Computational Studies of Doped Germanium Nanoclusters.

1. INTRODUCTION.................................................................................................1 2. THEORETICAL BACKGROUND.....................................................................9 2.1 ELECTRON LOCALIZATION FUNCTION........................................................9 2.2 MOLECULAR MECHANISM OF HYDROGEN RELEASE REACTIONS. ............13 2.3 REFERENCES ............................................................................................20 3. ELECTRONIC STRUCTURE OF GERMANIUM MONOHYDRIDES GenH, n = 1-3........................................................................................................23 3.1 INTRODUCTION................................................................................................25 3.2 COMPUTATIONAL DETAILS ..............................................................................26 3.3 RESULTS AND DISCUSSION...............................................................................27 3.3.1 GeH, GeH+ and GeH−..............................................................................27 3.3.2 Ge2H, Ge2H+ and Ge2H−..........................................................................31 3.3.3 Ge3H, Ge3H+ and Ge3H−..........................................................................39 3.3.4 Electronic Structure and Bonding ...........................................................42 3.4 CONCLUSIONS .................................................................................................49 3.5 REFERENCES....................................................................................................51 4. CHROMIUM-DOPED GERMANIUM CLUSTERS CrGen (n = 2 - 3): GEOMETRY, ELECTRONIC STRUCTURE AND TOPOLOGY OF CHEMICAL BONDING.....................................................................................55 4.1 INTRODUCTION................................................................................................57 4.2 COMPUTATIONAL DETAILS..............................................................................58 4.3 RESULTS AND DISCUSSION ..............................................................................60 4.3.1. CrGe2 and CrGe2 +...................................................................................60 4.3.2. CrGe3 and CrGe3 +...................................................................................62 4.3.3. Topology of the Chemical Bonds in CrGe2 and CrGe3 ..........................64 4.4 CONCLUSIONS .................................................................................................71 4.5 REFERENCES....................................................................................................72 5. INTERACTION OF DIATOMIC GERMANIUM WITH LITHIUM ATOMS: ELECTRONIC STRUCTURE AND STABILITY..........................75 5.1 INTRODUCTION................................................................................................77 5.2 COMPUTATIONAL DETAILS..............................................................................78 5.3 RESULTS AND DISCUSSION ..............................................................................80 5.3.1 Ge2 and its anions....................................................................................80 5.3.2 Ge2Li .......................................................................................................84 5.3.3 Ge2Li2 and Ge2Li3 ...................................................................................89 5.3.4 Nature of Ge-Li bond ..............................................................................95 5.4 CONCLUSIONS ...............................................................................................104 5.5 REFERENCES..................................................................................................106 6. INTERACTION OF TRIATOMIC GERMANIUM WITH LITHIUM ATOMS: ELECTRONIC STRUCTURE AND STABILITY OF Ge3Lin CLUSTERS (n = 0 – 3)...................................................................................... 109 6.1 INTRODUCTION.............................................................................................. 111 6.2 COMPUTATIONAL DETAILS ........................................................................... 112 6.3 RESULTS AND DISCUSSION............................................................................ 113 6.3.1 Ge3 and its anions.................................................................................. 113 6.3.2 Ge3Li..................................................................................................... 118 6.3.3 Ge3Li2 and Ge3Li3 ................................................................................. 123 6.3.4 Nature of the Ge-Li bond...................................................................... 128 6.4 CONCLUSIONS ............................................................................................... 137 6.5 REFERENCES ................................................................................................. 139 7. LITHIUM DOPED GERMANIUM NANOWIRE........................................ 141 7.1 INTRODUCTION.............................................................................................. 143 7.2 EXPERIMENTAL OVERVIEW........................................................................... 144 7.3 COMPUTATIONAL DETAILS ............................................................................ 145 7.4 RESULTS AND DISCUSSION............................................................................ 146 7.4.1 Experimental Results ............................................................................ 146 7.4.2 Computational Results .......................................................................... 150 7.4.2.1 Ge4Lim (m = 1 – 3).......................................................................................150 7.4.2.2 Ge5Lim (m = 1 – 3).......................................................................................155 7.4.2.3 Ge9Li5, Ge18Li6, Ge27Li11 and Ge36Li16 .......................................................160 7.5 CONCLUSIONS ............................................................................................... 165 7.6 REFERENCES ................................................................................................. 168 APPENDIX ........................................................................................................... 171 THE BORON BUCKYBALL.............................................................................. 171 SUMMARY AND OUTLOOK............................................................................ 181 SAMENVATTING EN VOORUITBLIK........................................................... 187 LIST OF PUBLICATIONS ................................................................................. 193 Used in this thesis .......................................................................................... 193 Other .............................................................................................................. 194status: publishe

Jahn–Teller Distortion in Polyoligomeric Silsesquioxane (POSS) Cations

We investigated the symmetry breaking mechanism in cubic octa-<i>tert</i>-butyl silsesquioxane and octachloro silsesquioxane monocations (Si₈O₁₂(C­(CH₃)₃)₈⁺ and Si₈O₁₂Cl₈⁺) using density functional theory (DFT) and group theory. Under <i>O</i>_<i>h</i> symmetry, these ions possess ²T_2g and ²E_g electronic states and undergo different symmetry breaking mechanisms. The ground states of Si₈O₁₂(C­(CH₃)₃)₈⁺ and Si₈O₁₂Cl₈⁺ belong to the <i>C</i>_3<i>v</i> and <i>D</i>_4<i>h</i> point groups and are characterized by Jahn–Teller stabilization energies of 3959 and 1328 cm^–1, respectively, at the B3LYP/def2-SVP level of theory. The symmetry distortion mechanism in Si₈O₁₂Cl₈⁺ is Jahn–Teller type, whereas in Si₈O₁₂(C­(CH₃)₃)₈⁺ the distortion is a combination of both Jahn–Teller and pseudo-Jahn–Teller effects. The distortion force acting in Si₈O₁₂(C­(CH₃)₃)₈⁺ is mainly localized on one Si–(<i>tert</i>-butyl) group, while in Si₈O₁₂Cl₈⁺ it is distributed over the oxygen atoms. The main distortion forces acting on the Si₈O₁₂ core arise from the coupling between the electronic state and the vibrational modes, identified as 9t_2g + 1e_g + 3a_2u for the Si₈O₁₂(C­(CH₃)₃)₈⁺ and 1e_g + 2e_g for Si₈O₁₂Cl₈⁺

Extraction and coordination behavior of diphenyl hydrogen phosphine oxide towards actinides

<p>Extraction behavior of some selected actinides like U(VI), Th(IV), and Am(III) was investigated with three different H-phosphine oxides, <i>viz.</i> diphenyl hydrogen phosphine oxide (DPhPO), dihexyl hydrogen phosphine oxide (DHePO) and diphenyl phosphite (DPP). The H-phosphine oxides exhibited a dual nature towards the extraction of actinides where the ligand not only extracts the metals by cation exchange but also by coordination with the phosphoryl group at lower and higher acidic concentrations, respectively. Among all ligands employed, DPhPO showed highest extraction with actinides with a substituent dependent trend as follows: DPhPO > DHePO > DPP. This trend emphasizes the importance of substituents around the phosphine oxide towards their extraction of actinides. The coordination behavior of DPhPO was studied by investigating its corresponding complexes with Th(NO₃)₄ and UO₂(NO₃)₂. The metal complexes of these actinides were characterized using FT-IR, ¹H and ³¹P NMR spectroscopic techniques. Density Functional Theory (DFT) calculations were also performed to understand the electronic and geometric structure of the ligand and the corresponding metal complexes.</p

One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone

Readily available phosphoramidites incorporating TADDOL-related diols with an acyclic backbone turned out to be excellent ligands for asymmetric gold catalysis, allowing a number of mechanistically different transformations to be performed with good to outstanding enantioselectivities. This includes [2 + 2] and [4 + 2] cycloadditions of ene-allenes, cycloisomerizations of enynes, hydroarylation reactions with formation of indolines, as well as intramolecular hydroaminations and hydroalkoxylations of allenes. Their preparative relevance is underscored by an application to an efficient synthesis of the antidepressive drug candidate (−)-GSK 1360707. The distinctive design element of the new ligands is their acyclic dimethyl ether backbone in lieu of the (isopropylidene) acetal moiety characteristic for traditional TADDOL’s. Crystallographic data in combination with computational studies allow the efficiency of the gold complexes endowed with such one-point binding ligands to be rationalized

One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone

Readily available phosphoramidites incorporating TADDOL-related diols with an acyclic backbone turned out to be excellent ligands for asymmetric gold catalysis, allowing a number of mechanistically different transformations to be performed with good to outstanding enantioselectivities. This includes [2 + 2] and [4 + 2] cycloadditions of ene-allenes, cycloisomerizations of enynes, hydroarylation reactions with formation of indolines, as well as intramolecular hydroaminations and hydroalkoxylations of allenes. Their preparative relevance is underscored by an application to an efficient synthesis of the antidepressive drug candidate (−)-GSK 1360707. The distinctive design element of the new ligands is their acyclic dimethyl ether backbone in lieu of the (isopropylidene) acetal moiety characteristic for traditional TADDOL’s. Crystallographic data in combination with computational studies allow the efficiency of the gold complexes endowed with such one-point binding ligands to be rationalized

One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone

Readily available phosphoramidites incorporating TADDOL-related diols with an acyclic backbone turned out to be excellent ligands for asymmetric gold catalysis, allowing a number of mechanistically different transformations to be performed with good to outstanding enantioselectivities. This includes [2 + 2] and [4 + 2] cycloadditions of ene-allenes, cycloisomerizations of enynes, hydroarylation reactions with formation of indolines, as well as intramolecular hydroaminations and hydroalkoxylations of allenes. Their preparative relevance is underscored by an application to an efficient synthesis of the antidepressive drug candidate (−)-GSK 1360707. The distinctive design element of the new ligands is their acyclic dimethyl ether backbone in lieu of the (isopropylidene) acetal moiety characteristic for traditional TADDOL’s. Crystallographic data in combination with computational studies allow the efficiency of the gold complexes endowed with such one-point binding ligands to be rationalized

One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone

Readily available phosphoramidites incorporating TADDOL-related diols with an acyclic backbone turned out to be excellent ligands for asymmetric gold catalysis, allowing a number of mechanistically different transformations to be performed with good to outstanding enantioselectivities. This includes [2 + 2] and [4 + 2] cycloadditions of ene-allenes, cycloisomerizations of enynes, hydroarylation reactions with formation of indolines, as well as intramolecular hydroaminations and hydroalkoxylations of allenes. Their preparative relevance is underscored by an application to an efficient synthesis of the antidepressive drug candidate (−)-GSK 1360707. The distinctive design element of the new ligands is their acyclic dimethyl ether backbone in lieu of the (isopropylidene) acetal moiety characteristic for traditional TADDOL’s. Crystallographic data in combination with computational studies allow the efficiency of the gold complexes endowed with such one-point binding ligands to be rationalized

One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone

Readily available phosphoramidites incorporating TADDOL-related diols with an acyclic backbone turned out to be excellent ligands for asymmetric gold catalysis, allowing a number of mechanistically different transformations to be performed with good to outstanding enantioselectivities. This includes [2 + 2] and [4 + 2] cycloadditions of ene-allenes, cycloisomerizations of enynes, hydroarylation reactions with formation of indolines, as well as intramolecular hydroaminations and hydroalkoxylations of allenes. Their preparative relevance is underscored by an application to an efficient synthesis of the antidepressive drug candidate (−)-GSK 1360707. The distinctive design element of the new ligands is their acyclic dimethyl ether backbone in lieu of the (isopropylidene) acetal moiety characteristic for traditional TADDOL’s. Crystallographic data in combination with computational studies allow the efficiency of the gold complexes endowed with such one-point binding ligands to be rationalized