Rhenium(I)-Pterin water-soluble complex: Synthesis and structural characterization. Two reversible protonation-deprotonation behavior in aqueous solutions.

RAGONE, F; RUIZ, G. T.; PIRO, O. E. ; ECHEVERRIA, G. V. ; F. M. CABRERIZO; G. PETROSELLI; ERRA BALSELLS, ROSA; K. HIRAOKA; F. GARCÍA EINSCHLAG ; E. WOLCAN

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2012 vol. 29

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 single crystals could be obtained for structural X-ray analysis. We report here the first solid state molecular structure containing a pterin ligand coordinated to the ‒Re(CO)3 core. This determination revealed that strong H-bonds between the hydrogen of the 2-amino group and crystallization water molecules give rise to a polymeric arrangement of Re(CO)3(pterin)(H2O) complexes in the lattice. Protonation studies in aqueous solutions of the Re(I) complex showed two acid-base equilibriums with pKa1= 3.9 and pKa2= 8.8. pKa1 was assigned to the protonation equilibrium at N3 of pterin ligand in the complex and pKa2 could be ascribed to the deprotonation of coordinated water molecule. 3(pterin)(H2O) complexes in the lattice. Protonation studies in aqueous solutions of the Re(I) complex showed two acid-base equilibriums with pKa1= 3.9 and pKa2= 8.8. pKa1 was assigned to the protonation equilibrium at N3 of pterin ligand in the complex and pKa2 could be ascribed to the deprotonation of coordinated water molecule.