The crystal structure of methyl[hydrotris(pyrazol-1-yl)borato]carbonylplatinum(II)

Oliver, J. D.; Rush, Peder E.

doi:10.1016/s0022-328x(00)91597-3

Cited by 20 publications

(7 citation statements)

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“…9,24 The IR spectrum of TpPtMe(CO) displays an absorption for the CO stretch at 2088 cm -1 , 30 cm -1 higher than in the Tp′ analogue, which is consistent with stronger donor character for Tp′ versus Tp. The solid-state structure of TpPtMe(CO) is square planar with a bidentate Tp ligand, 25 but the complex is fluxional at room temperature in CDCl 3 , and at low temperature a trigonal-bipyramidal structure has been inferred from NMR data: two of the three pyrazole rings are magnetically equivalent, and all three show platinum coupling. 9,24b In contrast, the solid-state IR data indicates κ 3 coordination of the Tp′ ligand in Tp′PtMe(CO) (13), while the solution IR spectrum (hexanes) of 13 shows two absorptions for the B-H stretch (2521, 2478 cm -1 ) as well as two CO absorptions (2081, 2065 cm -1 ) (Figure 9).…”

Section: Resultsmentioning

confidence: 99%

“…Comparison with TpPtMe(CO) is appropriate. , The IR spectrum of TpPtMe(CO) displays an absorption for the CO stretch at 2088 cm -1 , 30 cm -1 higher than in the Tp‘ analogue, which is consistent with stronger donor character for Tp‘ versus Tp. The solid-state structure of TpPtMe(CO) is square planar with a bidentate Tp ligand, but the complex is fluxional at room temperature in CDCl 3 , and at low temperature a trigonal-bipyramidal structure has been inferred from NMR data: two of the three pyrazole rings are magnetically equivalent, and all three show platinum coupling. ,24b …”

Section: Resultsmentioning

confidence: 99%

“…4 Hz,Tp′CH),5.84 (s,2H,4 JPt-H ) 8.2 Hz, Tp′CH), 2.37, 2. 25,2.18 (s,3H,9H,6H,Tp′CH3), 0.87 (s, 3H, 2 JPt-H ) 72.2 Hz, Pt-CH3). 13…”

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Acid-Assisted Reductive Elimination as a Route to Platinum(II) Products from Platinum(IV) Tris(pyrazolyl)borate Reagents

et al. 2000

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A series of chiral cationic platinum(II) complexes of the type [κ 2 -((Hpz*)BHpz* 2 )Pt(R)(L)]-[BAr′ 4 ] (R ) Me, L ) MeCN (3), t BuNC (4), py (5), CO (6), CH 2 dCH 2 (7), PMe 2 Ph (8); R ) Ph, L ) MeCN (10); pz* ) 3,5-dimethylpyrazolyl, BAr′ 4 ) tetrakis(3,5-trifluoromethylphenyl)borate) has been prepared. Protonation of Tp′PtMe 2 H (1) or Tp′PtPh 2 H (2) (Tp′ ) hydridotris-(3,5-dimethylpyrazolyl)borate) occurs selectively at a pyrazole nitrogen atom and induces reductive elimination of methane or benzene. Subsequent addition of ligand, L, traps the platinum(II) intermediate and yields 3-8 and 10. Addition of 2 equiv of PMe 2 Ph led to the formation of trans-[κ 1 -((Hpz*)BHpz* 2 )Pt(Me)(PMe 2 Ph) 2 ][BAr′ 4 ] ( 9), a square-planar complex containing a rare monodentate protonated tris(pyrazolyl)borate ligand. Deprotonation of the pyrazolium ring (present after protonation of 1 or 2 and trapping with added ligand) led to the synthesis of neutral platinum(II) complexes of the type Tp′PtR(L) (R ) Me, L ) MeCN (11), SMe 2 (12), CO (13), CH 2 dCH 2 (14); R ) Ph, L ) MeCN ( 15)). Complexes 11, 12, and 15 exhibit square-planar coordination with a bidentate Tp′ ligand, while complex 14 is trigonal bipyramidal. Tp′PtMe(CO) ( 13) is present in solution in both isomeric forms. X-ray structure determinations for the cationic complexes 3 and 6-9 and the neutral squareplanar complex 12 are reported.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Acid-Assisted Reductive Elimination as a Route to Platinum(II) Products from Platinum(IV) Tris(pyrazolyl)borate Reagents

et al. 2000

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“…Either structure could be the ground state of the intermediate, as calculations on such σ-complexes indicate that they lie in a shallow energy surface and rapid conversion between these different structures is expected. , The κ 2 -Tp Me 2 configuration shown for intermediate A (or A ‘) is consistent with the square-planar coordination geometry generally preferred for a Pt(II) center. A number of neutral Pt(II) complexes with an ancillary tris(pyrazolyl)borate ligand have been isolated, and available crystal structures of such species illustrate this bidentate coordination mode of the Tp ligand. , …”

Section: Discussionmentioning

confidence: 99%

“…A number of neutral Pt(II) complexes with an ancillary tris(pyrazolyl)borate ligand have been isolated, and available crystal structures of such species illustrate this bidentate coordination mode of the Tp ligand. 30,37 The structure of the σ-methane complex is reminiscent of a closely related Pt(II) benzene adduct, [κ 2 -(HTp Me 2)Pt II H(η 2 -C 6 H 6 )] + , which has been crystallographically characterized. 38a In this cationic complex, one pyrazolyl ring is protonated and a pseudo-square-planar environment around the platinum is obtained.…”

Section: Discussionmentioning

confidence: 99%

Reductive Elimination/Oxidative Addition of Carbon−Hydrogen Bonds at Pt(IV)/Pt(II) Centers: Mechanistic Studies of the Solution Thermolyses of Tp^Me_²Pt(CH₃)₂H

et al. 2003

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Reductive elimination of methane occurs upon solution thermolysis of kappa(3)-Tp(Me)2Pt(IV)(CH(3))(2)H (1, Tp(Me)2 = hydridotris(3,5-dimethylpyrazolyl)borate). The platinum product of this reaction is determined by the solvent. C-D bond activation occurs after methane elimination in benzene-d(6), to yield kappa(3)-Tp(Me)2Pt(IV)(CH(3))(C(6)D(5))D (2-d(6)), which undergoes a second reductive elimination/oxidative addition reaction to yield isotopically labeled methane and kappa(3)-Tp(Me)2Pt(IV)(C(6)D(5))(2)D (3-d(11)). In contrast, kappa(2)-Tp(Me)2Pt(II)(CH(3))(NCCD(3)) (4) was obtained in the presence of acetonitrile-d(3), after elimination of methane from 1. Reductive elimination of methane from these Pt(IV) complexes follows first-order kinetics, and the observed reaction rates are nearly independent of solvent. Virtually identical activation parameters (DeltaH(++)(obs) = 35.0 +/- 1.1 kcal/mol, DeltaS(++)(obs) = 13 +/- 3 eu) were measured for the reductive elimination of methane from 1 in both benzene-d(6) and toluene-d(8). A lower energy process (DeltaH(++)(scr) = 26 +/- 1 kcal/mol, DeltaS(++)(scr) = 1 +/- 4 eu) scrambles hydrogen atoms of 1 between the methyl and hydride positions, as confirmed by monitoring the equilibration of kappa(3)-Tp(Me)()2Pt(IV)(CH(3))(2)D (1-d(1)()) with its scrambled isotopomer, kappa(3)-Tp(Me)2Pt(IV)(CH(3))(CH(2)D)H (1-d(1'). The sigma-methane complex kappa(2)-Tp(Me)2Pt(II)(CH(3))(CH(4)) is proposed as a common intermediate in both the scrambling and reductive elimination processes. Kinetic results are consistent with rate-determining dissociative loss of methane from this intermediate to produce the coordinatively unsaturated intermediate [Tp(Me)2Pt(II)(CH(3))], which reacts rapidly with solvent. The difference in activation enthalpies for the H/D scrambling and C-H reductive elimination provides a lower limit for the binding enthalpy of methane to [Tp(Me)2Pt(II)(CH(3))] of 9 +/- 2 kcal/mol.

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The Coordination Chemistry of Pyrazole‐Derived Ligands

Trofimenko¹

1986

Progress in Inorganic Chemistry

660

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The crystal structure of methyl[hydrotris(pyrazol-1-yl)borato]carbonylplatinum(II)

Cited by 20 publications

References 33 publications

Acid-Assisted Reductive Elimination as a Route to Platinum(II) Products from Platinum(IV) Tris(pyrazolyl)borate Reagents

Acid-Assisted Reductive Elimination as a Route to Platinum(II) Products from Platinum(IV) Tris(pyrazolyl)borate Reagents

Reductive Elimination/Oxidative Addition of Carbon−Hydrogen Bonds at Pt(IV)/Pt(II) Centers: Mechanistic Studies of the Solution Thermolyses of Tp^Me_²Pt(CH₃)₂H

The Coordination Chemistry of Pyrazole‐Derived Ligands

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The crystal structure of methyl[hydrotris(pyrazol-1-yl)borato]carbonylplatinum(II)

Cited by 20 publications

References 33 publications

Acid-Assisted Reductive Elimination as a Route to Platinum(II) Products from Platinum(IV) Tris(pyrazolyl)borate Reagents

Acid-Assisted Reductive Elimination as a Route to Platinum(II) Products from Platinum(IV) Tris(pyrazolyl)borate Reagents

Reductive Elimination/Oxidative Addition of Carbon−Hydrogen Bonds at Pt(IV)/Pt(II) Centers: Mechanistic Studies of the Solution Thermolyses of TpMe2Pt(CH3)2H

The Coordination Chemistry of Pyrazole‐Derived Ligands

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Reductive Elimination/Oxidative Addition of Carbon−Hydrogen Bonds at Pt(IV)/Pt(II) Centers: Mechanistic Studies of the Solution Thermolyses of Tp^Me_²Pt(CH₃)₂H