Water-soluble (Pterin)rhenium(I) complex: Synthesis, structural characterization, and two reversible protonation-deprotonation behavior in aqueous solutions

F. RAGONE; G. T. RUIZ; O. E. PIRO; G. A. ECHEVERRÍA; F. CABRERIZO; G. PETROSELLI; R. ERRA-BALSELLS; K. HIRAOKA ; F. GARCÍA EINSCHLAG ; E. WOLCAN

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2012 vol. 30 p. 4801 - 4810

1434-1948

A new water soluble complex, Re(CO)3(pterin)(H2O), was synthesized and characterized by 1H NMR, FTIR, and by a combination of three mass spectrometry techniques: MALDI, PESI and ESI. Due to the fact that, unlike most of the metal-pterin complexes, the Re(I) complex is quite soluble in water, appropriate crystals could be obtained for the X-ray analysis. This is the first time a crystal structure is obtained containing a pterin ligand coordinated to the -Re(CO)3 core. The structural characterization revealed that strong H-bonds between the hydrogen of the 2-amino group and crystallization water molecules gives rise to a polymeric arrangement linking neighboring Re(CO)3(pterin)(H2O) complexes that extends along the crystal c-axis. Protonation studies in aqueous solutions of the Re(I) complex showed two acid-base equilibriums with pKa 1= 3.9 and pKa2= 8.8.