pH dependent transformation of nitrilotriacetato molybdates (VI) – Synthesis, spectral and structural characterization

Investigation on the aqueous coordination chemistry of nitrilotriacetato molybdate (VI) resulted in the isolation of molybdenum(VI) nitrilotriacetato complexes Na6n{[Mo2O5(ntaH)2][(nta)2Mo2O5]}n · 12nH2O (1) and (NH4)3n[Mo2O5H(nta)2]n · 4nH2O (2) (H3nta = nitrilotriacetic acid). The complexes have been characterized by elemental analyses, IR, NMR spectroscopies and X-ray structural analyses. The anions of complexes 1 and 2 contain a linear (O2Mo)O(MoO2) core with the bridging oxo group lying at a center of symmetry. Each molybdenum atom is octahedrally coordinated by two terminal oxo groups, a bridging oxygen and a tridentate nitrilotriacetate ligand, which binds through the nitrogen atom and two μ-O carboxylates, while the other carboxylate remains free. Strong hydrogen bonds are found to exist in the two complexes. This is supported by IR and NMR spectra, and revealed by single crystal X-ray analysis. The complexes 1 and 2 show obvious decomposition in solution based on 13C NMR observations.

Very strong hydrogen bonds are found to exist in two hydrogen nitrilotriacetato molybdates (VI), which obviously decompose into the free ligand, based on 13C NMR observations.Figure optionsDownload as PowerPoint slide