Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold­(III), platinum­(II), and palladium­(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl₄^–, AuBr₄^–, PtCl₄^–2, or Pd₂Cl₆^–2. In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine

Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold­(III), platinum­(II), and palladium­(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl₄^–, AuBr₄^–, PtCl₄^–2, or Pd₂Cl₆^–2. In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine

Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold­(III), platinum­(II), and palladium­(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl₄^–, AuBr₄^–, PtCl₄^–2, or Pd₂Cl₆^–2. In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine

Characterization of Metalloporphines: Iron(II) Carbonyls and Environmental Effects on νCO

The synthesis and characterization of two new iron­(II) porphine complexes is described. Porphine, the simplest porphyrin derivative, has been studied less than other synthetic porphyrins owing to synthetic difficulties and solubility issues. The subjects of this study are two six-coordinate iron­(II) species further coordinated by CO and an imidazole ligand (either 1-methylimidazole or 2-methylimidazole). The two species have very different CO stretching frequencies, with the 2-methylimidazole complex having a very low stretching frequency of 1923 cm^–1 compared to the more usual 1957 cm^–1 for the 1-methylimidazole derivative. The very low frequency is the result of environmental effects; the oxygen atom of the carbonyl forms a hydrogen bond with an adjacent coordinated imidazole with a hydrogen atom from the N–H group. The two species, with their differing C–O stretches, also display substantial differences in the values of the Fe–C and C–O bond distances, as determined by their X-ray structures. The two bond distances are strongly correlated (<i>R</i> = 0.98) in the direction expected for the classical π-backbonding model. The two bond distances are also strongly correlated with the C–O stretching frequencies. We can conclude that the Fe–C and C–O stretches are quite representative of the observed bond distances; their stretching frequencies are not affected by substantial mode mixing

Bi₇^3–: The Missing Family Member, Finally Isolated and Characterized

The synthesis and structure of Bi₇^3–, the only missing member of the family of heptanuclear pnictogen cluster anions Pn₇^3– (Pn = pnictogen, a group 15 element excluding the unique nitrogen), is reported. The new species is synthesized by oxidation of a solution of K₅Bi₄ by the solvent pyridine in the presence of (C₆H₆)­Cr­(CO)₃. The existence of the species in solution is confirmed by electrospray mass spectrometry, while its structure is elucidated by single-crystal X-ray diffraction in the compound [K­(2,2,2-crypt)]₃Bi₇·2py (monoclinic, <i>P</i>2₁/<i>n</i>, <i>a</i> = 13.8739(13) Å, <i>b</i> = 24.878(2) Å, <i>c</i> = 26.401(2) Å, β = 96.353(4)°, <i>V</i> = 9056.5(14) ų, <i>Z</i> = 4, and R1/wR2 = 0.0636/0.1390 for the observed data and 0.0901/0.1541 for all data)

Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold­(III), platinum­(II), and palladium­(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl₄^–, AuBr₄^–, PtCl₄^–2, or Pd₂Cl₆^–2. In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine

Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold­(III), platinum­(II), and palladium­(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl₄^–, AuBr₄^–, PtCl₄^–2, or Pd₂Cl₆^–2. In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine

Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold­(III), platinum­(II), and palladium­(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl₄^–, AuBr₄^–, PtCl₄^–2, or Pd₂Cl₆^–2. In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine

Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold­(III), platinum­(II), and palladium­(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl₄^–, AuBr₄^–, PtCl₄^–2, or Pd₂Cl₆^–2. In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine

Iron(III)-Templated Macrolactonization of Trihydroxamate Siderophores

A method was developed to synthesize macrocyclic trihydroxamate siderophores using optimized Yamaguchi macrolactonization conditions. The natural ability of siderophores to bind iron(III) was exploited to template the reactions and allowed for rapid reaction rates, high product conversions, and the formation of large macrolactone rings up to 35 atoms. An X-ray structure of a 33-membered macrolactone siderophore–Fe(III) complex is presented