Author : David Shaffer
Publisher :
ISBN 13 : 9781267646378
Total Pages : 233 pages
Book Rating : 4.6/5 (463 download)
Book Synopsis The Effects of Ligand Electronics on the Properties and Reactivity of Late Transition Metal Complexes by : David Shaffer
Download or read book The Effects of Ligand Electronics on the Properties and Reactivity of Late Transition Metal Complexes written by David Shaffer and published by . This book was released on 2012 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overarching theme of the work herein is the investigation of the effects of ligand electronics on the electronic structure and reactivity of non-innocent late transition metal complexes. Chapter 2 describes the electronic structure of (nacnacR[supercript]) Rh II[superscript] (phdisq) (nacnacR[superscript] = CH[C(R)(N-i [superscript] Pr2 C6 H3)]2, -[superscript], R = CH3, CF3; phdisq = 9,10-phenanthrenediiminosemiquinone *[superscript]-[superscript]), which incorporates both a reducible diimine ligand and a reducing [beta]-diketiminate ligand. The complex is assigned as having highly delocalized, closed shell frontier orbitals. One-electron oxidation of (nacnacCH3[superscript]) RhII[superscript] (phdisq) produces a delocalized ligand-based radical, while one-electron reduction gives (nacnac CH3[superscript]) RhII[superscript]) (phda). Chapter 3 studies the oxidative addition of halogen substrates to (nacnacR[superscript]) Rh(phdisq). Chlorine and bromine are observed to add in a normal trans fashion, but the addition of iodine is found to be dependent on the electronic properties of the ligands, forming either an [eta]1 -I2 complex or the oxidative addition product. Chapter 4 reports the reactions of (nacnacCH3[superscript])Rh(phdisq) with haloacids. The addition of HCl quickly produces the product [(nacnacH[superscript]CH3[superscript] RhCl2 (phdaH2)]+[superscript] (phdaH2 = 9,10-phenanthrenediamine), which is the result of protonation of the (nacnacCH3[superscript]) ligand, oxidative addition to the rhodium center, and hydrogenation of the phdi ligand. This reaction is reversible, and the deprotonated (nacnacCH3[superscript])RhCl2 (phdaH2) is also isolable but undergoes slow disproportionation. All phdaH2 complexes are dehydrogenated by oxygen to give the corresponding phdi products. Chapter 5 examines the differences between (nacnacCH3[superscript])Co(phdisq) and (nacnacCH3[superscript])Rh(phdisq). The solid state structures are completely analogous, suggesting analogous electronic ground states. Differences in the solution spectroscopic characterization between the rhodium and cobalt complexes suggest the existence of a thermally accessible triplet state for (nacnacCH3[superscript])Co(phdisq). Chapter 6 addresses the question of how the introduction of a reducible ligand will affect the electrocatalytic potential of a catalyst for proton reduction. The complexes (adi)M(bdt) (M = Ni, Co; adi = N-N'-bis(2,4,6-trimethylphenyl)-acenapthene-1,2-diimine, bdt = 1,2-benzenedithiolate2-[superscript] are described, and the cobalt complex is evaluated as an electrocatalyst for H+[superscript] reduction. Results indicate that the [eta]-acidic nature of the adi ligand makes the cobalt center less basic, thus reducing its catalytic efficiency. Chapter 7 compares tungsten complexes of the well-known redox active bis(3,5-di- tert- butyl-phenolate)amido3-[superscript] ligand (ONO3-[superscript]) and the novel bis(4-methyl-thiophenolate)amido3-[superscript] (SNS3-[superscript]) ligand. While W(ONO)2 is found to be an `innocent' tungsten(VI) complex, W(SNS)2 is described as tungsten(IV) with partially oxidized (SNS) ligands. W(SNS)2 has a highly distorted geometry that is ascribed to [eta]-[eta] interactions in the solid state.
