Thermodynamic studies of [HPt(EtXantphos) 2] + and [(H) 2Pt(EtXantphos) 2] 2 +

Alex Miedaner, James W. Raebiger, Calvin J. Curtis, Susie M. Miller, Daniel L DuBois

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Abstract

[HPt(EtXantphos) 2](PF 6) (where EtXantphos is 9,9-dimethyl-4,5-bis(diethylphosphino)xanthene) can be prepared by the reduction of Pt(COD)Cl 2 (where COD is 1,4-cyclooctadiene) with hydrazine in the presence of 2 equiv of the diphosphine ligand followed by exchange of Cl - with PF 6 -. Deprotonation of [HPt(EtXantphos) 2](PF 6) (pK a = 27.3 in acetonitrile) leads to the formation of Pt(EtXantphos) 2, which has been characterized by an X-ray diffraction study. Pt(EtXantphos) 2 has a distorted tetrahedral geometry. The average chelate bite angle is 108.2°, and the dihedral angle between the two planes formed by the phophorus atoms of each diphophine ligand and platinum is 80.4°. Protonation of [HPt(EtXantphos) 2] - results in the formation of [(H) 2Pt(EtXantphos 2] 2+, which has a pK a of 6.8 in acetonitrile. Oxidation of Pt(EtXantphos) 2 with ferrocenium tetrafluoroborate produces [Pt(EtXantphos) 2] 2+. Pt(EtXantphos 2] 2- undergoes two reversible one-electron reductions (E 1/2/II/I) = -0.81 V versus ferrocene and E 1/2(I/0) = ∼0.97 V), and HPt(EtXantphos 2] - undergoes a reversible one-electron oxidation E 1/2(II/III) = -0.23 V). These half-wave potentials and the pK a values of [HPt(EtXantphos 2] - and [(H) 2Pt(EtXantphos 2] 2- have been used to calculate five additional homolytic and heterolytic bond-dissociation free energies for these two hydride species and for [HPt(EtXantphos 2] 2- The extensive thermodynamic characterization of this hydride system provides useful insights into the factors controlling the reactivity of these complexes.

Original languageEnglish
Pages (from-to)2670-2679
Number of pages10
JournalOrganometallics
Volume23
Issue number11
DOIs
Publication statusPublished - May 24 2004

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hydrazine
crack opening displacement
Hydrides
hydrides
acetonitrile
Xanthenes
Thermodynamics
Ligands
Oxidation
thermodynamics
Deprotonation
ligands
oxidation
Electrons
Protonation
hydrazines
Dihedral angle
Platinum
chelates
Free energy

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

Cite this

Thermodynamic studies of [HPt(EtXantphos) 2] + and [(H) 2Pt(EtXantphos) 2] 2 + . / Miedaner, Alex; Raebiger, James W.; Curtis, Calvin J.; Miller, Susie M.; DuBois, Daniel L.

In: Organometallics, Vol. 23, No. 11, 24.05.2004, p. 2670-2679.

Research output: Contribution to journalArticle

Miedaner, A, Raebiger, JW, Curtis, CJ, Miller, SM & DuBois, DL 2004, 'Thermodynamic studies of [HPt(EtXantphos) 2] + and [(H) 2Pt(EtXantphos) 2] 2 + ', Organometallics, vol. 23, no. 11, pp. 2670-2679. https://doi.org/10.1021/om034238i
Miedaner, Alex ; Raebiger, James W. ; Curtis, Calvin J. ; Miller, Susie M. ; DuBois, Daniel L. / Thermodynamic studies of [HPt(EtXantphos) 2] + and [(H) 2Pt(EtXantphos) 2] 2 + . In: Organometallics. 2004 ; Vol. 23, No. 11. pp. 2670-2679.
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abstract = "[HPt(EtXantphos) 2](PF 6) (where EtXantphos is 9,9-dimethyl-4,5-bis(diethylphosphino)xanthene) can be prepared by the reduction of Pt(COD)Cl 2 (where COD is 1,4-cyclooctadiene) with hydrazine in the presence of 2 equiv of the diphosphine ligand followed by exchange of Cl - with PF 6 -. Deprotonation of [HPt(EtXantphos) 2](PF 6) (pK a = 27.3 in acetonitrile) leads to the formation of Pt(EtXantphos) 2, which has been characterized by an X-ray diffraction study. Pt(EtXantphos) 2 has a distorted tetrahedral geometry. The average chelate bite angle is 108.2°, and the dihedral angle between the two planes formed by the phophorus atoms of each diphophine ligand and platinum is 80.4°. Protonation of [HPt(EtXantphos) 2] - results in the formation of [(H) 2Pt(EtXantphos 2] 2+, which has a pK a of 6.8 in acetonitrile. Oxidation of Pt(EtXantphos) 2 with ferrocenium tetrafluoroborate produces [Pt(EtXantphos) 2] 2+. Pt(EtXantphos 2] 2- undergoes two reversible one-electron reductions (E 1/2/II/I) = -0.81 V versus ferrocene and E 1/2(I/0) = ∼0.97 V), and HPt(EtXantphos 2] - undergoes a reversible one-electron oxidation E 1/2(II/III) = -0.23 V). These half-wave potentials and the pK a values of [HPt(EtXantphos 2] - and [(H) 2Pt(EtXantphos 2] 2- have been used to calculate five additional homolytic and heterolytic bond-dissociation free energies for these two hydride species and for [HPt(EtXantphos 2] 2- The extensive thermodynamic characterization of this hydride system provides useful insights into the factors controlling the reactivity of these complexes.",
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N2 - [HPt(EtXantphos) 2](PF 6) (where EtXantphos is 9,9-dimethyl-4,5-bis(diethylphosphino)xanthene) can be prepared by the reduction of Pt(COD)Cl 2 (where COD is 1,4-cyclooctadiene) with hydrazine in the presence of 2 equiv of the diphosphine ligand followed by exchange of Cl - with PF 6 -. Deprotonation of [HPt(EtXantphos) 2](PF 6) (pK a = 27.3 in acetonitrile) leads to the formation of Pt(EtXantphos) 2, which has been characterized by an X-ray diffraction study. Pt(EtXantphos) 2 has a distorted tetrahedral geometry. The average chelate bite angle is 108.2°, and the dihedral angle between the two planes formed by the phophorus atoms of each diphophine ligand and platinum is 80.4°. Protonation of [HPt(EtXantphos) 2] - results in the formation of [(H) 2Pt(EtXantphos 2] 2+, which has a pK a of 6.8 in acetonitrile. Oxidation of Pt(EtXantphos) 2 with ferrocenium tetrafluoroborate produces [Pt(EtXantphos) 2] 2+. Pt(EtXantphos 2] 2- undergoes two reversible one-electron reductions (E 1/2/II/I) = -0.81 V versus ferrocene and E 1/2(I/0) = ∼0.97 V), and HPt(EtXantphos 2] - undergoes a reversible one-electron oxidation E 1/2(II/III) = -0.23 V). These half-wave potentials and the pK a values of [HPt(EtXantphos 2] - and [(H) 2Pt(EtXantphos 2] 2- have been used to calculate five additional homolytic and heterolytic bond-dissociation free energies for these two hydride species and for [HPt(EtXantphos 2] 2- The extensive thermodynamic characterization of this hydride system provides useful insights into the factors controlling the reactivity of these complexes.

AB - [HPt(EtXantphos) 2](PF 6) (where EtXantphos is 9,9-dimethyl-4,5-bis(diethylphosphino)xanthene) can be prepared by the reduction of Pt(COD)Cl 2 (where COD is 1,4-cyclooctadiene) with hydrazine in the presence of 2 equiv of the diphosphine ligand followed by exchange of Cl - with PF 6 -. Deprotonation of [HPt(EtXantphos) 2](PF 6) (pK a = 27.3 in acetonitrile) leads to the formation of Pt(EtXantphos) 2, which has been characterized by an X-ray diffraction study. Pt(EtXantphos) 2 has a distorted tetrahedral geometry. The average chelate bite angle is 108.2°, and the dihedral angle between the two planes formed by the phophorus atoms of each diphophine ligand and platinum is 80.4°. Protonation of [HPt(EtXantphos) 2] - results in the formation of [(H) 2Pt(EtXantphos 2] 2+, which has a pK a of 6.8 in acetonitrile. Oxidation of Pt(EtXantphos) 2 with ferrocenium tetrafluoroborate produces [Pt(EtXantphos) 2] 2+. Pt(EtXantphos 2] 2- undergoes two reversible one-electron reductions (E 1/2/II/I) = -0.81 V versus ferrocene and E 1/2(I/0) = ∼0.97 V), and HPt(EtXantphos 2] - undergoes a reversible one-electron oxidation E 1/2(II/III) = -0.23 V). These half-wave potentials and the pK a values of [HPt(EtXantphos 2] - and [(H) 2Pt(EtXantphos 2] 2- have been used to calculate five additional homolytic and heterolytic bond-dissociation free energies for these two hydride species and for [HPt(EtXantphos 2] 2- The extensive thermodynamic characterization of this hydride system provides useful insights into the factors controlling the reactivity of these complexes.

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