Chemistry of the Tp'W(O) fragment

The research described in this dissertation centers on the chemistry of the tungsten-oxo fragment Tp'W(O) (Tp' = hydridotris(3,5-dimethylpyrazolyl)borate). Starting with the W(IV) complex Tp'W(O)(CO)(I) (1), a variety of W(IV) compounds have been synthesized. Reaction of 1 with LiMe 2Cu affords the methyl complex Tp'W(O)(CO)(CH 3). Treatment of this oxo-methyl complex with HBAr' 4·OEt2 (BAr'4 = tetrakis[3,5--bis(trifluoromethyl)phenyl]borate) generated the cationic hydroxy-carbene complex [Tp'W(O)[=C(OH)Me](N≡CMe)][BAr '4] and the cationic nitrile adduct [Tp' W(O)(N≡CMe)(CO)][BAr'4] in varying ratios depending upon the solvent system.;A series of chiral oxo-alkyne complexes of the type Tp 'W(O)(RC≡CR)(I) have been prepared via addition of Me 3NO to 1 in the presence of an excess of alkyne. Deprotonation of the parent acetylene complex Tp'W(O)(HC≡CH)(I) followed by addition of MeI produced the oxo-propyne complex Tp' W(O)(MeC≡CH) in a 9:1 ration of alkyne rotamers. Addition of n-BuLi to this propyne complex resulted in deprotonation of the terminal acetylene site, and electrophile addition then produced the vinylidene complexes Tp 'W(=C=CMe2)(O)(I) and Tp'W[=C=C(Me)(H)](O)(I) upon addition of MeI or HCl, respectively. Addition of LiMe2CU to the iodide-alkyne compounds Tp'W(O)(RC≡CR)(I) afforded the methyl-alkyne complexes Tp'W(O)(RC≡CR)(Me). Electrophile addition to these methyl-alkyne complexes at the oxo ligand resulted in the alkoxy-alkyne compounds Tp'W(OE)(RC≡CR)(Me) (E = H, Me). Tungsten(VI) oxo-imido complexes have also been synthesized via Me3NO addition to 1 in the presence of an excess of CH3CN or PhCN.;Loss of the carbonyl ligand occurred upon photolysis of Tp' W(O)(CO)(I). In the presence of various trapping ligands (L = CN tBu, N2CHSiMe3, H2C=CH2 and CH3CN), photolysis resulted in products of the type Tp 'W(O)(L)(I). In the case of L = CH3CN, the product is formulated as the side-bound nitrile compound Tp'W(O)(eta 2-N≡CMe)(I). The chiral oxo-ethylene complex Tp' W(O)(H2C=CH2)(I) displays a unique signal for each of the four ethylene protons in the 1H NMR.;Chiral tungsten(IV) aqua-oxo-alkyne complexes [Tp'W(O)(H 2O)(RC≡CR)][OTf] have been synthesized by halide abstraction from the iodide precursors. These cationic aqua complexes undergo deprotonation and isomerization when exposed to Al2O3 to give the dioxo-vinyl W(VI) compounds Tp'W(O)2(CH=CH 2) and Tp'W(O)2(CMe=CHMe). The presumed intermediates, neutral Tp'W(O)(OH)(RC≡CR) compounds, can be accessed by deprotonation of the aqua-alkyne complexes with NaOH.