2000
DOI: 10.1021/ja0019171
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A Combined Experimental and Density Functional Theory Investigation of Hydrocarbon Activation at a Cationic Platinum(II) Diimine Aqua Complex under Mild Conditions in a Hydroxylic Solvent

Abstract: Controlled protonolysis of (N f -N f )Pt(CH 3 ) 2 (1; N f -N f ) ArNdCMesCMedNAr, Ar ) 3,5-(CF 3 ) 2 C 6 H 3 ) with HBF 4 ‚Et 2 O in dichloromethane in the presence of small quantities of water gives the BF 4salt of the aqua complex (N f -N f )Pt(CH 3 )(H 2 O) + (6). When dissolved in trifluoroethanol (TFE), 6(BF 4 -) effects the activation of methane and benzene C-H bonds under very mild conditions. Thus, 6 reacted with benzene in TFE-d 3 at ambient temperature to quantitatively yield (N f -N f )Pt(C 6 H 5 )(… Show more

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Cited by 122 publications
(118 citation statements)
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“…Similar behavior involving protonation at the metal and subsequent hydrocarbon elimination has been reported for (Ar-DAB)PtMe 2 [16][17][18]55] and (Ar-DAB)PtPh 2 [15,32] complexes. The formation of 2a-g is fully consistent with protonation at Pt to give a coordinately unsaturated, five-coordinate Pt IV hydride intermediate that is trapped by acetonitrile, in agreement with mechanistic studies on the mentioned diimine-Pt dimethyl and diphenyl complexes.…”
Section: Synthesis and Characterization Of Metal Complexessupporting
confidence: 77%
“…Similar behavior involving protonation at the metal and subsequent hydrocarbon elimination has been reported for (Ar-DAB)PtMe 2 [16][17][18]55] and (Ar-DAB)PtPh 2 [15,32] complexes. The formation of 2a-g is fully consistent with protonation at Pt to give a coordinately unsaturated, five-coordinate Pt IV hydride intermediate that is trapped by acetonitrile, in agreement with mechanistic studies on the mentioned diimine-Pt dimethyl and diphenyl complexes.…”
Section: Synthesis and Characterization Of Metal Complexessupporting
confidence: 77%
“…One important finding has been that low-temperature protonation of (diimine)Pt(II) dialkyl and Pt(II) diaryl complexes lead to observable, but thermally sensitive, Pt(IV) hydridoalkyl and hydridoaryl complexes that eliminate the respective hydrocarbons upon heating. 60,[76][77][78][79][80][81] Scheme 9 summarizes the mechanistic picture that has emerged for these reactions at (diimine)Pt(II) systems 60,63,74,[82][83][84][85] and at related Pt species with bidentate ligands. Substitution of π-benzene for an aqua (or TFE) ligand occurs as a solvent assisted process for which there is controversy over an associative mechanism.…”
Section: Methodsmentioning
confidence: 99%
“…Such a σ-bond metathesis process appears to nicely explain H/D exchanges between two phenyl groups, via a reasonably looking calculated transition-state structure. 102 (It might be pointed out that the mechanism is not necessarily involved in previously reported, related exchange processes; it appears to us less likely to be involved in exchanges between two methyl groups, 77,111 or between phenyl and methyl groups 60,83 below that for the oxidative cleavage pathway. If these computational results give a true description of the mechanism, then one obvious implication will be that the numerical value that is used for k OC is an upper limit to the real value: The EXSY kinetics represent the energetics for reaching the transition-state for the direct exchange process; the transition state for the oxidative cleavage must necessarily be higher in energy and thence the corresponding rate must be even slower -which strengthens the arguments that led to the conclusion in the previous paragraph: Pt is the kinetically preferred site of protonation.…”
Section: Reductive Coupling and Oxidative Cleavagementioning
confidence: 99%
“…The first step in alkane reductive elimination from many Pt(IV) complexes has been shown to involve dissociation of a labile ligand to generate a 16-electron platinum(IV) intermediate (20,28,40,(57)(58)(59)(60)(61)(62)(63)(64)(65)(66)(67)(68)(69)(70). Isolation of related fivecoordinate Pt(IV) complexes resembling the proposed intermediates discussed in previous sections was reported in 2001 (71,72).…”
Section: Five-coordinate Pt(iv) Intermediatesmentioning
confidence: 86%