<p>A series of uranium benzyl compounds supported by two hydrotris(3,5-dimethylpyrazolyl) borate (Tp*) ligands has been synthesized and characterized. In addition to the previously reported Tp*₂U(CH₂Ph) (<b>2-Bn</b>), examinations of both steric (<i>tert</i>-butyl, <i>iso</i>-propyl) and electronic (methoxy, picolyl) changes on the aromatic ring led to the formula Tp*₂U(CH₂Ar) (Ar = 4-<i>tert</i>-butylphenyl (<b>2-<i>^t</i>Bu</b>), 4-isopropyl (<b>2-ⁱPr</b>), 2-picolyl (<b>2-pyr</b>), 3-methoxyphenyl (<b>2-OMe</b>). Treatment of the entire series of benzyl compounds with azidotrimethylsilane results in the formation of a neutral, monomeric U(III) compound, Tp*₂U(N₃) (<b>3-N₃</b>), and substituted benzyltrimethylsilane. While there was no observed change in reactivity among the benzyl compounds and Me₃SiN₃, treatment of these compounds with triphenylphosphine oxide saw unique carbon-carbon coupling occur for three of the substituted benzyl compounds. With a single equivalent of OPPh₃, the following products were isolated: Tp*₂U[OP(C₆H₅)(C₆H₅CH₂C₆H₅)] (<b>4-Ph</b>), Tp*₂U[OP(C₆H₅)(C₆H₅-<i>p</i>-<i>i</i>PrC₆H₄)] (<b>4-ⁱPr</b>), Tp*₂U[OP(C₆H₅)(C₆H₅-<i>p</i>-<i>t</i>BuC₆H₄)] (<b>4-<i>^t</i>Bu</b>), Tp*₂U[OP(C₆H₅)(C₆H₅-<i>m</i>-OCH₃C₆H₄)] (<b>4-OMe</b>). </p> <p> A family of uranium(IV) imido complexes of the form Tp*₂U(NR) (R = benzyl (<b>7-Bn</b>), <i>para</i>-tolyl (<b>7-Tol</b>), <i>para</i>-methoxyphenyl (<b>7-OMe</b>), 2,6-diethylphenyl (<b>7-detp</b>), 2,6-diisopropylphenyl (<b>7-dipp</b>)) have been generated by bibenzyl extrusion from <b>2-Bn</b>. When <b>7-Bn</b> and <b>7-Tol</b>, along with previously reported Tp*₂U(N-Ph) (<b>7-Ph</b>) and Tp*₂U(N-Ad) (<b>7-Ad</b>), are treated with isocyanates or isothiocyanates, they readily undergo [2π+2π]-cycloaddition to generate κ²-ureato and κ²-thioureato derivatives, respectively. Use of phenylisoselenocyanate with <b>7-Tol</b> and <b>7-Ph</b> generates a rare κ²-selenoureato complex. Treating <b>7-Tol</b> and <b>7-OMe</b> with benzonitrile or 4-cyanopryidine results in unusual products of multiple bond metathesis, namely κ¹-amidinate U(IV) complexes. </p> <p>A family of dinuclear bis(Tp*) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) uranium compounds with conjugated organic linkers was synthesized to explore possible electronic communication between uranium ions. Trivalent diuranium phenyl alkynyl compounds, Tp*₂UCC(1,3-C₆H₄)CCUTp*₂ (<b>14-<i>meta</i></b>) or Tp*₂UCC(1,4-C₆H₄)CCUTp*₂ (<b>14-<i>para</i></b>), and tetravalent diuranium phenylimido compounds, Tp*₂U(N-1,3-C₆H₄-N)UTp*₂ (<b>15-<i>meta</i></b>) and Tp*₂U(N-1,4-C₆H₄-N)UTp*₂ (<b>15-<i>para</i></b>), were generated from trivalent Tp*₂UCH₂Ph. All compounds were fully characterized both spectroscopically and structurally. The electronic structures of all derivatives were interrogated using magnetic measurements, electrochemistry, and were the subject of computational analyses. All of this data combined established that little electronic communication exists between the uranium centers in these trivalent and tetravalent diuranium molecules.</p> <p>Uranium mono(imido) species have been prepared via oxidation of Cp*U(^MesPDI^Me)(THF) (<b>16-Cp</b>*) and [Cp^PU(^MesPDI^Me)]₂ (<b>16-Cp^P</b>) (Cp* = <i>η</i>⁵-1,2,3,4,5-pentamethylcyclopentadienide; Cp^P = 1-(7,7-dimethylbenzyl)cyclopentadienide; ^MesPDI^Me = 2,6-((Mes)N=CMe)₂C₅H₃N, Mes = 2,4,6-trimethylphenyl) with organoazides. Treating either with N₃DIPP formed uranium(IV) mono(imido) complexes, Cp^PU(NDIPP)(^MesPDI^Me) (<b>17-Cp^P</b>) and Cp*U(NDIPP)(^MesPDI^Me) (<b>17-Cp*</b>), featuring reduced [^MesPDI^Me]^1-. Addition of electron-donating 1-azidoadamantane (N₃Ad) to <b>16-Cp*</b> generated a dimeric product, [Cp*U(NAd)(^MesHPDI^Me)]₂ (<b>18</b>), from radical coupling at the <i>para</i>-pyridine position of the pyridine(diimine) ligand and H-atom abstraction, formed through a monomeric intermediate that was observed in solution but could not be isolated. To support this, Cp*U(<i>^t</i>Bu-^MesPDI^Me)(THF) (<b>16-<i>^t</i>Bu</b>), which has a <i>tert</i>-butyl group protecting the <i>para</i>-position, was also treated with N₃Ad, and the monomeric product, Cp*U(NAd)(<i>^t</i>Bu-^MesPDI^Me) (<b>17-<i>^t</i>Bu</b>), was isolated. All isolated complexes were analyzed spectroscopically and structurally, and dynamic solution behavior was examined using electronic absorption spectroscopy. </p>

Cette thèse porte sur la synthèse et la caractérisation de complexes octaédrique de fer(II) et fer(III) coordinés par un ligand tridente de type scorpionate (symétrie fac) et par trois ligands cyanures. Leur utilisation en tant que metalloligand face à des ions métalliques partiellement bloqués est étudiée. Les ligands cyanures, de par leur caractère ambidente, permettent un accès facile aux espèces hétérobimétalliques. De plus, ces ligands sont connus pour transmettre efficacement l'interaction d'échange magnétique et donc pour favoriser la communication électronique intramoléculaire entre les ions métalliques qu'ils relient. La fonctionalisation des ligands scorpionates permet de contrôler les propriétés électroniques intrinsèques des complexes précurseurs de fer, et donc de moduler les propriétés des espèces polynucléaires obtenues à partir de ces dernières par auto-assemblage. Dans cette thèse, un intérêt particulier est porté aux systèmes {FeCo} en raison de leur capacité à présenter une bistabilité électronique (propriétés photomagnétiques ou de molécules/chaines aimants). Les systèmes cyanuré {FeCo} sont particulièrement adaptés pour l'observation de réarrangements électroniques thermo- et/ou photo-induit, comme en témoignent le nombre important de composés cyanurés photomagnétiques dans la littérature. / The work presented in this PhD dissertation focuses on the synthesis and the characterisation of octahedral iron(II) and iron(III) complexes coordinated by a tridentate ligand of the scorpionate family (fac- geometry) and three cyanide ligands. Their use as metalloligands in respect to partially blocked metal ions is studied. Because of their ambidentate character, cyanide ligands open the door to facile synthesis of heterobimetallic species. Moreover, these ligands are known to be efficient magnetic exchange interaction transmitter, thus favouring intramolecular electronic communication between the metal ions they are bridging. The functionalisation of scorpionate ligands allows control over the intrinsic electronic properties of the iron precursor complexes, thus allows to tune the properties of the obtained polynuclear species from the latter by self-assembly. In this PhD dissertation, a particular interest was taken in {FeCo} systems because of their potential ability to exhibit electronic bistability (photomagnetic properties or SMM/SCM behaviour). Cyanide-bridged {FeCo} systems are particularly suitable for the observation of thermally or light-induced electron rearrangements, as testified by the wide range of photomagnetic cyanide-bridged compounds in the literature.

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