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Title: Mandelohydroxamic acid as ligand for copper(II) 15-metallacrown-5 lanthanide(III) and copper(II) 15-metallacrown-5 uranyl complexes
Authors: Parac-Vogt, Tatjana ×
Pacco, Antoine
Nockemann, Peter
Yuan, Yao-Feng
Görller-Walrand, Christiane
Binnemans, Koen #
Issue Date: 2006
Publisher: Wiley-v c h verlag gmbh
Series Title: European journal of inorganic chemistry issue:7 pages:1466-1474
Abstract: The formation of pentanuclear copper(II) complexes with the mandelohydroxamic ligand was studied in solution by electrospray ionization mass spectrometry (ESI-MS), absorption spectrophotometry, circular dichroism and H-1 NMR spectroscopy. The presence of lanthanide(III) or uranyl ions is essential for the self-assembly of the 15-metallacrown-5 compounds. The negative mode ESI-MS spectra of solutions containing copper(II), mandelohydroxamic acid and lanthanide(III) ions (Ln = La, Ce, Nd, Eu, Gd, Dy, Er, Tm, Lu, Y) or uranyl in the ratio 5:5:1 showed only the peaks that could be unambiguously assigned to the following intact molecular ions: {Ln(NO3)(2)[15-MCuIIN(MHA)-5](2-)}(-) and {Ln(NO3)[15-MCCuIIN(MHA)-5](3-)}(-), where MHA represents doubly deprotonated mandelohydroxamic acid. The NMR spectra of the pentanuclear species revealed only one set of peaks indicating a fivefold symmetry of the complex. The pentanuclear complexes synthesized with the enantiomerically pure R- or S-forms of mandelohydroxamic acid ligand, showed circular dichroism spectra which were mirror images of each other. The pentanuclear complex made from the racemic form of the ligand showed no signals in the CD spectrum. The UV/ Vis titration experiments revealed that the order in which the metal salts are added to the solution of the mandelohydroxamic acid ligand is crucial for the formation of metallacrown complexes. The addition of copper(II) to the solutions containing mandelohydroxamic acid and neodymium(III) in a 5:1 ratio lead to the formation of a pentanuclear complex in solution. In contrary, titration of lanthanide(III) salt to the solution containing copper(II) and mandelohydroxamic acid did not show any evidence for the formation of pentanuclear species.
ISSN: 1434-1948
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Design and Synthesis
Chemistry - miscellaneous
× corresponding author
# (joint) last author

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