Die Niob(V)‐ und Tantal(V)‐Komplexe von Acetylaceton und Brenzcatechin, ausgehend von den Pentamethylaten

Abstract

Abstract pH‐titrations in methanolic solutions (μ = 1, N(CH 3 ) 4 Cl, 20,0°) demonstrate that only 1:1 complexes are formed between Nb V or Ta V and acetylacetone (aa) The complexes Maa(OR) 2 2+ , Maa(OR) 3 + and Maa(OR) 4 (M = Nb, Ta; R = CH 3 ) are shown to exist. Stepwise complex formation takes place with pyrocatechol (bz), and the existence of the complexes Mbz(OR) 3 , Mbz(OR) 4 − , M 2 bz 2 (OR) 7 − , Mbz 2 (OR) 2 − and Mbz 3 OR 2− is established. The equilibrium constants of some of the complex forming reactions are evaluated. The new compounds Maa(OR) 4 , Maa(OR) 3 Cl, Tabz(OR) 3 , KTabz(OR) 4 , KTabz 2 (OR) 2 , K 2 Tabz 3 OR and M(OR) 4 Cl have been prepared.