Using insertion chemistry to synthesize new coordination environments for organoactinide complexes to examine structure, bonding, and reactivity .

摘要

This dissertation uses insertion chemistry to create new coordination environments for actinide complexes and examines their subsequent reactivity. Since actinides play such a prominent role in nuclear processes and their disposal is an environmental issue, the study of their structure, reactivity, and coordination chemistry is of interest. This work has resulted in the isolation of new organoactinide complexes, new reactivity patterns, and new coordination modes of common substrates not seen before in f element chemistry.;Chapter 1 gives details about the synthesis of mono(pentamethycyclopentadienyl) divalent lanthanide complexes, (C5Me5)Ln(BPh4), and their unusual structural arrangements that were observed in their crystal structures. The reductive and displacement reactivity of the samarium and ytterbium complexes is also described.;In Chapter 2, the utility of cationic complexes in making sterically crowded uranium complexes is described with the synthesis of (C5Me 5)2(C5Me4H)UMe. This complex does not have reductive reactivity like (C5Me5)3UMe and not all the methyl groups are displaced from the cyclopentadienyl ring plane equally. The synthesis of (C5Me5)2UMe[CH(SiMe 3)2], the first mixed-alkyl actinide metallocene complex, is also shown.;Chapter 3 starts a series of chapters on the metallocene amidinate moiety, {(C5Me5)2[iPrNC(Me)N iPr]}3- from insertion of iPrN=C=N iPr into one methyl group of (C5Me5)2AnMe 2 to produce, (C5Me5)2[iPrNC(Me)N iPr]AnMe, An = Th, U. In addition, insertion of AdN3, Ad = adamantyl, into (C5Me5)2AnMe2 produces the metallocene triazenido complex, (C5Me5) 2[(Ad)NNN(Me)]AnMe.;Cationic metallocene amidinate complexes can be made by the abstraction of the methyl group in (C5Me5)2[i PrNC(Me)NiPr]AnMe with BPh3 to produce {(C 5Me5)2[iPrNC(Me)NiPr]An}{BPh 3Me}, An = Th, U. Reaction of KC5Me5 with each actinide complex produces the thorium "tuck-in" complex, (C 5Me5)(C5Me4CH2)[ iPrNC(Me)NiPr]Th, by C-H bond activation, and the trivalent uranium complex, (C5Me5)2[iPrNC(Me)N iPr]U, by reduction. This is detailed in Chapter 4.;The comparative reactivity of (C5Me5)2[ iPrNC(Me)NiPr]UMe and (C5Me5) 2[(Ad)NNN(Me)]UMe is described in chapter 5. The abstraction of the methyl group by silver and copper salts to produce the corresponding halide and triflate complexes is demonstrated. This is the first time that copper salts have been shown to have this type of reactivity. Interestingly, the reaction of the amidinate complex with LiCH2SiMe3 leads to the trivalent species, (C5Me5)2[ iPrNC(Me)NiPr]U, through reduction, but the reaction with the triazenido complex with yields the corresponding alkyl complex, (C 5Me5)2[(Ad)NNN(Me)]U(CH2SiMe3 ). Further, the reaction of (C5Me5)2[ iPrNC(Me)NiPr]UMe with the bulky alcohol, HOC 6H2 iPr2-2,6-4-Me, produces an unusual outer sphere aryloxide complex, {(C5Me5) 2[iPrNC(Me)NiPr]U}{OAr}.;In chapter 6, the reductive chemistry of (C5Me5) 2[iPrNC(Me)NiPr]U is examined. Aryl sulfides, copper salts, and TlC5H5 prove to react with the trivalent complex, but this complex is far much less reactive than other trivalent uranium complexes.;In chapter 7, the synthesis of a rare trivalent thorium complex, (C 5Me5)2[iPrNC(Me)NiPr]Th is reported. In addition, the electronic structure and bonding of trivalent metallocene amidinate complexes, (C5Me5)2[ iPrNC(Me)NiPr]An, An = Th, Pa, U, Np, Pu, Am, is described.;Chapter 8 looks at the insertion chemistry of (C5Me5 )2U(C≡CPh)2 with the unsaturated substrates, CO2, PhNCO, Me3CC≡N, and Me3CN≡C. Insertion chemistry is one of the steps in the mechanism of catalytic and cascade reactions with the dialkynyl complex.;Appendix A describes a new way of abstracting a methyl group of (C 5Me5)2ThMe2 with 2,6-tetramethylpiperdine oxide (TEMPO) to produce, (C5Me5)2[C 5H6NMe4-2,6-O]ThMe. The methyl group can also be abstracted with CuBr to produce the corresponding bromide. In addition, the reaction of (C5Me5)2Eu with benzaldehyde azine, PhCH=NN=CHPh, is described. The dark purple product, (C5Me 5)2Eu(C14H12N2), is still a divalent europium with a coordinating ligand. Moreover, the lanthanide metallocene amidinate complex, (C5Me5)2[iPrNC(Me)N iPr]Ce, was crystallographically characterized and is discussed.