Selective Au–C Cleavage in (C^∧N^∧C)Au(III) Aryl and Alkyl Pincer Complexes

Treatment of gold­(III) pincer complexes (C^∧N^∧C)*AuX with trifluoroacetic acid (X = C₆F₅, thiophenyl, Me, Et) or of (C^∧N^∧C)*AuOAc^F with AgOAc^F/arylboronic acids leads to the selective cleavage of a C–Au bond under mild conditions to give the bidentate complexes (HC-C^∧N)*Au­(X)­(OAc^F) [(C^∧N^∧C)* = 2,6-(C₆H₃Bu^t)₂pyridine]. Alkylation of (C^∧N^∧C)*Au­(OAc^F) with AlR₃ (R = Me, Et) proved to be a high-yielding route to gold­(III) alkyls. Au–C cleavage significantly influences reactivity, e.g., with boronic acids. The photoemission of the cleavage product (HC-C^∧N)*Au­(C₆H₄F)­(OAc^F) is about an order of magnitude more intense than that of its tridentate parent compound

Metal Hydrides Form Halogen Bonds: Measurement of Energetics of Binding

The formation of halogen bonds from iodopentafluorobenzene and 1-iodoperfluorohexane to a series of bis­(η⁵-cyclopentadienyl)­metal hydrides (Cp₂TaH₃, <b>1</b>; Cp₂MH₂, M = Mo, <b>2</b>, M = W, <b>3</b>; Cp₂ReH, <b>4</b>; Cp₂Ta­(H)­CO, <b>5</b>; Cp = η⁵-cyclopentadienyl) is demonstrated by ¹H NMR spectroscopy. Interaction enthalpies and entropies for complex <b>1</b> with C₆F₅I and C₆F₁₃I are reported (Δ<i>H</i>° = −10.9 ± 0.4 and −11.8 ± 0.3 kJ/mol; Δ<i>S</i>° = −38 ± 2 and −34 ± 2 J/(mol·K), respectively) and found to be stronger than those for <b>1</b> with the hydrogen-bond donor indole (Δ<i>H</i>° = −7.3 ± 0.1 kJ/mol, Δ<i>S</i>° = −24 ± 1 J/(mol·K)). For the more reactive complexes <b>2</b>–<b>5</b>, measurements are limited to determination of their low-temperature (212 K) association constants with C₆F₅I as 2.9 ± 0.2, 2.5 ± 0.1, <1.5, and 12.5 ± 0.3 M^–1, respectively

Monomeric Rhodium(II) Complexes Supported by a Diarylamido/Bis(phosphine) PNP Pincer Ligand and Their Reactivity Toward Dihydrogen

A rhodium­(II) complex of a diarylamido/bis­(phosphine) PNP pincer ligand, (PNP)­Rh­(OTf) (<b>2</b>, where OTf = O₃SCF₃ and PNP = [κ³-<i>P</i>,<i>N</i>,<i>P</i>-(4-Me-2-(ⁱPr₂P)-C₆H₃)₂N]), has been prepared by oxidation of the rhodium­(I) precursor (PNP)­Rh­(H₂CCHBu^t) (<b>1</b>) with AgOTf. A series of related rhodium­(II) complexes of the general formula (PNP)­Rh­(X) (where X = OAc (<b>3</b>), OSiPh₃ (<b>4</b>), OC₆H₄F (<b>5</b>), Cl (<b>6</b>)) was synthesized via simple anion metathesis reactions starting from <b>2</b>. In addition, complexes <b>3</b> and <b>6</b> could be prepared by hydrogen atom abstraction from (PNP)­Rh­(H)­(OAc) (<b>7</b>) or (PNP)­Rh­(H)­(Cl) (<b>8</b>) with TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)­oxyl). Solid-state X-ray structures of compounds <b>2</b>–<b>6</b> revealed an approximately square-planar environment about Rh. Analysis of the structural features of <b>2</b>–<b>6</b>, EPR spectroscopic data, and DFT computational studies are most consistent with a +2 oxidation state for rhodium. Reactions of <b>2</b>, <b>3</b>, <b>5</b>, and <b>6</b> with H₂ were explored. The reaction of <b>2</b> with H₂ gave the new complex (PN­(H)­P)­Rh­(H)₂(OTf) (<b>9</b>), and the reaction of <b>3</b> with H₂ produced (PNP)­Rh­(H)­(OAc) (<b>7</b>), whereas the reaction of <b>5</b> with H₂ gave the known (PNP)­Rh­(H₂) (<b>10</b>), all with complete consumption of the starting rhodium­(II) complexes. In contrast, the reaction of <b>6</b> with H₂ produced a mixture of (PNP)­Rh­(H)­(Cl) (<b>8</b>) and (PN­(H)­P)­Rh­(H)₂(Cl) (<b>11</b>) in apparent equilibrium with <b>6</b> and H₂. (PNP)­Rh­(H₂) (<b>10</b>) was identified as an elongated dihydrogen complex

Monomeric Rhodium(II) Complexes Supported by a Diarylamido/Bis(phosphine) PNP Pincer Ligand and Their Reactivity Toward Dihydrogen

A rhodium­(II) complex of a diarylamido/bis­(phosphine) PNP pincer ligand, (PNP)­Rh­(OTf) (<b>2</b>, where OTf = O₃SCF₃ and PNP = [κ³-<i>P</i>,<i>N</i>,<i>P</i>-(4-Me-2-(ⁱPr₂P)-C₆H₃)₂N]), has been prepared by oxidation of the rhodium­(I) precursor (PNP)­Rh­(H₂CCHBu^t) (<b>1</b>) with AgOTf. A series of related rhodium­(II) complexes of the general formula (PNP)­Rh­(X) (where X = OAc (<b>3</b>), OSiPh₃ (<b>4</b>), OC₆H₄F (<b>5</b>), Cl (<b>6</b>)) was synthesized via simple anion metathesis reactions starting from <b>2</b>. In addition, complexes <b>3</b> and <b>6</b> could be prepared by hydrogen atom abstraction from (PNP)­Rh­(H)­(OAc) (<b>7</b>) or (PNP)­Rh­(H)­(Cl) (<b>8</b>) with TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)­oxyl). Solid-state X-ray structures of compounds <b>2</b>–<b>6</b> revealed an approximately square-planar environment about Rh. Analysis of the structural features of <b>2</b>–<b>6</b>, EPR spectroscopic data, and DFT computational studies are most consistent with a +2 oxidation state for rhodium. Reactions of <b>2</b>, <b>3</b>, <b>5</b>, and <b>6</b> with H₂ were explored. The reaction of <b>2</b> with H₂ gave the new complex (PN­(H)­P)­Rh­(H)₂(OTf) (<b>9</b>), and the reaction of <b>3</b> with H₂ produced (PNP)­Rh­(H)­(OAc) (<b>7</b>), whereas the reaction of <b>5</b> with H₂ gave the known (PNP)­Rh­(H₂) (<b>10</b>), all with complete consumption of the starting rhodium­(II) complexes. In contrast, the reaction of <b>6</b> with H₂ produced a mixture of (PNP)­Rh­(H)­(Cl) (<b>8</b>) and (PN­(H)­P)­Rh­(H)₂(Cl) (<b>11</b>) in apparent equilibrium with <b>6</b> and H₂. (PNP)­Rh­(H₂) (<b>10</b>) was identified as an elongated dihydrogen complex

Monomeric Rhodium(II) Complexes Supported by a Diarylamido/Bis(phosphine) PNP Pincer Ligand and Their Reactivity Toward Dihydrogen

A rhodium­(II) complex of a diarylamido/bis­(phosphine) PNP pincer ligand, (PNP)­Rh­(OTf) (<b>2</b>, where OTf = O₃SCF₃ and PNP = [κ³-<i>P</i>,<i>N</i>,<i>P</i>-(4-Me-2-(ⁱPr₂P)-C₆H₃)₂N]), has been prepared by oxidation of the rhodium­(I) precursor (PNP)­Rh­(H₂CCHBu^t) (<b>1</b>) with AgOTf. A series of related rhodium­(II) complexes of the general formula (PNP)­Rh­(X) (where X = OAc (<b>3</b>), OSiPh₃ (<b>4</b>), OC₆H₄F (<b>5</b>), Cl (<b>6</b>)) was synthesized via simple anion metathesis reactions starting from <b>2</b>. In addition, complexes <b>3</b> and <b>6</b> could be prepared by hydrogen atom abstraction from (PNP)­Rh­(H)­(OAc) (<b>7</b>) or (PNP)­Rh­(H)­(Cl) (<b>8</b>) with TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)­oxyl). Solid-state X-ray structures of compounds <b>2</b>–<b>6</b> revealed an approximately square-planar environment about Rh. Analysis of the structural features of <b>2</b>–<b>6</b>, EPR spectroscopic data, and DFT computational studies are most consistent with a +2 oxidation state for rhodium. Reactions of <b>2</b>, <b>3</b>, <b>5</b>, and <b>6</b> with H₂ were explored. The reaction of <b>2</b> with H₂ gave the new complex (PN­(H)­P)­Rh­(H)₂(OTf) (<b>9</b>), and the reaction of <b>3</b> with H₂ produced (PNP)­Rh­(H)­(OAc) (<b>7</b>), whereas the reaction of <b>5</b> with H₂ gave the known (PNP)­Rh­(H₂) (<b>10</b>), all with complete consumption of the starting rhodium­(II) complexes. In contrast, the reaction of <b>6</b> with H₂ produced a mixture of (PNP)­Rh­(H)­(Cl) (<b>8</b>) and (PN­(H)­P)­Rh­(H)₂(Cl) (<b>11</b>) in apparent equilibrium with <b>6</b> and H₂. (PNP)­Rh­(H₂) (<b>10</b>) was identified as an elongated dihydrogen complex

Monomeric Rhodium(II) Complexes Supported by a Diarylamido/Bis(phosphine) PNP Pincer Ligand and Their Reactivity Toward Dihydrogen

A rhodium­(II) complex of a diarylamido/bis­(phosphine) PNP pincer ligand, (PNP)­Rh­(OTf) (<b>2</b>, where OTf = O₃SCF₃ and PNP = [κ³-<i>P</i>,<i>N</i>,<i>P</i>-(4-Me-2-(ⁱPr₂P)-C₆H₃)₂N]), has been prepared by oxidation of the rhodium­(I) precursor (PNP)­Rh­(H₂CCHBu^t) (<b>1</b>) with AgOTf. A series of related rhodium­(II) complexes of the general formula (PNP)­Rh­(X) (where X = OAc (<b>3</b>), OSiPh₃ (<b>4</b>), OC₆H₄F (<b>5</b>), Cl (<b>6</b>)) was synthesized via simple anion metathesis reactions starting from <b>2</b>. In addition, complexes <b>3</b> and <b>6</b> could be prepared by hydrogen atom abstraction from (PNP)­Rh­(H)­(OAc) (<b>7</b>) or (PNP)­Rh­(H)­(Cl) (<b>8</b>) with TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)­oxyl). Solid-state X-ray structures of compounds <b>2</b>–<b>6</b> revealed an approximately square-planar environment about Rh. Analysis of the structural features of <b>2</b>–<b>6</b>, EPR spectroscopic data, and DFT computational studies are most consistent with a +2 oxidation state for rhodium. Reactions of <b>2</b>, <b>3</b>, <b>5</b>, and <b>6</b> with H₂ were explored. The reaction of <b>2</b> with H₂ gave the new complex (PN­(H)­P)­Rh­(H)₂(OTf) (<b>9</b>), and the reaction of <b>3</b> with H₂ produced (PNP)­Rh­(H)­(OAc) (<b>7</b>), whereas the reaction of <b>5</b> with H₂ gave the known (PNP)­Rh­(H₂) (<b>10</b>), all with complete consumption of the starting rhodium­(II) complexes. In contrast, the reaction of <b>6</b> with H₂ produced a mixture of (PNP)­Rh­(H)­(Cl) (<b>8</b>) and (PN­(H)­P)­Rh­(H)₂(Cl) (<b>11</b>) in apparent equilibrium with <b>6</b> and H₂. (PNP)­Rh­(H₂) (<b>10</b>) was identified as an elongated dihydrogen complex

Monomeric Rhodium(II) Complexes Supported by a Diarylamido/Bis(phosphine) PNP Pincer Ligand and Their Reactivity Toward Dihydrogen

A rhodium­(II) complex of a diarylamido/bis­(phosphine) PNP pincer ligand, (PNP)­Rh­(OTf) (<b>2</b>, where OTf = O₃SCF₃ and PNP = [κ³-<i>P</i>,<i>N</i>,<i>P</i>-(4-Me-2-(ⁱPr₂P)-C₆H₃)₂N]), has been prepared by oxidation of the rhodium­(I) precursor (PNP)­Rh­(H₂CCHBu^t) (<b>1</b>) with AgOTf. A series of related rhodium­(II) complexes of the general formula (PNP)­Rh­(X) (where X = OAc (<b>3</b>), OSiPh₃ (<b>4</b>), OC₆H₄F (<b>5</b>), Cl (<b>6</b>)) was synthesized via simple anion metathesis reactions starting from <b>2</b>. In addition, complexes <b>3</b> and <b>6</b> could be prepared by hydrogen atom abstraction from (PNP)­Rh­(H)­(OAc) (<b>7</b>) or (PNP)­Rh­(H)­(Cl) (<b>8</b>) with TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)­oxyl). Solid-state X-ray structures of compounds <b>2</b>–<b>6</b> revealed an approximately square-planar environment about Rh. Analysis of the structural features of <b>2</b>–<b>6</b>, EPR spectroscopic data, and DFT computational studies are most consistent with a +2 oxidation state for rhodium. Reactions of <b>2</b>, <b>3</b>, <b>5</b>, and <b>6</b> with H₂ were explored. The reaction of <b>2</b> with H₂ gave the new complex (PN­(H)­P)­Rh­(H)₂(OTf) (<b>9</b>), and the reaction of <b>3</b> with H₂ produced (PNP)­Rh­(H)­(OAc) (<b>7</b>), whereas the reaction of <b>5</b> with H₂ gave the known (PNP)­Rh­(H₂) (<b>10</b>), all with complete consumption of the starting rhodium­(II) complexes. In contrast, the reaction of <b>6</b> with H₂ produced a mixture of (PNP)­Rh­(H)­(Cl) (<b>8</b>) and (PN­(H)­P)­Rh­(H)₂(Cl) (<b>11</b>) in apparent equilibrium with <b>6</b> and H₂. (PNP)­Rh­(H₂) (<b>10</b>) was identified as an elongated dihydrogen complex

Monomeric Rhodium(II) Complexes Supported by a Diarylamido/Bis(phosphine) PNP Pincer Ligand and Their Reactivity Toward Dihydrogen

A rhodium­(II) complex of a diarylamido/bis­(phosphine) PNP pincer ligand, (PNP)­Rh­(OTf) (<b>2</b>, where OTf = O₃SCF₃ and PNP = [κ³-<i>P</i>,<i>N</i>,<i>P</i>-(4-Me-2-(ⁱPr₂P)-C₆H₃)₂N]), has been prepared by oxidation of the rhodium­(I) precursor (PNP)­Rh­(H₂CCHBu^t) (<b>1</b>) with AgOTf. A series of related rhodium­(II) complexes of the general formula (PNP)­Rh­(X) (where X = OAc (<b>3</b>), OSiPh₃ (<b>4</b>), OC₆H₄F (<b>5</b>), Cl (<b>6</b>)) was synthesized via simple anion metathesis reactions starting from <b>2</b>. In addition, complexes <b>3</b> and <b>6</b> could be prepared by hydrogen atom abstraction from (PNP)­Rh­(H)­(OAc) (<b>7</b>) or (PNP)­Rh­(H)­(Cl) (<b>8</b>) with TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)­oxyl). Solid-state X-ray structures of compounds <b>2</b>–<b>6</b> revealed an approximately square-planar environment about Rh. Analysis of the structural features of <b>2</b>–<b>6</b>, EPR spectroscopic data, and DFT computational studies are most consistent with a +2 oxidation state for rhodium. Reactions of <b>2</b>, <b>3</b>, <b>5</b>, and <b>6</b> with H₂ were explored. The reaction of <b>2</b> with H₂ gave the new complex (PN­(H)­P)­Rh­(H)₂(OTf) (<b>9</b>), and the reaction of <b>3</b> with H₂ produced (PNP)­Rh­(H)­(OAc) (<b>7</b>), whereas the reaction of <b>5</b> with H₂ gave the known (PNP)­Rh­(H₂) (<b>10</b>), all with complete consumption of the starting rhodium­(II) complexes. In contrast, the reaction of <b>6</b> with H₂ produced a mixture of (PNP)­Rh­(H)­(Cl) (<b>8</b>) and (PN­(H)­P)­Rh­(H)₂(Cl) (<b>11</b>) in apparent equilibrium with <b>6</b> and H₂. (PNP)­Rh­(H₂) (<b>10</b>) was identified as an elongated dihydrogen complex

Monomeric Rhodium(II) Complexes Supported by a Diarylamido/Bis(phosphine) PNP Pincer Ligand and Their Reactivity Toward Dihydrogen

A rhodium­(II) complex of a diarylamido/bis­(phosphine) PNP pincer ligand, (PNP)­Rh­(OTf) (<b>2</b>, where OTf = O₃SCF₃ and PNP = [κ³-<i>P</i>,<i>N</i>,<i>P</i>-(4-Me-2-(ⁱPr₂P)-C₆H₃)₂N]), has been prepared by oxidation of the rhodium­(I) precursor (PNP)­Rh­(H₂CCHBu^t) (<b>1</b>) with AgOTf. A series of related rhodium­(II) complexes of the general formula (PNP)­Rh­(X) (where X = OAc (<b>3</b>), OSiPh₃ (<b>4</b>), OC₆H₄F (<b>5</b>), Cl (<b>6</b>)) was synthesized via simple anion metathesis reactions starting from <b>2</b>. In addition, complexes <b>3</b> and <b>6</b> could be prepared by hydrogen atom abstraction from (PNP)­Rh­(H)­(OAc) (<b>7</b>) or (PNP)­Rh­(H)­(Cl) (<b>8</b>) with TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)­oxyl). Solid-state X-ray structures of compounds <b>2</b>–<b>6</b> revealed an approximately square-planar environment about Rh. Analysis of the structural features of <b>2</b>–<b>6</b>, EPR spectroscopic data, and DFT computational studies are most consistent with a +2 oxidation state for rhodium. Reactions of <b>2</b>, <b>3</b>, <b>5</b>, and <b>6</b> with H₂ were explored. The reaction of <b>2</b> with H₂ gave the new complex (PN­(H)­P)­Rh­(H)₂(OTf) (<b>9</b>), and the reaction of <b>3</b> with H₂ produced (PNP)­Rh­(H)­(OAc) (<b>7</b>), whereas the reaction of <b>5</b> with H₂ gave the known (PNP)­Rh­(H₂) (<b>10</b>), all with complete consumption of the starting rhodium­(II) complexes. In contrast, the reaction of <b>6</b> with H₂ produced a mixture of (PNP)­Rh­(H)­(Cl) (<b>8</b>) and (PN­(H)­P)­Rh­(H)₂(Cl) (<b>11</b>) in apparent equilibrium with <b>6</b> and H₂. (PNP)­Rh­(H₂) (<b>10</b>) was identified as an elongated dihydrogen complex

An efficient and scalable process to produce morpholine-d₈

<p>Incorporation of isotopes has long been used as a research tool to label carbons and elucidate biochemical pathways. More recently, H→D exchange has led to analogs of therapeutic agents with improved metabolic stability and properties. Such compounds also have the potential for an improved drug/drug interaction profile and may even avoid the formation of toxic metabolites. Hence, a clear need for an efficient access to deuterated intermediates on large scale has emerged. In the context of an ongoing drug discovery program, we required large quantities of morpholine-d₈. We herein report the successful optimization of a one-pot process allowing a near complete exchange of all methylene hydrogens in morpholine to deuterium atoms using D₂O as the sole source of deuterium and Raney Nickel as catalyst. This facile and safe protocol will be used to scale up the synthesis of morpholine-d₈ in due course.</p