Complexes cationiques POCOP de nickel : synthèse, caractérisation, réactivité et étude catalytique

Ce mémoire traite de la chimie des complexes pinceurs de nickel (II) cationiques ayant un ligand de type POCOP. Elle se divise en deux parties. La première traite de la synthèse, de la caractérisation et de la réactivité des complexes cationiques pinceurs de Ni(II) de type POCOP (POCOP = 1,3-bis(phosphinitobenzene), où C fait partie d’un cycle benzénique et est lié au métal, et P est un ligand phosphoré aussi lié au métal). Ces complexes ont un ligand acétonitrile coordonné au centre métallique et sont du type [(R-POCOPR’)Ni(NCMe)][OSO2CF3], où R est un substituant du cycle benzénique et R’ est un substituant sur le ligand phosphoré (R’ = iPr: R = H (1), p-Me(2), p-OMe(3), p-CO2Me(4), p-Br(5), m,m-tBu2(6), m-OMe(7), m-CO2Me(8); R’ = t-Bu : R = H (9), p-CO2Me(10)). Les complexes cationiques sont préparés en faisant réagir le dérivé Ni(II) neutre correspondant R-(POCOPR’)Ni-Br avec Ag(OSO2CF3¬) dans l’acétonitrile à température ambiante. L’impact des groupements R et R’ du ligand POCOP sur la structure et sur les propriétées électroniques du complexe a été étudié par spectroscopies RMN, UV-VIS et IR, analyse électrochimique, et diffraction des rayons X. Les valeurs de fréquence du lien C≡N (ν(C≡N)) augmentent avec le caractère électroattracteur du complexe, dans l’ordre 7 < 3 ~ 2 ~ 6 < 1 < 5 ~ 8 < 4 et 9 < 10. Ces résultats sont en accord avec le fait qu’une augmentation du caractère électrophile du centre métallique devrait résulter en une augmentation de la donation σ MeCN→Ni. De plus, les complexes cationiques montrent tous un potentiel d’oxydation Ni(II)/Ni(III) plus élevé que leurs analogues neutres Ni-Br. Ensuite, une étude d’équilibre entre un complexe neutre (R-POCOPR’)NiBr et un complexe cationique [(R-POCOPR’)Ni(NCMe)][OSO2CF3] démontre l’échange facile des ligands MeCN et Br. La deuxième partie de ce mémoire consiste en deux chapitres. Le premier (Chapitre 3) est une étude structurelle permettant une meilleure compréhension du mécanisme d’hydroamination des oléfines activées promue par les complexes présentés au chapitre 1, suivi de tentatives de synthèse de nouveaux composés POCOP cationiques comportant un ligand amine et nitrile, et de déplacement du groupement amine par un groupement nitrile. Le deuxième chapitre (4) décrit la réactivité et la cinétique de la réaction d’hydroamination et d’hydroalkoxylation d’oléfines activées, qui permet ainsi de mieux comprendre l’impact des différentes variables du système (groupements R et R’, température, substrats, solvent, etc.) sur la réactivité catalytique.

Raman spectroscopic characteristics of phthalocyanine and naphthalocyanine in sandwich-type phthalocyaninato and porphyrinato rare earth complexes Part 5. – Raman spectroscopic characteristics of naphthalocyanine in mixed [tetrakis(4-tert-butylphenyl)porphyrinato]-(naphthalocyaninato) rare earth double-deckers

Raman spectra were recorded in the range 400–1800 cm−1 for a series of 15 mixed \[tetrakis(4-tert-butylphenyl)porphyrinato](2,3-naphthalocyaninato) rare earth double-deckers M(TBPP)(Nc) (M = Y; La–Lu except Pm) using laser excitation at 632.8 and 785 nm. Comparisons with bis(naphthalocyaninato) rare earth counterparts reveal that the vibrations of the metallonaphthalocyanine M(Nc) fragment dominate the Raman features of M(TBPP)(Nc). When excited with radiation of 632.8 nm, the most intense vibration appears at about 1595 cm−1, due to the naphthalene stretching. These complexes exhibit the marker Raman band for Nc•− as a medium-intense band in the range 1496–1507 cm−1, attributed to the coupling of pyrrole and aza stretching, while the marker Raman band of Nc2− in intermediate-valence Ce(TBPP)(Nc) appears as a strong band at 1493 cm−1 and is due to the isoindole stretchings. By contrast, when excited with radiation of 785 nm that is in close resonance with the main Q absorption band of the naphthalocyanine ligand, the ring radial vibrations at ca 680 and 735 cm−1 for MIII(TBPP)(Nc) are selectively intensified and are the most intense bands. For the cerium double-decker, the most intense vibration also acting as the marker Raman band of Nc2− appears at 1497 cm−1 with contributions from both pyrrole CC and aza CN stretches. The same vibrational modes show weak to medium intensity scattering at 1506–1509 cm−1 for MIII(TBPP)(Nc) and this is the marker Raman band of Nc•− when thus excited. The scatterings due to the Nc breathings, ring radial vibration, aza group stretchings, naphthalene stretchings, benzoisoindole stretchings and the coupling of pyrrole CC and aza CN stretchings in MIII(TBPP)(Nc) are all slightly blue shifted along with the decrease in rare earth ionic radius, confirming the effects of increased ring–ring interactions on the Raman characteristics of naphthalocyanine in the mixed ring double-deckers.

Raman spectroscopic study of vivianites of different origins

Raman spectroscopy has been used to study a selection of vivianites from different origins. A band is identified at around 3480 cm-1 whose intensity is sample dependent. The band is attributed to the stretching vibration of Fe3+ OH units which are formed through the autooxidation of the vivianite minerals either by self-oxidation or by photocatalytic oxidation according to the reaction: (Fe2+)3(PO4)2·8H2O + 1/2O2 (Fe2+)3– x(Fe3+)x(PO4)2(OH)x·(8–x)H2O in which some of the water of crystallization is converted to hydroxyl anions. Complexity of the OH stretching region through the overlap of broad bands is reflected in the water HOH deformation modes at 1660 cm–1. Using the infrared bands at 3281, 3105 and 3025 cm–1, hydrogen bond distances of 2.734(5), 2.675(2) and 2.655(2) Å are calculated. Vivianites are characterised by an intense band at 950 cm–1 assigned to the PO4 symmetric stretching vibration. Low Raman intensity bands are observed at ~1077, ~1050, 1015 and ~ 985 cm–1 assigned to the phosphate PO4 antisymmetric stretching vibrations. Multiple antisymmetric stretching vibrations are due to the reduced tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Two bands are observed at ~ 423 and ~ 456 cm–1 assigned to the2bending modes. For the vivianites four bands are observed at ~ 584, ~ 571, ~ 545 and ~ 525 cm–1 assigned to the 4modes of vivianite.

Indoor exposure to submicrometer particles and PM2.5 in residential houses in Brisbane, Australia

As part of a large study investigating indoor air in residential houses in Brisbane, Australia, the purpose of this work was to quantify indoor exposure to submicrometer particles and PM2.5 for the inhabitants of 14 houses. Particle concentrations were measured simultaneously for more than 48 hours in the kitchens of all the houses by using a condensation particle counter (CPC) and a photometer (DustTrak). The occupants of the houses were asked to fill in a diary, noting the time and duration of any activity occurring throughout the house during measurement, as well as their presence or absence from home. From the time series concentration data and the information about indoor activities, exposure to the inhabitants of the houses was calculated for the entire time they spent at home as well as during indoor activities resulting in particle generation. The results show that the highest median concentration level occurred during cooking periods for both particle number concentration (47.5´103 particles cm-3) and PM2.5 concentration (13.4 mg m-3). The highest residential exposure period was the sleeping period for both particle number exposure (31%) and PM2.5 exposure (45.6%). The percentage of the average residential particle exposure level in total 24h particle exposure level was approximating 70% for both particle number and PM2.5 exposure.