Niobium alcoholate clusters with an octahedral arrangement of metal atoms: [K(CH3OH)4]2 [Nb6(OCH3)18] and [Na([18]crown-6)(C2H5OH)2]2 [Nb6(OC2H5)12(NCS)6].

Complete exchange: [M(6)X(12)] type cluster compounds with an octahedral M(6) metal atom arrangement, which is completely surrounded by alcoholato ligands, were unknown until now. The first representatives are prepared containing a [Nb(6)(OR)(12)](4+) unit (R = CH(3) or C(2)H(5)). They are accessible at elevated temperatures from strongly basic alcoholate solutions of [Nb(6)Cl(12)](2+)-containing precursors. C gray, H white, K turquoise, Nb blue, O red.