Synthesis and reactivity of mixed metallocene cyclopentadienyl cyclooctatetraenyl uranium complexes

This dissertation describes the investigation of the organometallic chemistry of uranium complexes with ligand environments alternative to the ubiquitous [(C5Me5)2]2- ligand set found in so many organometallic complexes. Specifically, the effect on uranium chemistry of replacing one (C5Me5)1- ligand with (C8H8)2- was probed. The resulting [(C 5Me5)(C8H8)]3- ligand set has been used as a platform to synthesize [(C5Me5)( 8H8)U]1+ complexes and investigate their unusual reactivity.;Chapter 1 describes the reductive reactivity of [(C5Me 5)(C8H8)U]2(mu -C8H8) with PhEEPh (E = S, Se, and Te), phenazine, and nitrobenzene. The results in this chapter constitute the only examples of the (C8H8)2- ligand being used for ligand-based reduction.;Chapter 2 describes the synthesis of [(eta 5-C5Me5)(eta8-C 8H8)U(mu-OTf)]2 (OTf = OSO 2CF3) by taking advantage of the ligand-based reduction described in Chapter 1. [(eta5-C5Me 5)(eta8-C8H8)U( mu-OTf)]2 is a convenient precursor for generating [(C 5Me5)(C8H8)U]1+ alkyl and aryl complexes including the first stable uranium metallocene phenyl complex.;Chapter 3 describes the synthesis of highly reactive, sterically unsaturated uranium monoalkyl complexes (C5Me5)(C8H 8)UR that decompose in solution to form a unique tuck-in uranium complex (eta8-C8H8)(eta5:eta 1-C5Me4CH2)U. The reactivity of this tuck-in complex is examined with substrates known to insert into U-C bonds including iPrN=C=NiPr, tBuN≡C, and C≡O.;Chapter 4 describes studies related to the reaction of (C5Me 5) 3U with C8H8 to form [(C5Me 5)(C8H8)U]2(mu-C 8H8). This is the only example of multiple SIR reactions occurring from a single molecule. This Chapter describes the formation of a series of bis(cyclopentadienyl) cyclooctatetraenyl dianion uranium complexes which support the formation of [(C5Me5)(C8H 8)U]2(mu-C8H8) through a "(C5Me5)2(C8H8)U" intermediate via sterically induced reduction (SIR).;Chapter 5 describes the examination of the uranium bipyridine complexes [(eta5-C5Me5)( eta8-C8H8)U(bipy- kappa2N,N') (bipy = 2,2'-bipyridine) and [(eta5-C5Me5)( eta8-C8H8)U(Me2bipy- kappa2N,N') (Me2bipy = 4,4'-dimethyl-2,2'-bipyridine) to determine if they contain neutral bipyridine bound to a U3+ or bipyridyl radical anion bound to a U4+ metal center. X-ray crystallography, infrared spectroscopy, and density functional theory calculations were employed to determine the oxidation state of uranium.