Preparation and structure of K2[Nb2O2(μ-OH)2(nta)2]·4H2O — a complex of Nb(V) with a novel anti-{Nb2O2(μ-OH)2}4+ core

The reaction between Nb2S4aq4+ and K3nta (nta is nitrilotriacetate, N(CH2COO)33−), followed by slow oxidation in air, leads to complete desulfurisation of the starting Nb(IV) complex, oxidation of Nb(IV) to Nb(V) and crystallisation of the title complex with hitherto unknown [Nb2(O)2(μ-OH)2]4+ core. The crystal structure of the product has been determined.