New studies in the copper(II) acyclovir (acv) system. NMR relaxation studies and the X-ray crystal structure of [Cu(acv)(2)(H2O)(2)](NO3)(2)

The crystal structure of [Cu(acv)(2)(H2O)(2)] (NO3)(2) is reported; there i s a pseudo-chelate N(7)/O(6) bonding of a purine to the metal and it contai ns the shortest Cu-O(6) distance [2.698(2) Angstrom] so far reported for a simple copper(II)-nucleoside. This unusual bonding is due to the hydrophobi c medium (absolute methanol) used for crystallisation. H-1 NMR spectra of t he complex recorded both in methanol and in aqueous solution confirm N(7) a s the main copper coordination site and that the acyclic chain is not invol ved in binding. (C) 1998 Elsevier Science Ltd. All rights reserved.