Download or read book Synthesis Characterization and Density Functional Theory Investigations of Tris cyclopentadienyl Compounds of Zirconium and Hafnium written by Erick Joseph Palmer and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Density functional theory (DFT) calculations were performed to investigate the molecular orbital interactions and the bonding preferences of tris-Cp compounds of zirconium and hafnium. Calculations of the vertical ionization energies of Cp2MCl2 and Cp3MCl (M=Zr, Th) compounds mirror the experimental data observed by PES: Cp2ZrCl2 has a higher first ionization energy than Cp2ThCl2, which is consistent with electronegativity arguments, while Cp3ThCl has a larger first ionization energy than Cp3ZrCl, which is the result of f-orbital stabilization of the 5a2 HOMO in Cp3ThCl. In general, geometry optimizations of a large variety of Cp3MX (M=Zr, Hf; X=halide, H, alkyl, alkoxide, amido) compounds led to the location of two primary structures along the potential energy surface: a 3-5 structure, which exhibits three h5-C5H5 ligands, and a 2-5,1-1 structure, which exhibits two h5-C5H5 and one h1-C5H5 ligands. The binding preference of these structure types have been shown to be dependent upon the p-donor ability of the X ligands. When X has no p-donor ability as in the case of the hydride compounds, the 3-5 structure is more stable for both zirconium and hafnium. When X is a strong p-donor, the 2-5,1-1 structure is more stable for both zirconium and hafnium. When X is a weak p-donor as in the halide compounds, the zirconium complexes prefer the 3-5 geometry while the hafnium complexes prefer the 2-5,1-1 geometry. These structural preferences indicate a competition between the p-donation of the X lone pair and the tris-Cp ligand set. This competition leads to a destabilization of the 15e molecular orbital when X is a strong p-donor; this destabilization causes the 2-5,1-1 structure to be more stable than the 3-5 structure. (MeCp)3HfCl and (MeCp)4Zr were synthesized and fully characterized. Their crystal structures are discussed in light of our theoretical model presented. Solid state dynamics in these systems were also studied via variable-temperature CP-MAS NMR.

Download or read book Synthesis Characterization and Reactivity of Ylidyne and Ylido Complexes Supported by Scorpionato Ligands written by Priyabrata Ghana and published by Springer. This book was released on 2018-12-11 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the development of the first open-shell heavier tetrylidyne complexes featuring a tetrel-centered unpaired electron, and unprecedented metallatetrylidynes containing a multiply-bonded, linear-coordinated single heavier tetrel atom embedded between two metal centers. The chemistry of compounds featuring triple bonds of the heavier Group-14 elements Si–Pb with transition metals is a very challenging research area, which combines modern molecular main-group element with transition-metal chemistry, and is of fundamental importance for the understanding of chemical bonding. During the last 15 years, the research in this area has witnessed considerable progress in isolating a series of closed-shell tetrylidyne complexes. However, despite numerous attempts, open-shell tetrylidyne complexes and heavier group 14 element congeners of metallacarbynes and carbide complexes remained inaccessible. In this book, readers will find more about the synthesis, full characterization and reactivity studies of these novel complexes that uncovered a plethora of exceptional products, including a novel m3-silicido complex, the first dimetallasilacumulene with a linear, two-coordinated single silicon atom and the first compounds of planar tetracoordinated silicon (ptSi) (Anti-van’t Hoff-Le Bell Silicon). Readers will also learn about the isolation and full characterization of the first room-temperature stable disilavinylidene, a silicon analogue of the very reactive vinylidenes (R2C=C:), and the first intermetallic plumbylidyne ligand transfer reactions.

Download or read book The Synthesis and Characterization of Organometallic Polysulfanes and Polyselenanes of Titanium IV Zirconium IV and Hafnium IV written by James M. McCall and published by . This book was released on 1983 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The complexes Cp(,2)M(SH)(,2), where M = Ti and Zr, have been prepared and treated with S(,8) and >N-S(,x)-NN = benzimidazolyl, phthalimidyl and x = 1, 2, to give the metallacyclohexasulfanes Cp(,2)MS(,5). Reaction of Cp(,2)TI(SH)(,2) with >N-SR, where >N = phthalimidyl, succinimidyl, gave the complexes Cp(,2)Ti(S(,2)R)(,2) (R = CHMe(,2)) and Cp(,2)Ti(SR)(S(,3)R) (R = Ph, 4-C(,6)H(,4)Me). The thiolates Cp(,2)Ti(Cl)SR and Cp(,2)Ti(SR)(,2) (R = CHMe(,2), CMe(,3), Ph, 4-C(,6)H(,4)Me) were prepared for comparison. Treatment of the complexes Cp(,2)MCl(,2) with anhydrous solutions of Li(,2)E(,x) gave the complexes Cp(,2)ME(,5), where M = Ti, Zr, Hf and E = S, Se. The compounds (RCp)(,2)TiS(,5) (R = Me, SiMe(,3)),CH(,2)Cp(,2)TiS(,5), and (Me(,5)Cp)CpTiS(,5) were prepared similarly. Reaction of Li(,2)S(,x) with (Me(,5)Cp)(,2)MCl(,2) gave the metallacyclotetrasulfanes (Me(,5)Cp)(,2)MS(,3). The complex Cp(,2)Ti{S(CH(,2))(,3)S} was synthesized. Variable temperature ('1)H NMR studies established the barriers ((DELTA)G('(NOT=))) for ME(,x) and TiS(,2)C(,3) ring reversal in the above complexes. The crystal structures of Cp(,2)Ti(SPh)(S(,3)Ph), Cp(,2)MS(,5), and (Me(,5)Cp)(,2)TiS(,3) are discussed." --