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Title: Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands

 [1]; ORCiD logo [1]
  1. Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Organometallics; Journal Volume: 36; Journal Issue: 17
Country of Publication:
United States

Citation Formats

Black, Rebecca E., and Jordan, Richard F. Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands. United States: N. p., 2017. Web. doi:10.1021/acs.organomet.7b00572.
Black, Rebecca E., & Jordan, Richard F. Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands. United States. doi:10.1021/acs.organomet.7b00572.
Black, Rebecca E., and Jordan, Richard F. 2017. "Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands". United States. doi:10.1021/acs.organomet.7b00572.
title = {Synthesis and Reactivity of Palladium(II) Alkyl Complexes that Contain Phosphine-cyclopentanesulfonate Ligands},
author = {Black, Rebecca E. and Jordan, Richard F.},
abstractNote = {},
doi = {10.1021/acs.organomet.7b00572},
journal = {Organometallics},
number = 17,
volume = 36,
place = {United States},
year = 2017,
month = 8
  • The syntheses and reactivities of yttrium alkyl and hydride complexes containing a sterically demanding, bis(heptamethylindenyl) ligand set are reported. The chloride complex Ind*2YCl(THF) (2, Ind* = heptamethylindenyl) was prepared by the reaction of Ind*Na (1, 2 equiv) with YCl3 in THF. Compound 2 was structurally characterized. Complex reaction mixtures were obtained when compound 2 was treated with KSi(SiMe3)3 or (THF)3LiSi(SiMe3)3, although 2 reacted readily with MeLi to yield the methyl complex Ind*2YMe(THF) (3). Treatment of 3 with H2 or PhSiH3 gave the base-stabilized hydride complex Ind*2YH(THF) (4). The base-free chloride complex Ind*2YCl (5) was synthesized by the reaction of 1more » (2 equiv) with YCl3 in toluene. Treatment of 2 with LiCH(SiMe3)2 yielded the base-free alkyl complex Ind*2YCH(SiMe3)2 (6). No reaction was observed between 6 and CH4, and complex reaction mixtures were obtained when 6 was treated with H2 or PhSiH3. However, when 6 was treated with H2 in the presence of THF, the transient hydride Ind*2YH was trapped as complex 4. The increased steric bulk of 6 leads to a slower reaction with PhSiH3 as compared to Cp*2YCH(SiMe3)2 (7).« less
  • trans-(PdR'/sub 2/(PR/sub 3/)/sub 2/) with a series of alkyl groups and tertiary phosphine ligands of various steric bulkiness (R' = Et, PR/sub 3/ = PMe/sub 2/Ph, PEt/sub 3/, PEt/sub 2/Ph, PMePh/sub 2/, PEtPh/sub 2/; R' = Pr, Bu, PR/sub 3/ = PMe/sub 2/Ph) are thermolyzed in solution by ..beta..-elimination processes liberating alkane and alkene in a 1:1 ratio. Kinetic studies on thermolysis of trans-(PdEt/sub 2/(PR/sub 3/)/sub 2/) revealed that they decompose obeying the first-order rate law with respect to the concentration of the palladium complexes. Thermolysis predominantly proceeds from the four-coordinated complex without dissociation of the tertiary phosphine ligand. Themore » minor parallel thermolysis pathway involving the dissociation of the phosphine is completely blocked by addition of the phosphine. Activation enthalpies for thermolysis of the ethylpalladium complexes having various steric bulkiness were virtually constant in the range of 26.0 +- 1.0 kcal/mol whereas activation entropies showed considerable variation with increasing bulkiness of the phosphine. Thermolysis of trans-(Pd(CH/sub 2/CD/sub 3/)/sub 2/(PMePh/sub 2/)/sub 2/) cleanly liberated CH/sub 2/==CD/sub 2/ and CH/sub 2/DCD/sub 3/ with a small isotope effect (k/sub H//k/sub D/ = 1.4 +- 0.1). The kinetic results together with examination of the molecular model suggest that the interaction between the bulky phosphine ligands and the ethyl groups causes the destabilization of the Pd-Et bonds. A thermolysis mechanism consistent with the kinetic results assuming an activation state distorted from the square-planar ground state is proposed. 6 figures, 5 tables.« less
  • The chemistry of high-valent ruthenium-oxo complexes has received much attention recently due to the potential applications of these complexes as oxidation catalysts and as oxygen atom transfer agents. In contrast, tertiary phosphine ligands have been primarily utilized in the syntheses of low-valent organometallic complexes, including those that have been used as both homogeneous and heterogeneous catalysts. Through the combination of these two dissimilar types of chemistry, the authors wish to report the first successful syntheses and characterization of ruthenium(IV)-oxo complexes that contain tertiary phosphine ligands in a position cis to the oxo ligand. In the syntheses of these phosphine-ruthenium(IV)-oxo complexes,more » oxidation of the tertiary phosphine ligand by the ruthenium(IV)-oxo moiety is avoided by initial generation of the ruthenium(II)-aquo-phosphine species, followed by cerium(IV) oxidation to the phosphine-ruthenium(IV)-oxo species. In this manner, no free tertiary phosphine ligand is exposed to a ruthenium(IV)-oxo complex, which would result in rapid phosphine oxidation. In addition, the coordinated phosphine ligands do not undergo any intramolecular or intermolecular oxidation upon formation of the ruthenium(IV)-oxo species. Notably, the reactivity of these complexes as oxidants toward organic substrates is substantially affected by simple variation of the substituents on the cis-phosphine ligand. 12 references, 1 figure.« less
  • Compounds of the type (ArylNHCH{sub 2}CH{sub 2}){sub 2}O (Aryl = 2,6-Me{sub 2}C{sub 6}H{sub 3} (H{sub 2}[1a])), 2,6-Et{sub 2}C{sub 6}H{sub 3} (H{sub 2}[1b]), 2,6-i-Pr{sub 2}C{sub 6}H{sub 3} (h{sub 2}[1c]) can be prepared by treating (TsOCH{sub 2}CH{sub 2}){sub 2}O (TsO = tosylate) with the lithium anilides in THF. [1a,b]TiCl{sub 2}, [1a,b]TiMe{sub 2}, [1a]Ti(CH{sub 2}Ph){sub 2}, [1a-c]M(NMe{sub 2}){sub 2} (M = Zr or Hf), [1a-c]MCl{sub 2}, and [1a-c]MR{sub 2} (R = Me, Et, i-Bu) were prepared. An X-ray study of [1a] Ti(CH{sub 2}Ph){sub 2} revealed the structure to be a distorted trigonal bipyramid (type B) in which the two amido nitrogens and onemore » benzyl ligand occupy equatorial positions. An X-ray study of [1a]ZrMe{sub 2} showed it to be a distorted trigonal bipyramid that contains axial amido groups (type A), while an X-ray study of [1c]HfEt{sub 2} revealed it to have a structure halfway between type A and type B, i.e,, a distorted square pyramid with one alkyl in the apical position. Zr and Hf dimethyl complexes that contain an oxygen donor or a sulfur donor ligand can be activated with [Ph{sub 3}C][B(C{sub 6}F{sub 5}){sub 4}] to yield efficient catalysts for polymerization of 1-hexene, although the molecular weight of the poly(1-hexene) chains is limited to {approximately}20,000-{approximately}25,000 under the conditions employed. Neither {l_brace}[1c]ZrMe(ether){r_brace}[B(C{sub 6}F{sub 5}){sub 4}] nor {l_brace}[1c]HfMe(ether){r_brace}[B(C{sub 6}F{sub 5}){sub 4}] will polymerize 1-hexene in C{sub 6}D{sub 5}Br at room temperature, and neither will polymerize ethylene readily at 1 atm and 25 C. It is proposed that a solvated five-coordinate cation must lose the solvent in order to react with an olefin and that {beta}-hydride elimination in the four-coordinate cation limits chain length.« less
  • A series of triply metal-metal bonded ditechnetium(II) phosphine complexes with the general formula Tc{sub 2}Cl{sub 4}(PR{sub 3}){sub 4} (PR{sub 3} = PEt{sub 3}, PPr{sup n}{sub 3}, PMePh{sub 2}, PMe{sub 2}Ph) have been prepared from mononuclear Tc(IV) precursors and fully characterized. Two-electron reduction of the Tc(IV) bis(phosphine) complexes TcCl{sub 4}(PR{sub 3}){sub 2} (PR{sub 3} = PEt{sub 3}, PPr{sup n}{sub 3}, PMePh{sub 2}, PMe{sub 2}Ph) with finely divided zinc in aromatic solvents or tetrahydrofuran results in the formation of the corresponding electron-rich triply bonded compounds Tc{sub 2}Cl{sub 4}(PR{sub 3}){sub 4} in high yield. These are the first phosphine complexes of technetium thatmore » possess a metal-metal bond. The solid-state structures of the PEt{sub 3}, PMe{sub 2}Ph, and PMePh{sub 2} derivatives have been investigated by X-ray crystallography and are described in detail. Similar to the analogous dirhenium(II) complexes, the molecules adopt an eclipsed M{sub 2}L{sub 8} conformation with approximate D{sub 2d} symmetry. The Tc-Tc bond lengths are 2.133(3), 2.127(1), and 2.1384(5) {angstrom} for Tc{sub 2}Cl{sub 4}(PEt{sub 3}){sub 4}, Tc{sub 2}Cl{sub 4}(PEt{sub 3}){sub 4}, Tc{sub 2}Cl{sub 4}(PMe{sub 2}Ph){sub 4}, and Tc{sub 2}Cl{sub 4}(PMePh{sub 2}){sub 4}, respectively. Structural and spectroscopic evidence indicates that these dimers contain an electron-rich Tc-Tc triple bond with a {sigma}{sup 2}-{pi}-{sup 4}{delta}{sup 2}{delta}*{sup 2} ground-state electronic configuration. Electrochemical studies reveal that each compound undergoes two reversible one-electron oxidation processes, which presumably produce the corresponding Tc{sub 2}{sup 5+} and Tc{sub 2}{sup 6+} dinuclear species. {sup 1}H HMR, {sup 31}P({sup 1}H) NMR, and UV-vis spectroscopic data are presented for each compound.« less