Barriers to rotation about carbon-phosphorus bonds in tert-butylphosphines.  Phosphorus-31-proton spin-spin coupling as a probe of molecular geometry

Bushweller, C. Hackett; Brunelle, Jacques A.

doi:10.1021/ja00799a021

Cited by 27 publications

(6 citation statements)

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“…Line shape analyses were performed to calculate the exchange rates and in turn the barrier to rotation about the carbon−phosphorus bond. The activation parameters, Δ H ⧧ = 8.7(3) kcal mol -1 , and Δ S ⧧ = −7(2) cal mol -1 K -1 , are in good agreement with those observed previously for hindered rotation about the P−C bond in tri- tert -butylphosphine, Δ H ⧧ = 9.0(4) kcal mol -1 and Δ S ⧧ = 2(4) cal mol -1 K -1 …”

Section: Resultssupporting

confidence: 89%

“…As the temperature is raised the resonances broaden, merge, and appear as a single resonance at 0 °C. These observations are similar to those observed for hindered rotation of the tert -butyl group about the P−C bond in tri- tert -butylphosphine. , Accordingly, it is proposed that these spectral changes are due to a similar hindered rotation about the P−C bond in the tri- tert -butylphosphine ligand in complex 3 . This process is unrelated to the dynamical interconverion of the two isomers of the cluster.…”

Section: Resultssupporting

confidence: 82%

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Remarkable Dynamical Opening and Closing of Platinum and Palladium Pentaruthenium Carbido Carbonyl Cluster Complexes

Adams

Captain

et al. 2003

Inorg. Chem.

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The reaction of Ru(5)(CO)(15)(mu(5)-C), 1, with Pt(PBu(t)(3))(2) at room temperature yielded the mixed-metal cluster complex PtRu(5)(CO)(15)(PBu(t)(3))(C), 2, in 52% yield. Compound 2 consists of a mixture of two interconverting isomers in solution. One isomer, 2A, can be isolated by crystallization from benzene/octane solvent. The second isomer, 2B, can be isolated by crystallization from diethyl ether. Both were characterized crystallographically. Isomer 2A consists of a square pyramidal cluster of five ruthenium atoms with a phosphine-substituted platinum atom spanning the square base. Isomer 2B consists of a square pyramidal cluster of five ruthenium atoms with a phosphine-substituted platinum atom on an edge on the square base. The two isomers interconvert rapidly on the NMR time scale at 40 degrees C, deltaG(313)++ = 11.4(8) kcal mol(-1), deltaH++ = 8.8(5) kcal mol(-1), deltaS++ = -8.4(9) cal mol(-1) K(-1). The reaction of Pd(PBu(t)(3))(2) with compound 1 yielded two new cluster complexes: PdRu(5)(CO)(15)(PBu(t)(3))(mu(6)-C), 3, in 50% yield and Pd(2)Ru(5)(CO)(15)(PBu(t)(3))(2)(mu(6)-C), 4, in 6% yield. The yield of 4 was increased to 47% when an excess of Pd(PBu(t)(3))(2) was used. In the solid state compound 3 is structurally analogous to 2A, but in solution it also exists as a mixture of interconverting isomers; deltaG(298)++ = 10.6(6) kcal mol(-1), deltaH++ = 9.7(3) kcal mol(-1), and deltaS++ = -3(1) cal mol(-1) K(-1) for 3. Compound 4 contains an octahedral cluster consisting of one palladium atom and five ruthenium atoms with an interstitial carbido ligand in the center of the octahedron, but it also has one additional Pd(PBu(t)(3)) grouping that is capping a triangular face of the ruthenium cluster. The Pd(PBu(t)(3)) groups in 4 also undergo dynamical interchange that is rapid on the NMR time scale at 25 degrees C; deltaG(298)++ = 11(1) kcal mol(-1), deltaH++ = 10.2(4) kcal mol(-1), and deltaS++ = -3(2) cal mol(-1) K(-1) for 4.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 82%

Remarkable Dynamical Opening and Closing of Platinum and Palladium Pentaruthenium Carbido Carbonyl Cluster Complexes

Adams

Captain

et al. 2003

Inorg. Chem.

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“…From a more pragmatic viewpoint the present NMR data corroborate the various procedures used to separate 13C contact and pseudocontact shifts where the assumption is made that 'H shifts are purely of dipolar nature. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] This assumption should be checked through studies using several lanthanides, as contact contributions are not always negligible for protons. 18 The Gd3+ induced shifts, recently reported for the first time by Ajisaka and Kainosho,6 afford in principle a new method of separation of the two forms of shifts; however, this ion leads to enormous line broadening for DP A complexes as well as for various LSR adducts and shifts are difficult or impossible to measure.…”

mentioning

confidence: 99%

Carbon-13 nuclear magnetic resonance of organophosphorus compounds. X. Ring-size variation in heterocyclic phosphines, phosphonium salts, and phosphine oxides

Gray¹,

Cremer²,

Marsi³

1976

J. Am. Chem. Soc.

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“…The spectral changes are due to a dynamical exchange process involving hindered rotation about the P−C bond, which renders the methyl groups inequivalent at low temperatures. This phenomenon is well documented in related systems that contain PBu t groupings …”

Section: Resultsmentioning

confidence: 57%

Activation of Hydrogen and Related Small Molecules by the Unsaturated Cluster Complex PtOs₃(CO)₇(PBu^t₃)(μ-PBu^t₂)(μ₄-CHCMeCH)

et al. 2008

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Reactions of the unsaturated mixed metal cluster complex PtOs 3 (CO) 7 (PBu t 3 )(µ-PBu t 2 )(µ 4 -CHCMeCH), 1, with hydrogen, HGePh 3 , and PhC 2 H have been investigated. Compound 1 reacts reversibly with hydrogen at room temperature to yield the dihydrido complex PtOs 3 (CO) 7 (PBu t 3 )(µ-PBu t 2 )(µ 4 -CHC-MeCH)(µ-H)(H), 2. A computational analysis shows that the hydrogen addition occurs by oxidative addition at the electronically unsaturated platinum atom and passes through two unstable intermediates before giving the final product 2. Compound 1 reacts with HGePh 3 at the Ge-H bond to form the complex PtOs 3 (CO) 7 (PBu t 3 )(µ-PBu t 2 )(µ 4 -CHCMeCH)(GePh 3 )(µ-H), 3, but in this reaction the HGePh 3 addition occurred at one of the osmium atoms and a CO ligand was shifted to the platinum atom. Compound 1 reacts with PhC 2 H by loss of the platinum atom and the PBu t 3 ligand to give the compound Os 3 (CO) 7 (µ-PBu t2 )[µ 3 -η 5 -CHCMeC(H)CCPhH], 4. In the process, the PhC 2 H molecule became bonded to the CHCMeCH ligand in 1 and its hydrogen atom was shifted to the phenyl-substituted carbon atom to form a triply bridging CHCMeC(H)CCPhH ligand. All of the products were characterized by single-crystal X-ray diffraction analyses.

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Barriers to rotation about carbon-phosphorus bonds in tert-butylphosphines. Phosphorus-31-proton spin-spin coupling as a probe of molecular geometry

Cited by 27 publications

References 1 publication

Remarkable Dynamical Opening and Closing of Platinum and Palladium Pentaruthenium Carbido Carbonyl Cluster Complexes

Remarkable Dynamical Opening and Closing of Platinum and Palladium Pentaruthenium Carbido Carbonyl Cluster Complexes

Carbon-13 nuclear magnetic resonance of organophosphorus compounds. X. Ring-size variation in heterocyclic phosphines, phosphonium salts, and phosphine oxides

Activation of Hydrogen and Related Small Molecules by the Unsaturated Cluster Complex PtOs₃(CO)₇(PBu^t₃)(μ-PBu^t₂)(μ₄-CHCMeCH)

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Barriers to rotation about carbon-phosphorus bonds in tert-butylphosphines. Phosphorus-31-proton spin-spin coupling as a probe of molecular geometry

Cited by 27 publications

References 1 publication

Remarkable Dynamical Opening and Closing of Platinum and Palladium Pentaruthenium Carbido Carbonyl Cluster Complexes

Remarkable Dynamical Opening and Closing of Platinum and Palladium Pentaruthenium Carbido Carbonyl Cluster Complexes

Carbon-13 nuclear magnetic resonance of organophosphorus compounds. X. Ring-size variation in heterocyclic phosphines, phosphonium salts, and phosphine oxides

Activation of Hydrogen and Related Small Molecules by the Unsaturated Cluster Complex PtOs3(CO)7(PBut3)(μ-PBut2)(μ4-CHCMeCH)

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Activation of Hydrogen and Related Small Molecules by the Unsaturated Cluster Complex PtOs₃(CO)₇(PBu^t₃)(μ-PBu^t₂)(μ₄-CHCMeCH)