membered ring. On the other hand, study of diazaarsoles has much lesser extent and only a few derivatives are known up to now.1 This report describes the first representatives of ferrocene-substituted 2H-[1,2,3]-diazaphosphole and 2H-[1,2,3]-diazaarsole. The general synthetic method is based on the condensation of ferrocenylhydrazones with PCl3 or AsCl3 in the presence of trimethylamine, see Scheme 1. Direct synthesis of ferrocenyl-substituted 2H-diazaheteroles (R = H) from corresponding hydrazones fails and azine derivatives are formed as main product. Separation of ferrocenyl moiety with suitable bridging group (e.g. -C6H4-, -CMe2-) gives desired 2H-diazaheteroles, but azines are still present in the reaction mixture. To avoid this, and in order to prepare diazaheteroles with directly attached ferrocenyl substituent, 2-acetyl derivatives (R = Ac) have to be prepared at first. Subsequent deacetylation with phenylhydrazine or anhydrous hydrazine gives ferrocenyl-substituted 2H-[1,2,3]-diazaheteroles in moderate yields. The newly synthetized compounds have been characterized by multinuclear 1H, 13C and 31P NMR and vibrational spectroscopy. Molecular structures of several compounds have been determined by single-crystal X-ray diffraction analysis. The heterocyclic systems obtained by this manner could be promising metallo-ligands with a variety of coordination modes. It possesses different ligating sites and, after deprotonation, it can also serve as heteroaromatic analogue of cyclopentadienyl ligand.