Spectroscopic and computational studies on a new Pd(II)-bis(pyrazol-1-yl)methane aqua-complex

By reacting a stoichiometric amount of BPM or Me2BPM (BPM = bis(pyrazol-1-yl)methane, Me2BPM = bis(3,5-dimethylpyrazol-1-yl)methane) with Pd(OAc)2 (OAc = acetate) in CH2Cl2, the new neutral complexes [Pd(OAc)2(BPM)] (1) and [Pd(OAc)2(Me2BPM)] (1Me) were isolated and characterized by NMR and IR spectroscopy. Acidolysis of one Pd-OAc bond of compound 1 by using aqueous perchloric acid in methanol led to the formation of the stable cationic aqua-complex [Pd(OAc)(H2O)(BPM)](ClO4) (2-ClO4). The [Pd(OAc)(H2O)(BPM)]+ cation was obtained also by reacting 1 with trifluoromethanesulfonic acid. NMR studies on inter- and intra-molecular hydrogen bonding of the aqua-ligand have been carried out and the data obtained have been interpreted on the basis of the results of DFT calculations. © 2010 Elsevier B.V. All rights reserved.