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Relevant bibliographies by topics / Pi-acceptor and sigma-donor ligands

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Academic literature on the topic 'Pi-acceptor and sigma-donor ligands'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 February 2022

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Journal articles on the topic "Pi-acceptor and sigma-donor ligands"

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Maqsood, Syed Raashid, Nasarul Islam, Shabnum Bashir, Badruddin Khan, and Altaf Hussain Pandith. "Sigma donor and pi acceptor characteristics of certain NN-bidentate ligands: a DFT Study." Journal of Coordination Chemistry 66, no. 13 (2013): 2308–15. http://dx.doi.org/10.1080/00958972.2013.800866.

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Fielder, Scott S., Mark C. Osborne, A. B. P. Lever, and William J. Pietro. "First-Principles Interpretation of Ligand Electrochemical (EL(L)) Parameters. Factorization of the .sigma. and .pi. Donor and .pi. Acceptor Capabilities of Ligands." Journal of the American Chemical Society 117, no. 26 (1995): 6990–93. http://dx.doi.org/10.1021/ja00131a022.

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Lui, S. M., A. Soriano, and J. A. Cowan. "Electronic properties of the dissimilatory sulphite reductase from Desulfovibrio vulgaris (Hildenborough): comparative studies of optical spectra and relative reduction potentials for the [Fe4S4]-sirohaem prosthetic centres." Biochemical Journal 304, no. 2 (1994): 441–47. http://dx.doi.org/10.1042/bj3040441.

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The dissimilatory sulphite reductase (desulfoviridin) from the sulphate-reducing bacterium Desulfovibrio vulgaris (Hildenborough) displays distinct optical and redox characteristics relative to the haem subunit of Escherichia coli assimilatory sulphite reductase. For high-spin pentaco-ordinate desulfoviridin there is minimal change in the absorbance of the oxidized chromophores both after reduction or after addition of exogenous ligands. A ligand-metal charge-transfer band approximately 702 nm is observed in both the oxidized and one-electron-reduced enzyme. E.p.r. spectroscopy has been used to define the relative reduction potentials for sirohaem and [Fe4S4] centres (delta E0 = Es0-Ec0) as a function of sirohaem axial co-ordination. Typically delta E0 lies in a range from -10 to -50 mV. These results show a correlation with the sigma-donor or pi-acceptor properties of the ligand and stand in sharp contrast with estimates for the E. coli enzyme. The electronic properties of the coupled [Fe4S4]-sirohaem redox centre common to both nitrite- and sulphite-reducing enzymes are apparently strongly dependent on the environment generated by protein side chains.

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Rahman, M. Matiur, Hong Ye Liu, Klaas Eriks, Alfred Prock, and Warren P. Giering. "Quantitative analysis of ligand effects. Part 3. Separation of phosphorus(III) ligands into pure .sigma.-donors and .sigma.-donor/.pi.-acceptors. Comparison of basicity and .sigma.-donicity." Organometallics 8, no. 1 (1989): 1–7. http://dx.doi.org/10.1021/om00103a001.

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Wayland, Bradford B., Alan E. Sherry, and Andrew G. Bunn. "EPR studies of 1:1 complexes of rhodium(II) and cobalt(II) porphyrins with .sigma. donor and .pi. acceptor ligands: origins of rhodium(II) metalloradical reactivity." Journal of the American Chemical Society 115, no. 17 (1993): 7675–84. http://dx.doi.org/10.1021/ja00070a011.

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Hazari, Arijit Singha, Alexa Paretzki, Jan Fiedler, Stanislav Zalis, Wolfgang Kaim та Goutam Kumar Lahiri. "Different manifestations of enhanced π-acceptor ligation at every redox level of [Os(9-OP)L2]n, n = 2+, +, 0, − (9-OP− = 9-oxidophenalenone and L = bpy or pap)". Dalton Transactions 45, № 45 (2016): 18241–51. http://dx.doi.org/10.1039/c6dt03764j.

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Bedard, Robert L., and Lawrence F. Dahl. "Electrochemical analysis of biocapped triangular cobalt cyclopentadienyl clusters, [Co3(.eta.5-C5H5-xMex)3(.mu.3-X)(.mu.3-Y)]n (x = 0, 1, 5), containing mixed .pi.-acceptor X and .pi.-donor Y capping ligands [X = CO, NO; Y = NSiMe3, NC(O)NH2, NH]: pronounced variations in redox behavior as a function of coordinating ligands." Journal of the American Chemical Society 108, no. 19 (1986): 5933–42. http://dx.doi.org/10.1021/ja00279a044.

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Nardo, Luca, Maria Bondani, and Alessandra Andreoni. "Discrimination of the binding mode of DNA ligands by single-photon timing." Spectroscopy 23, no. 1 (2009): 11–28. http://dx.doi.org/10.1155/2009/605756.

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We perform time-correlated single-photon counting measurements with 30-ps resolution of the fluorescence emitted by the donor fluorophores of donor–acceptor pairs covalently labeling DNA synthetic oligonucleotides by using a non-commercial single-photon avalanche diode. The measurements allow us to precisely assess the fluorescence resonant energy transfer efficiency of the pairs in solutions containing the oligonucleotides and DNA–ligands, for different ratios of the DNA base-pair to ligand concentrations. A quantitative evaluation of the deformations of DNA double strands following the ligand binding is obtained, as the transfer efficiency is a steep function of the donor-to-acceptor distance. The results lead to an easy and cheap method to discriminate between the binding modes of minor groove and base intercalating ligands.

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Martínez-Prieto, L. M., I. Cano, A. Márquez, et al. "Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts." Chemical Science 8, no. 4 (2017): 2931–41. http://dx.doi.org/10.1039/c6sc05551f.

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Pt NPs covered with zwitterionic amidinates as ligands exhibit an exciting ligand effect in the hydrogenation of carbonyl groups when electron donor/acceptor groups are introduced in theN-substituents.

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Cameron, Lindsay A., Joseph W. Ziller, and Alan F. Heyduk. "Near-IR absorbing donor–acceptor ligand-to-ligand charge-transfer complexes of nickel(ii)." Chemical Science 7, no. 3 (2016): 1807–14. http://dx.doi.org/10.1039/c5sc02703a.

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Dissertations / Theses on the topic "Pi-acceptor and sigma-donor ligands"

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Silva, Camila Fontes Neves da. "Investigação comparativa da liberação controlada de CO e NO por carboxilatos trinucleares de rutênio contendo ligantes pi-receptor e sigma-doador." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-23052015-113643/.

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Neste trabalho foram realizadas as sínteses e caracterizações dos precursores (1) [Ru3O(CH3COO)6(CH3OH)3]CH3COO, (2) [Ru3O(CH3COO)6(CO)(CH3OH)2] (3) [Ru3O(CH3COO)6(4-acpy)2(H2O)]PF6, (4) [Ru3O(CH3COO)6(4-tbpy)2(H2O)]PF6 e dos complexos inéditos (5) [Ru3O(CH3COO)6(4-acpy)2(CO)], (6) [Ru3O(CH3COO)6(4-tbpy)2(CO)], (7) [Ru3O(CH3COO)6(4-acpy)2(NO)]PF6, (8) [Ru3O(CH3COO)6(4-tbpy)2(NO)]PF6. Os complexos foram caracterizados por espectroscopia na região do UV-Vis e do infravermelho, espectroscopia de ressonância magnética nuclear (RMN), voltametria cíclica e análise elementar. Por meio dos resultados obtidos nas técnicas de caracterização, foi possível confirmar a estrutura proposta inicialmente para os complexos e também para os precursores. Além disso, também foi possível observar a influência dos ligantes, -receptor e -doador na estrutura dos mesmos. Por meio da técnica de espectroscopia de infravermelho analisou-se principalmente estiramentos dos ligantes CO nos complexos 5 e 6 e do NO nos complexos 7 e 8. Nos estudos de RMN observou-se as características diamagnéticas dos complexos 5 e 6, e no caso dos complexos 7 e 8 foi possível confirmar que há uma forte interação entre o elétron desemparelhado na unidade [Ru3O]+ e do ligante NO0. Os ensaios eletroquímicos de voltametria cíclica mostraram a influência dos ligantes CO e NO na comunicação eletrônica da unidade [Ru3O].Os complexos com ligantes CO e NO foram irradiados com laser em 377 nm e 660 nm em soluções de acetonitrila e tampão fosfato pH 7,4. Estas irradiações foram acompanhadas por espectroscopia na região do UV-visível. No caso dos complexos 5 e 6, o aumento da banda na região de 900 nm indicou a formação do complexo, [Ru3O(CH3COO)6(L)2(S)], após a liberação do ligante monóxido de carbono (CO). A liberação de CO ocorreu predominantemente com irradiação em 377 nm na região do ultravioleta em pH fisiológico (solução aquosa de tampão fosfato, pH=7,4) e também em solução de acetonitrila. Para os complexos com ligantes NO, o perfil espectral obtido após fotólise indicou a formação de um complexo oxidado sem a coordenação do NO, [Ru3O(CH3COO)6(L)2(S)]+.<br>In this study it was performed the synthesis and characterization of the precursors (1) [Ru3O(CH3COO)6(CH3OH)3]CH3COO, (2) [Ru3O(CH3COO)6(CO)(CH3OH)2] (3) [Ru3O(CH3COO)6(4-acpy)2(H2O)]PF6 (4) [Ru3O(CH3COO)6(4-tbpy)2(H2O)]PF6 and the unpublished complexes (5) [Ru3O(CH3COO)6(4-acpy)2(CO)] (6) [Ru3O(CH3COO)6(4-tbpy)2(CO)] (7) [Ru3O(CH3COO)6(4-acpy)2(NO)]PF6 (8) [Ru3O(CH3COO)6(4-tbpy)2(NO)]PF6. The complexes were characterized by UV-Vis and infrared spectroscopy, nuclear magnetic resonance (NMR), cyclic voltametry, and elemental analysis. By means of the results obtained from the characterization, it was possible to confirm the initially proposed structure for both complexes and precursors. Furthermore, it was also possible to observe the influence of ligands, - receptor and the -donor in the structure of the complexes. By infrared spectroscopy it was verified primarily stretches of the CO and NO ligands in complexes 5,6 and 7,8 respectively. In NMR it was observed the diamagnetic character of complexes 5 and 6, and in the case of complexes 7 and 8 it was confirmed that there is a strong interaction between the unpaired electron in the [Ru3O]+ unit and the NO0 ligand. The cyclic voltammograms showed the influence of the CO and NO ligands on the electronic communication of the [Ru3O] unit. Complexes with ligands CO and NO were irradiated with laser at 377 nm and 660 nm in solutions of acetonitrile and phosphate buffer pH 7.4. The photolysis were accompanied by spectroscopy in the UV-visible region. In the case of complexes 5 and 6, the increase of the band in the region of 900 nm indicated the formation of the complex, [Ru3O(CH3COO)6(L)2(S)]+ produced after release of carbon monoxide (CO). The release of CO occurs predominantly with irradiation at 377 nm in the ultraviolet region at physiological pH (aqueous phosphate buffer solution, pH = 7.4) and in acetonitrile solution. For complexes with NO ligands, the spectral profile obtained after photolysis indicated the formation of an oxidized complex without coordination of NO, the [Ru3O(CH3COO)6(L)2(S)] + molecule.

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El, hellani Ahmad. "Evaluation of The Electronic Properties of Carbon(0)-Based Compounds Through Gold Catalysis and X-Ray Structure Analysis." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112252.

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La plupart des composés organiques ont un atome de carbone tétravalent, où tous les électrons de valence sont utilisés pour former des liaisons covalentes. En parallèle, la chimie des composés divalents ayant un carbone(II) s’est développée après l’isolement de carbènes stables par Bertrand en 1985. Auparavant, en 1961, Ramirez a rapporté l’isolement de l’hexaphénylcarbodiphosphorane, que l’on peut considérer comme un composé présentant un carbone(0) avec ses deux doublets libres, lui permettant de coordiner jusqu’à deux acides de Lewis. A partir de 2006, les propriétés électroniques de ces ligands ont été étudiées au travers d’études théoriques par Frenking ; ce qui a permis à Bertrand et Fürstner d’isoler et d’ajouter des nouveaux membres à cette famille. Cette classe de ligand est aujourd’hui connue sous le nom de “carbônes”, avec comme formule générale CL2 (L = PR3 ou carbène).Cette famille n’a jamais été utilisée dans le domaine de la catalyse. C’est pourquoi nous avons, décidé d’etudier les propriétés électroniques de ce ces composés au travers de la catalyse à l’or, afin de les comparer aux NHC, phosphines, et phosphites. Récemment, nous avons utilisé ces composés pour générer des complexes donneur accepteur avec du GaCl3, et de corréler leurs différentes caractéristiques géometriques à leurs propriétés électroniques en utilisant les règles de Gutmann sur des adduits acide/base de Lewis. De plus, nous avons isolé des “dimères” ioniques dont la formation peut être expliquée par les propriétés intrinsèques des ligands. Nous avons ainsi démontré par ces deux approches que les “carbônes” sont de meilleurs donneurs que les NHC<br>Most organic compounds which are stable in the condensed phase contain tetravalent carbon atoms, where all four valence electrons are being engaged in chemical bonds. On the other hand, the chemistry of divalent carbon(II) was only recognized after the isolation of a stable persistent carbene by Bertrand and co-workers in 1985. Such products display one s-type lone pair orbital and are thus good ligands. Earlier on, concern was also paid to a new family of compounds, first reported in 1961 by Ramirez and co-workers. They can be considered as divalent carbon(0) derivatives with two lone pairs at the central carbon, with a possibility of double coordination of two Lewis acids to this carbon. This feature was proposed by Kaska in 1973, and verified later by the isolation of di-metalated adducts. From 2006, these compounds were the centre of extensive theoretical investigations by Frenking, which led to the isolation of new members of this family by Fürstner and Bertrand. This family is now referred to as “carbones”, of general formula CL2 (L =PR3 or carbene).“Carbones” are still virtually unused in catalysis. Thus, we have decided to study these derivatives, especially in the field of gold catalysis, and to compare them with well-known ligands such as NHCs, phosphines and phosphites. Recently, we were able to synthesize their corresponding GaCl3 complexes and to rationalize their electronic properties through Gutmann’s rules for Lewis acid/Lewis base adducts. In addition, we obtained some ionic “dimers” and we explained their formation on the basis of ligand’s electronic properties. We have shown through these two approaches that carbones are far better donors than NHCs

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裴雍蓮 and Yung-lin Pui. "Syntheses, luminescence studies and host-guest chemistry of d10 and d6metal complexes containing diimine and/or chalcogenolate ligand." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B43894367.

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Pui, Yung-lin. "Syntheses, luminescence studies and host-guest chemistry of d10 and d6 metal complexes containing diimine and/or chalcogenolate ligand." Click to view the E-thesis via HKUTO, 2000. http://sunzi.lib.hku.hk/hkuto/record/B43894367.

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Chao, Yuan-Wei. "Early transition metal complexes with pi donor ligands and their reaction with alkynes." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186222.

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A one step procedure for the preparation of new group 5 amido halides M(NEt₂)ₓCl₅₋ₓ (x = 1, 2, 3), imido halides M(=NAr)Cl₃(L)₂, and group 4 and 5 phenoxide halides. These complexes are obtained easily from the metal halides and trimethylsilyl reagents such as Me₃SiNR₂, Me₃SiNHAr, and Me₃SiOAr. The dimeric amides [M(NEt₂)₂Cl₃]₂ (M = Nb, Ta), the dimeric imide [Ta(=NAr)Cl₃(NH₂Ar)]₂, and the polymeric imide [Ta(=NAr)Cl₃(NH₂Ar)](n) are also prepared in a single step. The use of Me₃SiNR₂ and Me₃SiOAr compounds as amidation and alkoxylation reagents can be extended to prepare the alkoxide amides Ta(NEt₂)(OAr)Cl₃(OEt₂), Ta(NEt₂)(OAr)₂Cl₂(OEt₂), and Ta(OAr)(OAr')Cl₃(OEt₂). When these complexes are reduced using 2 equiv of NaHg in the presence of the appropriate alkyne, the d² alkyne adducts or cycloadducts of the form (alkyne)Ta(NEt₂)(m)X(3-m) (m = 1, 2), (alkyne)Ta(=NAr)X(py)₂, and (R₃CC=CHCH=CCR₃))Ta(=NAr)X(py)₂ (X = OAr, Cl), and (η⁶-C₆Et₆)Ta(OAr)Cl₂, (η⁶-C₆Me₆)Ta(OAr')Cl, (R₃CC=CHCH=CCR₃)Ta(OAr)Cl₂, and (alkyne)Nb(DIPP)₃ are formed. CpTa(NEt₂)₂Cl₂ (Cp = C₅H₅⁻) forms from the reaction of Ta(NEt₂)₂Cl₃(OEt₂) and NaCp. A low yield of [CpTa(NEt₂)₂H₂]₂ is isolated from CpTa(NEt₂)₂Cl₂ and 2 equiv of LiNHAr. The reaction of Ta(NEt₂)₂Cl₃(OEt₂) with various equiv of LiNHAr provides the mono(imido) complex Ta(=NAr)(NEt₂)Cl₂(L)₂, bis(imido) complex Ta(=NAr)₂Cl(py)₂, and tris(imido)complexes [Ta(=NAr)₃(NHAr)]⁻. The analogous complexes of niobium, [Nb(=NAr)(NEt₂)Cl₂(NHEt₂)]₂, Nb(=NAr)₂Cl(py)₂, and [Nb(=NAr)₃(NHAr)]⁻ are prepared from [Nb(NEt₂)₂Cl₃]₂ by a parallel procedure. Preliminary results, not always reproducible, for the syntheses of Li[Ta(=NAr)₃(py)] are also reported. The reaction of MCl₄ (M = Zr, Hf) with 4 equiv of LiNHAr in the presence of donor solvents provides the imido complexes M(=NAr)(NHAr)₂(L)₂.

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Arney, David Sellman Johnson. "Synthesis, structure and reactivity of high-valent early transition metal complexes containing pi coordinated carbocycles and hard pi donor ligands." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185771.

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Ta(DIPP)Cl₄ (1) has been prepared from the reaction of TaCl₅ with 1 equiv of Me₃SiDIPP and is shown to be dimeric. While Ta(DIPP)Cl₄ reacts with Et₂O to form trans-Ta(DIPP)Cl₄(OEt₂) (2), TaCl₅ and Me₃SiDMP react in the presence of Et₂O to provide trans-Ta(DMP)Cl₄(OEt₂) (3) directly. TaCl₅ reacts with 2 equiv of Me₃SiDMP to form the bis phenoxide complex Ta(DMP)₂Cl₃(OEt₂) (6). All of these compounds cyclize 3-hexyne upon their two electron reduction, to form (η⁶-C₆Et₆)Ta(OR)ₓCl₃₋ₓ (OR = DIPP, DMP, x = 1; OR = DMP, x = 2), but do not readily undergo the analogous reaction with 2-butyne. However, (η⁶-C₆Me₆)Ta(DIPP)Cl₂ (10) can be prepared in essentially quantitative yield from the reaction of (η⁶-C₆Me₆)Ta(DIPP)₂Cl (9) with Ta(DIPP)₂Cl₃(OEt₂). The arene ligand in (η⁶-C₆Me₆)Ta(DIPP)Cl₂ (10) is characterized by a folded structure and considerable localization of the π electron density in a 1,4-diene fashion. The thermolysis of (η⁶-C₆Me₆)Ta(DIPP)₂Cl 9 produces free C₆M₆ along with the "tucked in" complex (η¹-C₆Me₅CH₂)Ta(DIPP)₂Cl₂ (11). Compound 11 can be prepared in higher yields from 9 by its thermal decomposition in the presence of Me₃SiCl. Alkylation of tantalum(III) arene complexes affords stable dialkyl (η⁶-C₆Me₆)Ta(DIPP)R₂ and monoalkyl halide species (η⁶-C₆Me₆)Ta(DIPP)RX. The alkyl hydride complexes (η⁶-C₆Me₆)Ta(DIPP)R(H) are also prepared from (η⁶-C₆Me₆)Ta(DIPP)RX and LiBEt₃H. The arene ring in (η⁶-C₆Me₆)Ta(DIPP)Et₂ (18) exhibits a structure consistent with a diene-diyl distortion. The first evidence for the formation of a d¹ arene species is presented in cyclic voltammetry experiments on these compounds. The addition of 4 equiv of LiNHAr to a solution of ZrCl₄(THF)₂ in THF/PY yields Zr(=NAr)(NHAr)₂(PY)₂ (26). Zr(=NAr)(NHAr)(PY)₂ reacts with 1 or 2 equiv of TMSCl in THF/PY to provide Zr(=NAr)(NHAr)Cl(PY)₂ (27) and Zr(=NAr)Cl₂(PY)₃ (28) respectively. MCl₄(THF)₂ (M = Zr or Hf) react with 4 equiv LiNHAr followed by the addition of 2 equiv TMSCl to provide M(=NAr)Cl₂(THF)₂ (24, M = Zr; 25 M = Hf). Both 24 and 25 react with K₂ (C₈H₈) to provide ((η⁸-C₈H₈)M(=NAr))₂ (31, M = Zr; 32, M = Hf). Zr(=NAr)Cl₂(THF)₂ reacts with 1 equiv Li(C₅H₄Me) to provide ((η⁵-C₅H₄Me)Zr(=NAr)Cl)₂ (30). An imprecise structure of this dimeric compound has been determined which exhibits bridging imido functionalities. (η⁵-C₅Me₅)ZrCl₃(THF) reacts with 3 equiv LiNHAr in THF/PY to provide ((η⁵-C₅Me₅)Zr(=NAr)(NHAr)(PY))₂ (33). Compound 33 reacts with 1 equiv TMSCl in THF/PY to provide monomeric (η⁵-C₅Me₅)Zr(=NAr)Cl(PY)₂ (35).

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Rempe, Margaret Eileen. "Electron donor and acceptor properties of trimethylphosphine, triphenylphosphine, and related ligands with transition metals by photoelectron spectroscopy." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186698.

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Gas-phase photoelectron spectroscopy is used to evaluate the a-donation and 1t-acceptance abilities of a series of Group 15 ligands. The free ligands PMe(3-n)Ph(n) (n=0-3), EMe₃ (E=As) and EPh₃ (E=As, Sb, Bi) are examined (Me=CH₃, Ph=C₆H₅) and the trends in lone pair ionizations are discussed. Organometallic compounds investigated include CpMn(CO)2L (L=PPh₃, AsPh₃), Cp'Mn(CO)₂L (L=PPh₃, PMe₃, AsPh₃, SbPh₃), and Mo(CO)₅L (L=PMe₃, PPh₃). Contrary to initial predictions based on electronegativities and solution pKₐ's, the trend in ionization energies for the series PMe(3-n)Ph(n) is PPh₃ < PMePh₂ < PMe₂Ph < PMe₃. The trend in first ionizations is governed by a filled-filled interaction between the lone pair and phenyl rings. The metal ionization energies of organometallic compounds containing PMe₃ and PPh₃ reflect this trend indicating that the above order is also the order of a-donation. These metal ionizations also indicate that all members of the series, PMe(3-n)Ph(n), have the same amount of π-acceptance. Just as in the phenyl containing phosphine ligands, the ligands EPh₃ exhibit filled-filled interactions between the lone pair and phenyl orbitals, but not uniformly. This filled-filled interaction decreases with the heavier elements. The order of lone pair ionizations for EPh₃ is PPh₃ < AsPh₃, SbPh₃, BiPh₃. The destabilization expected upon descent of the periodic table is offset by the effects of decreasing relaxation energy and decreasing filled-filled interactions. Metal ionizations do not strictly follow the trends of the free ligands EPh₃. These metal ionization energies coincide for organometallic compounds where E is phosphorus or arsenic. Metal ionization energies for E=Sb are very slightly stabilized compared to E=P, As. The ligands EPh₃ display the same amount of σ and π interactions in the organometallic compounds examined. It is observed that the identity of R is more important in determining σ/π interactions than the element directly bound to the metal. This work serves to bring together previous literature and current experimental results to understand the structure and bonding in the ligands ER₃ (E=P, As, Sb, Bi and R=Me, Ph).

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Soper, Jake D. "Reactions at nitrogenous ligands on oxidizing group 8 metal centers /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8589.

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Hamdaoui, Mustapha. "Study and applications of the H-Si bond activation of silanes by iridacycles : a contribution to the design of multicompetent catalysts." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF007/document.

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Une nouvelle famille de précatalyseurs à base d'lr(lll) a été découverte. La facilité de leur préparation, leur remarquable stabilité, et surtout leur excellente efficacité catalytique dans plusieurs réactions, c.-à-d. la 0-silylation d'alcools, l'hydrosilylation de fonctions CO et CN et l'activation de la liaison C-F, constituent un ensemble de propriétés que d'autres précatalyseurs organométalliques similaires connus à ce jour ne possèdent pas. Le fait le plus significatif est la mise en évidence expérimentale et théorique que les espèces catalytiques impliquées fonctionnement comme une paire de Lewis du type donneur-accepteur [lr(lll)H]-->[SiR3]. Dans ce cas le ligand silylium doit être considéré comme un ligand Z en appliquant le formalisme de Green, ce qui suggère un état d'oxidation formel de +Ill pour l'atome d'iridium. Cette thèse a contribué à une meilleure compréhension de la chimie du silylium appliquée à la chimie organométallique, et a abouti à l'émergence d'un nouveau champ de recherche qui pourra permettre l'élaboration de nouveaux précatalyseurs multicompétents<br>A new family of highly active iridacyclic lr(lll) precatalysts has been discovered. Notably, these ionic iridacycles are very stable so that their handling under air whether in solution or as solid powder is possible. The relative simplicity of their molecular structures allows their preparation on gram scale through a very simple and convenient synthetic protocol. We identified important iridium-silane intermediates involved in the catalysis of various reactions, e.g. the 0-silylation of alcohols, the hydrosilylation of CO and CN functions, and the activation of the C(sp3)-F bond of fluorocarbons. Experimental and theoretical studies of these intermediates point towards a Lewis donor-acceptor structural formulation of the type [lr(lll)H]-->[SiR3]. These results constitute a significant contribution to the design of future multicompetent precatalysts, and provide an original insight to the bonding within the Si-lr-H motif by considering the silylium ion [SiR3]+ as a Z-type ligand rather than a "traditional" X ligand

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Even, Raymond. "Les premiers semiconducteurs moleculaires : les derives radicalaires des phtalocyanines." Paris 6, 1987. http://www.theses.fr/1987PA066161.

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Synthese de composes pc::(2)lu, pc::(2)ln(ln = yb,tm,dy,nd) a l'etat de grande purete et etude de leurs proprietes electriques intrinseques, ainsi que de celles de pcli, sur monocristaux et sur couches minces; mise en evidence de la possibilite de dopage de pc::(2)lu avec des composes organiques donneurs et accepteurs et avec pcli. Etude de l'absorption optique et observation de bandes de transfert de charge intramoleculaire, confirmee par ailleurs par rpe. Possibilite d'application de couches minces de pclu a la detection de gaz

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Books on the topic "Pi-acceptor and sigma-donor ligands"

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H, Chisholm Malcolm, ed. Early transition metal clusters with [pi]-donor ligands. VCH, 1995.

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Book chapters on the topic "Pi-acceptor and sigma-donor ligands"

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"2.5 Complexes with π-Donor/Acceptor Ligands." In Transition Metals Part 1, edited by Wolfgang A. Herrmann. Georg Thieme Verlag, 1997. http://dx.doi.org/10.1055/b-0035-108418.

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