Showing papers by "Helena I. S. Nogueira published in 2002"
TL;DR: Lower symmetry of the melamine molecule in the crystal has resulted in the decrease of intensity of the Raman active melamine band around 1490 cm(-1), and hydrogen bonding affects the ring breathing modes of melamine.
28 citations
TL;DR: In this paper, the new Pd(II), Pt(II, Re(V), Mo(VI), and W(VI) complexes of 2-hydroxynicotinic acid (H2nicO) have been prepared.
28 citations
TL;DR: In this article, the crystal structures of compounds with 2-mercaptonicotinic acid (HnicSH) were determined by X-ray diffraction, and the properties of these compounds were analyzed in infrared and 13C-{1H} NMR spectroscopy.
Abstract: New Pd(II), Pt(II), Re(III), Mo (VI) and Mo(V) complexes with 2-mercaptonicotinic acid (HnicSH), [Pd(PPh3)(HnicS)2]·0.5CH3OH 1, [Pd(HnicS)2]·CH3OH 2, [Pt(PPh3)(HnicS)2]·NEt3·H2O 3, [Pt(HnicS)2]
4, [Pt(bipy)(HnicS)2]·CH3OH 5, [Re(PPh3)(OCH3)(HnicS)2]
6, [ReI2(PPh3)2(HnicS)]
7, [MoO2(CH3NicS)2]
8 and [Mo2O3(CH3nicS)4]·DMF 9 have been prepared. The crystal structures of compounds 1, 3, 8 and [ReI2(PPh3)2(HnicS)]·0.5H2O·DMF (7·0.5H2O·DMF) were determined by X-ray diffraction. Complexes 1 and 3 contain two HnicS− ligands bonded in two different coordination modes: monodentate (S) and chelating (N,S). Complexes 7 and 8 contain only one HnicS− ligand which is bidentate (N,S). Infrared, 1H and 13C-{1H} NMR spectroscopic data for the complexes are presented. The Mo(VI) complex 8 is active towards oxygen atom transfer reactions and can catalyse the oxidation of benzoin and PPh3 with dmso; the catalysis occurs via the Mo(V) complex 9 which has been isolated and characterized.
17 citations
TL;DR: In this paper, a 2,2′-dithiodipyridine (2dtpy)-stabilized thin films stabilized by a methanol-toluene mixture were prepared and transferred to borosilicate glass slips by dip-coating.
Abstract: Silver nanostructured thin films stabilized by 2,2′-dithiodipyridine (2dtpy) were prepared. The Ag nanoparticles were obtained by treating the complex [Ag(2dtpy)]NO3 with NaBH4 in a methanol–toluene mixture. The films were transferred to borosilicate glass slips by a dip-coating method and were found to consist of Ag nanoparticles possibly linked via 2dtpy molecules. Surface-enhanced Raman scattering (SERS) studies have offered the possibility of investigating the adsorption modes of 2dtpy at the Ag nanoparticle surfaces in the films.
12 citations