Tetrahydrogendecavanadate(V) and its binding to glycylglycine

An adduct between the tetrahydrogen form of decavanadate H4V10O282- and gly cylglycine, with the stoichiometry Rb2H4V10O28 . 2Gly-Gly . 2H(2)O, has bee n isolated and fully characterized. The crystal structure has been determin ed hv X-ray diffraction data. The four hydrogen atoms of the polyvanadate f ramework could not be located directly, but structural features suggest str ongly that they are associated with two triply bridging and two doubly brid ging oxygens atoms. Two dipeptide molecules interact with the decavanadate polyanion via a hydrogen bond between O atoms of the carboxylic groups and a couple of doubly bridging surface atoms, which act as accepters, In addit ion, there are hydrogen bonding contacts in which the nitrogen atoms and th e carbonyl oxygen of the dipeptide molecules take part. IR spectroscopy pro ved useful in establishing the protonation state of Gly-Gly. (C) 1999 Publi shed by Elsevier Science S.A. All rights reserved.