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Carbon-hydrogen bond activation and ...

Kanzelberger, Mira T.

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Carbon-hydrogen bond activation and related chemistry of "PCP-pincer"-ligated iridium.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Carbon-hydrogen bond activation and related chemistry of "PCP-pincer"-ligated iridium./
Author:	Kanzelberger, Mira T.
Description:	149 p.
Notes:	Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2930.
Contained By:	Dissertation Abstracts International65-06B.
Subject:	Chemistry, Inorganic. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3134848
ISBN:	0496820737

Carbon-hydrogen bond activation and related chemistry of "PCP-pincer"-ligated iridium.
Kanzelberger, Mira T.

Carbon-hydrogen bond activation and related chemistry of "PCP-pincer"-ligated iridium. - 149 p.

Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2930.

Thesis (Ph.D.)--Rutgers The State University of New Jersey - New Brunswick, 2004.

Reaction of (PCP)Ir (PCP = kappa3-2,6-( tBu2PCH2)2C6H 3) with arenes gives the C-H bond activation products, (PCP)Ir(aryl)(H), 1. These complexes serve as a model system for the higher-energy alkyl hydride analogs, (PCP)Ir(alkyl)(H), which are presumed intermediates in a catalytic alkane dehydrogenation cycle. The aryl hydrides undergo rapid intermolecular arene exchange at room temperature. The dynamics of benzene exchange in (PCP)Ir(phenyl)(H), 1-phenyl, have been studied in detail by low temperature 1H and 31P NMR spectroscopy. The rate of benzene exchange in mesitylene- d12 at low temperature is independent of the concentration of free benzene from 0.008--3.5 M, indicative of a dissociative mechanism. Rates of exchange were obtained by computer simulation of the spectra from -35°C to 2.9°C. From the Eyring relationship, DeltaH&Dagger; = 11.2 +/- 0.7 kcal/mol and DeltaS&Dagger; = -7.6 +/- 1.2 e.u. were obtained for benzene dissociation from 1-phenyl. An average KIE of kH/kD = 1.6 was found, and a solvent isotope effect of 1.02 +/- 0.03, also supportive of a dissociative mechanism with negligible participation of solvent. Addition of CO to 1 gives the corresponding 6-coordinate CO adducts which are kinetically very stable and do not undergo arene exchange at room temperature.

ISBN: 0496820737Subjects--Topical Terms:

517253
Chemistry, Inorganic.

Carbon-hydrogen bond activation and related chemistry of "PCP-pincer"-ligated iridium.
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100 1 $a Kanzelberger, Mira T. $3 1939254
245 1 0 $a Carbon-hydrogen bond activation and related chemistry of "PCP-pincer"-ligated iridium.
300 $a 149 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2930.
500 $a Director: Alan S. Goldman.
502 $a Thesis (Ph.D.)--Rutgers The State University of New Jersey - New Brunswick, 2004.
520 $a Reaction of (PCP)Ir (PCP = kappa3-2,6-( tBu2PCH2)2C6H 3) with arenes gives the C-H bond activation products, (PCP)Ir(aryl)(H), 1. These complexes serve as a model system for the higher-energy alkyl hydride analogs, (PCP)Ir(alkyl)(H), which are presumed intermediates in a catalytic alkane dehydrogenation cycle. The aryl hydrides undergo rapid intermolecular arene exchange at room temperature. The dynamics of benzene exchange in (PCP)Ir(phenyl)(H), 1-phenyl, have been studied in detail by low temperature 1H and 31P NMR spectroscopy. The rate of benzene exchange in mesitylene- d12 at low temperature is independent of the concentration of free benzene from 0.008--3.5 M, indicative of a dissociative mechanism. Rates of exchange were obtained by computer simulation of the spectra from -35°C to 2.9°C. From the Eyring relationship, DeltaH&Dagger; = 11.2 +/- 0.7 kcal/mol and DeltaS&Dagger; = -7.6 +/- 1.2 e.u. were obtained for benzene dissociation from 1-phenyl. An average KIE of kH/kD = 1.6 was found, and a solvent isotope effect of 1.02 +/- 0.03, also supportive of a dissociative mechanism with negligible participation of solvent. Addition of CO to 1 gives the corresponding 6-coordinate CO adducts which are kinetically very stable and do not undergo arene exchange at room temperature.
520 $a In order to study (PCP)Ir(alkyl)(H) more directly, fast-timescale photolysis studies were proposed, and the synthesis of suitable precursors was undertaken. Addition of methyl iodide to the 4-coordinate complex, (PCP)Ir(CO), did not yield the expected 6-coordinate oxidative addition product, (PCP)Ir(methyl)(I)(CO), but an unprecedented, stable, 5-coordinate acetyliridium complex via oxidative addition/migratory insertion. Reaction of aldehydes with (PCP)Ir yielded diastereomeric (PCP)Ir(alkyl)(H)(CO) complexes via oxidative addition/retro migratory insertion.
520 $a Reactions of (PCP)Ir with other small molecules were also explored. Under excess N2, the mononuclear dinitrogen complex, (PCP)Ir(N2 ) was formed in quantitative yield. In the absence of N2, partial conversion to the previously reported dinuclear dinitrogen complex, (PCP)Ir(N2)Ir(PCP), was observed. Reaction of (PCP)Ir with aniline yielded the 5-coordinate N-H activation product, (PCP)Ir(NHC6H 5)(H), while for alkyl amines, coordination via the nitrogen lone pair seemed to be preferred.
590 $a School code: 0190.
650 4 $a Chemistry, Inorganic. $3 517253
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710 2 0 $a Rutgers The State University of New Jersey - New Brunswick. $3 1017590
773 0 $t Dissertation Abstracts International $g 65-06B.
790 1 0 $a Goldman, Alan S., $e advisor
790 $a 0190
791 $a Ph.D.
792 $a 2004
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3134848