New amino-acid complexes of molybdenum-(V) and -(VI)

Abstract

Anions of the amino-acids iminodiacetic acid, N-methyliminodiacetic acid, nitrilotriacetic acid, aspartic acid, and histidine behave as tridentate ligands towards molybdenum(VI). In neutral solution they give complexes whose compositions and i.r. spectra show them to contain a MoO₃ core. The spectra of the corresponding molybdenum(V) complexes obtained at pH 5.5 point to the presence of a di-µ-oxo-dioxo Mo₂O₄ core. The glycinatomolybdenum(VI) complex is of the type[MoO₂(GlyO)₂] with two bidentate ligands. At pH 6, uramil-NN-diacetate is tridentate towards Mo^V and Mo^VI, but at pH 2 it co-ordinates to Mo^VIO₂ core in a quadridentate manner through the additional use of a carbonyl group of the ureide ring.