The Synthesis and Structural Characterization of Main Group and Transition Metal Complexes Supported by Nitrogen Based Ligands

The Synthesis and Structural Characterization of Main Group and Transition Metal Complexes Supported by Nitrogen Based Ligands
Author:
Publisher:
Total Pages:
Release: 2001
Genre:
ISBN:

Download The Synthesis and Structural Characterization of Main Group and Transition Metal Complexes Supported by Nitrogen Based Ligands Book in PDF, Epub and Kindle

Nitrogen based monodentate and bidentate chelating ligands have captured a significant interest due to their ability to coordinate to a wide variety of elements. The â-diketimine, â-ketoiminato, formamidine, pyridineselenolate, and pyrazinecarboxamide ligands have all been employed in this study to further investigate the coordination preferences among main group and transition metals. Steric and electronic properties of these ligands can easily be altered by manipulating the substituents attached, thus leading to predictable structures with potential for many useful and significant applications. Investigations have shown that temperature, solvent, and metal halide employed are all key factors in the reaction outcomes. All of the complexes obtained throughout these studies have been characterized by X-ray crystallography along with other spectroscopic techniques, including NMR, IR, UV/Vis, and M/S. â-diketiminato ligands, [{N(R)C(Me)}2C(H)] where R = Dipp, Mes, commonly referred to as nacnac, have played an important role in the synthesis of novel pnictogenium complexes. Results show that through manipulation of the halide precursor, reaction stoichiometry, and the R substituent on the nacnac both N, N'- and N, C'-metal chelated complexes can be achieved. Additionally, â-ketiminato ligands, [RN(H)(C(Me))2C(Me)=O] where R = Dipp, and [RN(H)C(Me)CHC(Me)=O] where R = C2H4NEt2, have been studied. Both ligands were investigated with a range of d and p block metal halides and alkyls in order to compare and contrast the bulky, flexible, and even multi-dentate nature of each ligand. The preferred metal geometry remains constant for products with either ligand, but the steric protection offered by the individual ligands governs the nuclearity of the products, ranging from tetrameric cages to simple adducts. The formamidinate ligand, [RN(H)C(H)NR] where R = Dipp, was employed in synthesizing several aluminum and zinc complexes. In addition to their numerous applications as cata.

The Synthesis and Structural Characterization of Main Group and Lanthanide Metal Compounds Supported by the Multidentate [N3C] Donor Ligand Tris[(1-isopropylbenzimidazol-2-yl)dimethylsilyl]methyl, [TismPriBenz]M

The Synthesis and Structural Characterization of Main Group and Lanthanide Metal Compounds Supported by the Multidentate [N3C] Donor Ligand Tris[(1-isopropylbenzimidazol-2-yl)dimethylsilyl]methyl, [TismPriBenz]M
Author: David Alexander Vaccaro
Publisher:
Total Pages: 0
Release: 2023
Genre:
ISBN:

Download The Synthesis and Structural Characterization of Main Group and Lanthanide Metal Compounds Supported by the Multidentate [N3C] Donor Ligand Tris[(1-isopropylbenzimidazol-2-yl)dimethylsilyl]methyl, [TismPriBenz]M Book in PDF, Epub and Kindle

Lastly, the ability of the [TismPriBenz]Zn halide series to form ion pair complexes was investigated. [TismPriBenz]ZnI can react with ZnI2 to afford {[TismPriBenz]Zn}2[Zn3I8], which contains the novel zinc halide species [Zn3I8]2−. Additionally, all of the [TismPriBenz]ZnX (X = Cl, Br, I) complexes are able to react with excess ZnX2 in THF to give the series {[TismPriBenz]Zn}[Zn(THF)X3].

Fluoroalkoxy-functionalized Carbenes for Main Group and Transition Metal Complexes

Fluoroalkoxy-functionalized Carbenes for Main Group and Transition Metal Complexes
Author: Jason W. Runyon
Publisher:
Total Pages: 344
Release: 2011
Genre: Electronic dissertations
ISBN:

Download Fluoroalkoxy-functionalized Carbenes for Main Group and Transition Metal Complexes Book in PDF, Epub and Kindle

This dissertation recounts the synthesis and use of imidazol-2-ylidenes for their applications as ligands for main group elements and transition metals and as sterically hindered Lewis bases for hydrogen activation. Chapter 1 reviews the background of carbenes as ligands for main group compounds and transition metal complexes. The history and development of chelating Martin-type fluoroalkoxy ligands to form unique bonding architectures is covered. The synthetic strategies employed to functionalize carbene ligands with fluoroalkoxy substituents is reviewed leading to the development of stable fluoroalkoxy imidazolium zwitterions. A series of new ionic fluoroalkoxy imidazol-2ylidenes is described along with a comparison of the electronic properties to neutral imidazol-2-ylidenes. These fluoroalkoxy imidazol-2-ylidenes were used to prepare chelated hypervalent main group compounds. The structural characterization of the hypervalent adducts is described along with effects due to chelation. Additionally, the characterization of unique fused heterocyclic byproducts formed from unstable main group chelates is reviewed. The synthesis and characterization of transition metal complexes utilizing these ligands are described. Special emphasis is focused on catalytically active transition metals complexes and the influence of the tridentate ligand on catalyst activity. This ligand was also used to allow for the stabilization of iron benzylidene complexes which may have applications towards olefin metathesis. Chapter 2 describes work on hydrogen activation as a project with the U.S. Dept. of Energy's Alabama Chemical Hydrogen Storage Initiative. This project takes advantage of sterically hindered Lewis acid-base pairs to activate small molecules. A wide range of main group element Lewis acids were explored with a variety of mixed results. "Abnormal" coordination of Lewis acids to the carbene backbone results in structures with unique properties and reactivity. These systems were utilized with the goal of reversible heterolytic hydrogen cleavage followed by hydrogen elimination under another set of circumstances.