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619366 
Journal Article 
Interactions of 1,5-naphthyridine with Pd(en)Cl2or [Pd(en)(H2O)2](NO3)2in aqueous solutionElectronic supplementary information (ESI) available: 1H NMR spectra of 2:1, 1:1, and 1:2 mole ratio of Pd(en)Cl2:1,5-NAP and pure 1,5-NAP; pH titration plot. See 
Shourong, Z; Karlos, XM; Roxanne, MJ; Judith, AW 
2008 
Yes 
Dalton Transactions
ISSN: 1477-9226
EISSN: 1477-9234 
2008 
45 
6401-6408 
The nature of the complexes formed in aqueous solution between either Pd(en)Cl2or [Pd(en)(H2O)2](NO3)2and 1,5-naphthyridine (1,5-NAP), where en is ethylenediamine, have been investigated by 1-D and 2-D 1H NMR spectroscopy and potentiometric titration. Above pH 5.0, two major complexes have been identified with the stoichiometries of 2:1 and 1:1 (M:L ratio) as well as small amounts of a 1:2 complex and/or oligomer. The 2:1 complex consisted of a Pd(en)2+moiety symmetrically bonded to each of the nitrogen atoms of the 1,5-NAP, as indicated by the presence of just three 1H NMR resonances in the aromatic region. The 1:1 complex had six resonances as a result of only one 1,5-NAP nitrogen atom being bonded to a Pd(en)2+group. At pH <5, the uncomplexed nitrogen of the 1:1 and other singly bonded 1,5-NAP species became protonated and resulted in the formation of a large number of complexes. Job's method plots at pH 6 showed that the 1:1 complex is stable over a large concentration range. Above pH ∼6 the 1:1 complex can dimerize viadeprotonation of a water ligand on the Pd(en)2+to form an hydoxo-bridged or oxo-bridged species. Evidence for this was observed in the upfield shifts of the resonances as the pH increased. The species distribution curve from potentiometric titrations and the NMR data were in good agreement at concentrations of 1–4 mM. NOESY data indicated that free 1,5-NAP ligand was exchanging with that in the 1:1 complex. In order to interpret the en region of the 1H NMR spectra, the spectra of [Pd(en)(H2O)2](NO3)2in D2O at various pD were obtained. [ABSTRACT FROM AUTHOR] Copyright of Dalton Transactions: An International Journal of Inorganic Chemistry is the property of Royal Society of Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts) 
COMPLEX compounds; PALLADIUM compounds; CHLORINE compounds; NUCLEAR magnetic resonance spectroscopy; HYDROGEN-ion concentration; VOLUMETRIC analysis; ETHYLENEDIAMINE; ETHER