DC Field | Value | Language |
---|---|---|
dc.contributor.author | Bailey, Brad C. | ko |
dc.contributor.author | Fan, Hongjun | ko |
dc.contributor.author | Huffman, John C. | ko |
dc.contributor.author | Baik, Mu-Hyun | ko |
dc.contributor.author | Mindiola, Daniel J. | ko |
dc.date.accessioned | 2016-04-12T07:40:25Z | - |
dc.date.available | 2016-04-12T07:40:25Z | - |
dc.date.created | 2015-09-11 | - |
dc.date.created | 2015-09-11 | - |
dc.date.issued | 2007-07 | - |
dc.identifier.citation | JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, v.129, no.28, pp.8781 - 8793 | - |
dc.identifier.issn | 0002-7863 | - |
dc.identifier.uri | http://hdl.handle.net/10203/203333 | - |
dc.description.abstract | The neopentylidene-neopentyl complex (PNP)(TiCHBu)-Bu-t((CH2Bu)-Bu-t) (2;PNP- = N[2-P(CHMe2)(2)-4-methylphenyl](2)), prepared from the precursor (PNP)(TiCHBu)-Bu-t(OTf) (1) and (LiCH2Bu)-Bu-t, extrudes neopentane in neat benzene under mild conditions (25 degrees C) to generate the transient titanium alkylidyne, (PNP)(TiCBu)-Bu-t (A), which subsequently undergoes 1,2-CH bond addition of benzene across the TiC linkage to generate (PNP)(TiCHBu)-Bu-t(C6H5) (3). Kinetic, mechanistic, and theoretical studies suggest the C-H activation process to obey pseudo-first-order in titanium, the alpha-hydrogen abstraction to be the rate-determining step (KIE for 2/2-d(3) conversion to 3/3-d(3) = 3.9(5) at 40 degrees C) with activation parameters Delta H = 24(7) kcal/mol and Delta S = -2(3) cal/mol center dot K, and the post-rate-determining step to be C-H bond activation of benzene (primary KIE = 1.03(7) at 25 degrees C for the intermolecular C-H activation reaction in C6H6 vs C6D6). A KIE of 1.33(3) at 25 degrees C arose when the intramolecular C-H activation reaction was monitored with 1,3,5-C6H3D3. For the activation of aromatic C-H bonds, however, the formation of the sigma-complex becomes rate-determining via a hypothetical intermediate (PNP)(TiCBu)-Bu-t(C6H5), and C-H bond rupture is promoted in a heterolytic fashion by applying standard Lewis acid/base chemistry. Thermolysis of (3) in C6D6 at 95 degrees C over 48 h generates 3-d(6), thereby implying that 3 can slowly equilibrate with A under elevated temperatures with k = 1.2(2) x 10(-5) s(-1), and with activation parameters Delta H = 31(16) kcal/mol and Delta S = 3(9) cal/mol.K. At 95 degrees C for one week, the EIE for the 2-3 reaction in 1,3,5-C6H3D3 was found to be 1.36(7). When 1 is alkylated with LiCH2SiMe3 and KCH2Ph, the complexes (PNP)(TiCHBu)-Bu-t(CH2SiMe3) (4) and (PNP)(TiCHBu)-Bu-t(CH2Ph) (6) are formed, respectively, along with their corresponding tautomers (PNP)TiCHSiMe3((CH2Bu)-Bu-t) (5) and (PNP)TiCHPh((CH2Bu)-Bu-t) (7). By means of similar alkylations of (PNP)TiCHSiMe3(OTf) (8), the degenerate complex (PNP)TiCHSiMe3(CH2SiMe3) (9) or the non-degenerate alkylidene-alkyl complex (PNP)TiCHPh(CH2SiMe3) (11) can also be obtained, the latter of which results from a tautomerization process. Compounds 4/5 and 9, or 6/7 and (11), also activate benzene to afford (PNP)TiCHR(C6H5) (R = SiMe3 (10), Ph (12). Substrates such as FC6H5, 1,2-F2C6H4, and 1,4-F2C6H4 react at the aryl C-H bond with intermediate A, in some cases regioselectively, to form the neopentylidene-aryl derivatives (PNP)(TiCHBu)-Bu-t(aryl). Intermediate A can also perform stepwise alkylidene-alkyl metatheses with 1,3,5-Me<INF>3</INF>C<INF>6</INF>H<INF>3</INF>, SiMe<INF>4</INF>, 1,2-bis(trimethylsilyl)alkyne, and bis(trimethylsilyl)ether to afford the titanium alkylidene-alkyls (PNP)TiCHR(R') (R = 3,5-Me<INF>2</INF>C<INF>6</INF>H<INF>2</INF>, R' = CH<INF>2</INF>-3,5-Me<INF>2</INF>C<INF>6</INF>H<INF>2</INF>; R = SiMe<INF></INF>, R' = CH<INF>2</INF>SiMe<INF>3</INF>; R = SiMe<INF>2</INF>CCSiMe<INF>3</INF>, R' = CH<INF>2</INF>SiMe<INF>2</INF>CCSiMe<INF>3</INF>; R = SiMe<INF>2</INF>OSiMe<INF>3</INF>, R' = CH<INF>2</INF>SiMe<INF>2</INF>OSiMe<INF>3</INF>). | - |
dc.language | English | - |
dc.publisher | AMER CHEMICAL SOC | - |
dc.subject | ALPHA-HYDROGEN ABSTRACTION | - |
dc.subject | ALKYL-ALKENE COMPLEX | - |
dc.subject | CHEMICAL-VAPOR-DEPOSITION | - |
dc.subject | METAL-CARBON BONDS | - |
dc.subject | ALKANE METATHESIS | - |
dc.subject | OXIDATIVE-ADDITION | - |
dc.subject | HYDROCARBON ACTIVATION | - |
dc.subject | N-C | - |
dc.subject | SPECTROSCOPIC CHARACTERIZATION | - |
dc.subject | REVERSIBLE 1,2-RH-ELIMINATION | - |
dc.title | Intermolecular C-H bond activation reactions promoted by transient titanium alkylidynes. Synthesis, reactivity, kinetic, and theoretical studies of the Ti C linkage | - |
dc.type | Article | - |
dc.identifier.wosid | 000247966200032 | - |
dc.identifier.scopusid | 2-s2.0-34548429272 | - |
dc.type.rims | ART | - |
dc.citation.volume | 129 | - |
dc.citation.issue | 28 | - |
dc.citation.beginningpage | 8781 | - |
dc.citation.endingpage | 8793 | - |
dc.citation.publicationname | JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | - |
dc.identifier.doi | 10.1021/ja070989q | - |
dc.contributor.localauthor | Baik, Mu-Hyun | - |
dc.contributor.nonIdAuthor | Bailey, Brad C. | - |
dc.contributor.nonIdAuthor | Fan, Hongjun | - |
dc.contributor.nonIdAuthor | Huffman, John C. | - |
dc.contributor.nonIdAuthor | Mindiola, Daniel J. | - |
dc.type.journalArticle | Review | - |
dc.subject.keywordPlus | ALPHA-HYDROGEN ABSTRACTION | - |
dc.subject.keywordPlus | ALKYL-ALKENE COMPLEX | - |
dc.subject.keywordPlus | CHEMICAL-VAPOR-DEPOSITION | - |
dc.subject.keywordPlus | METAL-CARBON BONDS | - |
dc.subject.keywordPlus | ALKANE METATHESIS | - |
dc.subject.keywordPlus | OXIDATIVE-ADDITION | - |
dc.subject.keywordPlus | HYDROCARBON ACTIVATION | - |
dc.subject.keywordPlus | N-C | - |
dc.subject.keywordPlus | SPECTROSCOPIC CHARACTERIZATION | - |
dc.subject.keywordPlus | REVERSIBLE 1,2-RH-ELIMINATION | - |
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