Low-valent Early Transition Metal Complexes Stabilized by the Chelating Tripod Phosphine Ligand (t-butyl)tris((dimethyl-phosphino)methyl)silane ("trimpsi") PDF Download
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Author: Thomas George Gardner
Publisher:
ISBN:
Category :
Languages : en
Pages : 334
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Book Description
The organometallic chemistry of the early first-row metals has been extended through the use of a new tridentate phosphine ligand, Bu$\sp{\rm t}$Si(CH$\sb2$PMe$\sb2$)$\sb3$, or "trimpsi". The starting materials (trimpsi)TiCl$\sb3$(thf), (trimpsi)VCl$\sb3$(thf), (trimpsi)CrCl$\sb3$, and (trimpsi)ZrCl$\sb4$(dme) have been used to prepare new carbonyl, arene, and alkyl complexes of the early transition metals.
Author: Thomas George Gardner
Publisher:
ISBN:
Category :
Languages : en
Pages : 334
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Book Description
The organometallic chemistry of the early first-row metals has been extended through the use of a new tridentate phosphine ligand, Bu$\sp{\rm t}$Si(CH$\sb2$PMe$\sb2$)$\sb3$, or "trimpsi". The starting materials (trimpsi)TiCl$\sb3$(thf), (trimpsi)VCl$\sb3$(thf), (trimpsi)CrCl$\sb3$, and (trimpsi)ZrCl$\sb4$(dme) have been used to prepare new carbonyl, arene, and alkyl complexes of the early transition metals.
Author: Reto Dorta
Publisher:
ISBN:
Category :
Languages : en
Pages : 123
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Author: Jessica Nicole Boynton
Publisher:
ISBN: 9781321210804
Category :
Languages : en
Pages :
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Book Description
The research in this dissertation is focused on the synthesis, structural, and magnetic characterization of two-coordinate open shell (d1-d4) transition metal complexes. Background information on this field of endeavor is provided in Chapter 1. In Chapter 2 I describe the synthesis and characterization of the mononuclear chromium (II) terphenyl substituted primary amido complexes and a Lewis base adduct. These studies suggest that the two-coordinate chromium complexes have significant spin-orbit coupling effects which lead to moments lower than the spin only value of 4.90 [mu]B owing to the fact that [lambda] (the spin orbit coupling parameter) is positive. The three-coordinated complex 2.3 had a magnetic moment of 3.77 [mu]B. The synthesis and characterization of the first stable two-coordinate vanadium complexes are described in Chapter 3. The values suggest a significant spin orbital angular momentum contribution that leads to a magnetic moment that is lower than their spin only value of 3.87 [mu]B. DFT calculations showed that the major absorptions in their UV-Vis spectra were due to ligand to metal charge transfer transitions. The titanium synthesis and characterization of the bisamido complex along with its three-coordinate titanium(III) precursor are described in Chapter 4. Compound 4.1 was obtained via the stoichiometric reaction of LiN(H)AriPr 6 with the Ti(III) complex TiCl3 *2NMe3 in trimethylamine. The precursor 4.1 has trigonal pyramidal coordination at the titanium atom, with bonding to two amido nitrogens and a chlorine as well as a secondary interaction to a flanking aryl ring of a terphenyl substituent. Compound 4.2 displays a very distorted four-coordinate metal environment in which the titanium atom is bound to two amido nitrogens and to two carbons from a terphenyl aryl ring. This structure is in sharp contrast to the two-coordinate linear structure that was observed in its first row metal (V-Ni) analogs. The synthesis and characterization of mononuclear chromium(II) terphenyl primary substituted thiolate complexes are described in Chapter 5. Reaction of the terphenyl primary thiolate lithium derivatives LiSAriPr4 and LiSArMe6 with CrCl2THF2 in a 2:1 ratio afforded complexes 5.1 and 5.2, which are the very rare examples of chromium(II) thiolates with quasi-two-coordination at the metal center. Both deviate from linearity and have S-Cr-S angles of 111.02(3)° and 107.86(3)° with secondary Cr-C(aryl ring) interactions of ca. 2.115 Å and 1.971 Å respectively. The initial work on titanium and vanadium terphenyl thiolates is described in Appendix I and II. In Chapter 6 I show that the reaction of K2COT (COT= 1,3,5,7-cyclooctatetraene, C8H8) with an aryl chromium(II) halide gave (CrAriPr4)2([mu]2-n3:n4-COT) (6.1) in which a non-planar COT ring is complexed between two CrAriPr4 moieties -- a configuration previously unknown for chromium complexes of COT. OneCr2+ ion is bonded primarily to three COT carbons (Cr--C= 2.22-2.30 Å ) as well as an ipso carbon (Cr-C= ca. 2.47 Å) from a flanking aryl ring of its terphenyl substituent. The other Cr2+ ion bonds to an ipso carbon (Cr-C= ca. 2.53 Å) from its terphenyl substituent as well as four COT carbons (Cr--C= 2.24-2.32 Å). The COT carbon-carbon distances display an alternating pattern, consistent with the non-planarity and non-aromatic character of the ring. The magnetic properties of 6.1 indicate that the Cr2+ ions have a high-spin d4 configuration with S = 2. The temperature dependence of the magnetism indicates that their behavior is due to zero-field splitting of the S = 2 state. Attempts to prepare 6.1 by the direct reaction of quintuple-bonded (CrAriPr4)2 with COT were unsuccessful. (Abstract shortened by UMI.) --Proquest.
Author: Awal Noor
Publisher:
ISBN:
Category :
Languages : en
Pages : 126
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Author: Evan Freiberg
Publisher:
ISBN:
Category :
Languages : en
Pages : 446
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Chapter 1. The chemistry of the metal-metal multiply bonded Tc2(II, II) core has been investigated with bis(diphenylphosphino)methane (dppm). The parent complex, Tc2Cl4(dppm)2, has been prepared from the reaction of Tc2C14(PEt3)4 with dppm. The reactivity of Tc2Cl4(dppm)2 with tert-butyl isocyanide has been studied and a neutral 1:1 adduct, Tc2Cl4(dppm)2CNBut, a cationic 1:2 adduct, [Tc2Cl3(dppm)4(CNBut)2](PF6), and a [mu]-iminyl complex, [Tc2Cl3(dppm)2(CNBut)2CNHBul(PF6), have been prepared. The parent compound and its reaction products have been characterized via a combination of spectroscopic techniques and single crystal X-ray crystallography. The metal-metal bonded ditechnetium bis(dppm) motif is retained in the reaction products. Chapter 2. The reduction of ammonium pertechnetate with bis(diphenylphosphino)methane (dppm), and with diphenyl-2-pyridyl phosphine (Ph2Ppy), has been investigated. The neutral Tc(II) complex, TcCl2(dppm)2, has been isolated from the reaction of (NH4)[TcO4] with excess dppm in refluxing EtOH/HCl. Chemical oxidation with ferricinium hexafluorophosphate results in formation of the cationic Tc(III) analogue, [TcCl2(dppm)2](PF6). The dppm ligands adopt the chelating bonding mode in both complexes, resulting in strained four member metallocycles. With excess PhPpy, the reduction of (NH4)[TcO4] in refluxing EtOH/HCl yields a complex with one chelating Ph2Ppy ligand and one unidentate Ph2Ppy ligand, TcCl3(Ph2Ppy-P, N)(Ph2Ppy-P).
Author: Wayne Allen Chandler
Publisher:
ISBN:
Category : Alkanes
Languages : en
Pages : 300
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Author: D. C. Wood
Publisher:
ISBN:
Category :
Languages : en
Pages :
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