Download or read book Synthesis of Electrophilic Rhodium and Iridium Complexes and Investigation of Reactivity for C-H Bond Activation and Functionalization written by Kate E. Allen and published by . This book was released on 2013 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct methods for the transformation of alkanes into alcohols, alkenes, amines and other functionalized products would have a great impact on industrial processes. In this thesis the work described is aimed at developing electrophilic Rh and Ir systems to promote C-H bond activation and functionalization of alkanes and arenes. Several approaches have been taken to prepare the target complex [Tp*Ir(OH2)3]+ (Tp* = hydridotris(3,5-dimethylpyrazoyl)borate). While this species has not been synthesized, C-N coupling between ethylene and N-iodosuccinimide has been observed during the course of this study and is promoted by Tp*Ir(C2H4)2. Electrophilic Rh and Ir complexes bearing dimethylbutadiene (DMB) ligands have been found to be poor species for C-H activation due to low stability at elevated temperatures. Interestingly, formation of the unique five-coordinate [(DMB)Ir(COE)Cl]2 dimer has been observed. Alkane dehydrogenation using ([superscript dm]Phebox)Ir(OAc)2(OH2) ([superscript dm]Phebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) is promoted at 200 °C and results in quantitative formation of olefin and (([superscript dm]Phebox)Ir(OAc)H. At early reaction times 1-octene is the major product, supporting terminal C-H activation by the Ir center. Oxygen can be utilized in this system as a hydrogen acceptor to promote regeneration of the Ir bisacetate species at room temperature. This is the first example of regeneration of a complex for dehydrogenation using oxygen. Unfortunately, the system is not catalytic as the reaction with oxygen is not compatible with the high temperatures required for C-H bond activation. In order to expand the number of examples of alkane dehydrogenation at Ir[superscript III] centers, a second system utilizing the [superscript tBu]NOCON ([superscript tBu]NOCON = 4,6-di-tert-butyl-(1,3-bis(2-pyridyloxy)benzene)) pincer ligand has been developed. Complexes ([superscript tBu] NOCON)M(OAc)2OH2 (M = Rh or Ir) were synthesized and explored for C-H bond functionalization. The Ir analogue promotes alkane dehydrogenation at 200 °C, but is not stable under the reaction conditions. Arene functionalization has also been explored using Ir-aryl complexes. The product of benzene C-H activation, (Phebox)Ir(OAc)Ph has been investigated for arene functionalization using hypervalent iodide reagents and CO. Reactions utilizing C6F5I(TFA)2 are promising and may potentially yield functionalized arene. Coordination of CO to the Ir center has been observed and isomerization of the trans product, ([superscript dm]Phebox)Ir(CO)(OAc)Ph, occurs at room temperature to yield the cis isomer ([superscript dm] Phebox)Ir(OAc)(CO)Ph.