Review of the conference Dante and Music : University of Pennsylvania, Philadelphia, 5-6 November 2015

A general and efficient synthesis of 4,9-dihydro-1<i>H</i>-carbazoles from 3-allenylmethylindoles is reported. The process, catalyzed by a cationic gold­(I) complex, involves a formal C2–H bond activation of the indole unit by reaction with the allene. The nature of the substituents at the allylic and terminal positions of the allene moiety has a crucial effect on the regioselectivity of the cyclization, which is also influenced by the catalyst and the solvent employed. Moreover, some evidence of the contribution of different reaction routes is provided, which led us to propose a plausible multipathway mechanism consistent with all of the results described

Search for pair-produced resonances decaying to quark pairs in proton-proton collisions at root s=13 TeV

A general search for the pair production of resonances, each decaying to two quarks, is reported. The search is conducted separately for heavier resonances (masses above 400 GeV), where each of the four final-state quarks generates a hadronic jet resulting in a four-jet signature, and for lighter resonances (masses between 80 and 400 GeV), where the pair of quarks from each resonance is collimated and reconstructed as a single jet resulting in a two-jet signature. In addition, a b-tagged selection is applied to target resonances with a bottom quark in the final state. The analysis uses data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb(-1), from proton-proton collisions at a center-of-mass energy of 13 TeV. The mass spectra are analyzed for the presence of new resonances, and are found to be consistent with standard model expectations. The results are interpreted in the framework of R-parity-violating supersymmetry assuming the pair production of scalar top quarks decaying via the hadronic coupling lambda ''(312) or lambda ''(323) and upper limits on the cross section as a function of the top squark mass are set. These results probe a wider range of masses than previously explored at the LHC, and extend the top squark mass limits in the (t) over tilde -> qq' scenario.Peer reviewe

Amidinatogermylene Metal Complexes as Homogeneous Catalysts in Alcoholic Media

A series of transition-metal complexes containing the bulky amidinatogermylene Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu (<b>1</b>; ^<i>t</i>Bu₂bzam = <i>N</i>,<i>N</i>′-bis­(<i>tert-</i>butyl)­benzamidinate) as a ligand have been prepared and characterized. While the hydrolytic degradation of the germylene ligand of the square-planar complexes [MCl­(η⁴-cod)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (M = Rh (<b>2</b>), Ir (<b>3</b>); cod = 1,5-cyclooctadiene) and [PdCl­(η³-metallyl)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (<b>4</b>; metallyl = 2-methylallyl) is slow but clearly evident in carefully dried aprotic solvents, the octahedral complexes [RuCl₂(η⁶-cym)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (<b>5</b>; cym = <i>p</i>-cymene) and [IrCl₂(η⁵-Cp*)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (<b>6</b>; Cp* = pentamethylcyclopentadienyl) have proven to be stable even in alcoholic solvents. These latter complexes have been tested as catalyst precursors of reactions involving alcohols as substrates and/or solvents, and remarkably, they have been found to be active in the transfer hydrogenation of cyclohexanone with isopropyl alcohol (<b>5</b> and <b>6</b>), the <i>N</i>-alkylation of aniline with benzyl alcohol (<b>5</b> and <b>6</b>), and the deuteriation of acetophenone with CD₃OD (<b>6</b>). The use of heavier carbene metal complexes as catalyst precursors of reactions involving alcohols as solvents is unprecedented

Amidinatogermylene Metal Complexes as Homogeneous Catalysts in Alcoholic Media

A series of transition-metal complexes containing the bulky amidinatogermylene Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu (<b>1</b>; ^<i>t</i>Bu₂bzam = <i>N</i>,<i>N</i>′-bis­(<i>tert-</i>butyl)­benzamidinate) as a ligand have been prepared and characterized. While the hydrolytic degradation of the germylene ligand of the square-planar complexes [MCl­(η⁴-cod)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (M = Rh (<b>2</b>), Ir (<b>3</b>); cod = 1,5-cyclooctadiene) and [PdCl­(η³-metallyl)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (<b>4</b>; metallyl = 2-methylallyl) is slow but clearly evident in carefully dried aprotic solvents, the octahedral complexes [RuCl₂(η⁶-cym)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (<b>5</b>; cym = <i>p</i>-cymene) and [IrCl₂(η⁵-Cp*)­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (<b>6</b>; Cp* = pentamethylcyclopentadienyl) have proven to be stable even in alcoholic solvents. These latter complexes have been tested as catalyst precursors of reactions involving alcohols as substrates and/or solvents, and remarkably, they have been found to be active in the transfer hydrogenation of cyclohexanone with isopropyl alcohol (<b>5</b> and <b>6</b>), the <i>N</i>-alkylation of aniline with benzyl alcohol (<b>5</b> and <b>6</b>), and the deuteriation of acetophenone with CD₃OD (<b>6</b>). The use of heavier carbene metal complexes as catalyst precursors of reactions involving alcohols as solvents is unprecedented

Diaminogermylene and Diaminostannylene Derivatives of Gold(I): Novel AuM and AuM₂ (M = Ge, Sn) Complexes

The reactions of [AuCl­(THT)] (THT = tetrahydrothiophene) with 1 equiv of the group 14 diaminometalenes M­(HMDS)₂ [M = Ge, Sn; HMDS = N­(SiMe₃)₂] lead to [Au­{MCl­(HMDS)₂}­(THT)] [M = Ge (<b>1</b>), Sn (<b>2</b>)], which contain a metalate­(II) ligand that arises from insertion of the corresponding M­(HMDS)₂ reagent into the Au–Cl bond of the gold­(I) reagent. While compound <b>1</b> reacts with more Ge­(HMDS)₂ to give the germanate–germylene derivative [Au­{GeCl­(HMDS)₂}­{Ge­(HMDS)₂}] (<b>3</b>), which results from substitution of Ge­(HMDS)₂ for the THT ligand of <b>1</b>, an analogous treatment of compound <b>2</b> with Sn­(HMDS)₂ gives the stannate–stannylene derivative [Au­{SnCl­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] (<b>4</b>), which has a THT ligand attached to the stannylene tin atom and which, in solution at room temperature, participates in a dynamic process that makes its two Sn­(HMDS)₂ fragments equivalent (on the NMR time scale). A similar dynamic process has not been observed for the AuGe₂ compound <b>3</b> or for the AuSn₂ derivatives [Au­{SnR­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] [R = Bu (<b>5</b>), HMDS (<b>6</b>)], which have been prepared by treating complex <b>4</b> with LiR. The structures of compounds <b>1</b> and <b>3</b>–<b>6</b> have been determined by X-ray diffraction

Diaminogermylene and Diaminostannylene Derivatives of Gold(I): Novel AuM and AuM₂ (M = Ge, Sn) Complexes

The reactions of [AuCl­(THT)] (THT = tetrahydrothiophene) with 1 equiv of the group 14 diaminometalenes M­(HMDS)₂ [M = Ge, Sn; HMDS = N­(SiMe₃)₂] lead to [Au­{MCl­(HMDS)₂}­(THT)] [M = Ge (<b>1</b>), Sn (<b>2</b>)], which contain a metalate­(II) ligand that arises from insertion of the corresponding M­(HMDS)₂ reagent into the Au–Cl bond of the gold­(I) reagent. While compound <b>1</b> reacts with more Ge­(HMDS)₂ to give the germanate–germylene derivative [Au­{GeCl­(HMDS)₂}­{Ge­(HMDS)₂}] (<b>3</b>), which results from substitution of Ge­(HMDS)₂ for the THT ligand of <b>1</b>, an analogous treatment of compound <b>2</b> with Sn­(HMDS)₂ gives the stannate–stannylene derivative [Au­{SnCl­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] (<b>4</b>), which has a THT ligand attached to the stannylene tin atom and which, in solution at room temperature, participates in a dynamic process that makes its two Sn­(HMDS)₂ fragments equivalent (on the NMR time scale). A similar dynamic process has not been observed for the AuGe₂ compound <b>3</b> or for the AuSn₂ derivatives [Au­{SnR­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] [R = Bu (<b>5</b>), HMDS (<b>6</b>)], which have been prepared by treating complex <b>4</b> with LiR. The structures of compounds <b>1</b> and <b>3</b>–<b>6</b> have been determined by X-ray diffraction

Diaminogermylene and Diaminostannylene Derivatives of Gold(I): Novel AuM and AuM₂ (M = Ge, Sn) Complexes

The reactions of [AuCl­(THT)] (THT = tetrahydrothiophene) with 1 equiv of the group 14 diaminometalenes M­(HMDS)₂ [M = Ge, Sn; HMDS = N­(SiMe₃)₂] lead to [Au­{MCl­(HMDS)₂}­(THT)] [M = Ge (<b>1</b>), Sn (<b>2</b>)], which contain a metalate­(II) ligand that arises from insertion of the corresponding M­(HMDS)₂ reagent into the Au–Cl bond of the gold­(I) reagent. While compound <b>1</b> reacts with more Ge­(HMDS)₂ to give the germanate–germylene derivative [Au­{GeCl­(HMDS)₂}­{Ge­(HMDS)₂}] (<b>3</b>), which results from substitution of Ge­(HMDS)₂ for the THT ligand of <b>1</b>, an analogous treatment of compound <b>2</b> with Sn­(HMDS)₂ gives the stannate–stannylene derivative [Au­{SnCl­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] (<b>4</b>), which has a THT ligand attached to the stannylene tin atom and which, in solution at room temperature, participates in a dynamic process that makes its two Sn­(HMDS)₂ fragments equivalent (on the NMR time scale). A similar dynamic process has not been observed for the AuGe₂ compound <b>3</b> or for the AuSn₂ derivatives [Au­{SnR­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] [R = Bu (<b>5</b>), HMDS (<b>6</b>)], which have been prepared by treating complex <b>4</b> with LiR. The structures of compounds <b>1</b> and <b>3</b>–<b>6</b> have been determined by X-ray diffraction

Diaminogermylene and Diaminostannylene Derivatives of Gold(I): Novel AuM and AuM₂ (M = Ge, Sn) Complexes

The reactions of [AuCl­(THT)] (THT = tetrahydrothiophene) with 1 equiv of the group 14 diaminometalenes M­(HMDS)₂ [M = Ge, Sn; HMDS = N­(SiMe₃)₂] lead to [Au­{MCl­(HMDS)₂}­(THT)] [M = Ge (<b>1</b>), Sn (<b>2</b>)], which contain a metalate­(II) ligand that arises from insertion of the corresponding M­(HMDS)₂ reagent into the Au–Cl bond of the gold­(I) reagent. While compound <b>1</b> reacts with more Ge­(HMDS)₂ to give the germanate–germylene derivative [Au­{GeCl­(HMDS)₂}­{Ge­(HMDS)₂}] (<b>3</b>), which results from substitution of Ge­(HMDS)₂ for the THT ligand of <b>1</b>, an analogous treatment of compound <b>2</b> with Sn­(HMDS)₂ gives the stannate–stannylene derivative [Au­{SnCl­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] (<b>4</b>), which has a THT ligand attached to the stannylene tin atom and which, in solution at room temperature, participates in a dynamic process that makes its two Sn­(HMDS)₂ fragments equivalent (on the NMR time scale). A similar dynamic process has not been observed for the AuGe₂ compound <b>3</b> or for the AuSn₂ derivatives [Au­{SnR­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] [R = Bu (<b>5</b>), HMDS (<b>6</b>)], which have been prepared by treating complex <b>4</b> with LiR. The structures of compounds <b>1</b> and <b>3</b>–<b>6</b> have been determined by X-ray diffraction

Diaminogermylene and Diaminostannylene Derivatives of Gold(I): Novel AuM and AuM₂ (M = Ge, Sn) Complexes

The reactions of [AuCl­(THT)] (THT = tetrahydrothiophene) with 1 equiv of the group 14 diaminometalenes M­(HMDS)₂ [M = Ge, Sn; HMDS = N­(SiMe₃)₂] lead to [Au­{MCl­(HMDS)₂}­(THT)] [M = Ge (<b>1</b>), Sn (<b>2</b>)], which contain a metalate­(II) ligand that arises from insertion of the corresponding M­(HMDS)₂ reagent into the Au–Cl bond of the gold­(I) reagent. While compound <b>1</b> reacts with more Ge­(HMDS)₂ to give the germanate–germylene derivative [Au­{GeCl­(HMDS)₂}­{Ge­(HMDS)₂}] (<b>3</b>), which results from substitution of Ge­(HMDS)₂ for the THT ligand of <b>1</b>, an analogous treatment of compound <b>2</b> with Sn­(HMDS)₂ gives the stannate–stannylene derivative [Au­{SnCl­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] (<b>4</b>), which has a THT ligand attached to the stannylene tin atom and which, in solution at room temperature, participates in a dynamic process that makes its two Sn­(HMDS)₂ fragments equivalent (on the NMR time scale). A similar dynamic process has not been observed for the AuGe₂ compound <b>3</b> or for the AuSn₂ derivatives [Au­{SnR­(HMDS)₂}­{Sn­(HMDS)₂(THT)}] [R = Bu (<b>5</b>), HMDS (<b>6</b>)], which have been prepared by treating complex <b>4</b> with LiR. The structures of compounds <b>1</b> and <b>3</b>–<b>6</b> have been determined by X-ray diffraction

Reactivity Studies on a Binuclear Ruthenium(0) Complex Equipped with a Bridging κ²<i>N</i>,<i>Ge</i>-Amidinatogermylene Ligand

The amidinatogermylene-bridged diruthenium(0) complex [Ru₂{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­(CO)₇] (<b>2</b>; ^<i>i</i>Pr₂bzam = <i>N</i>,<i>N</i>′-bis­(<i>iso-</i>propyl)­benzamidinate; HMDS = N­(SiMe₃)₂) reacted at room temperature with ^<i>t</i>BuNC and PMe₃ to give [Ru₂{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­(L)­(CO)₆] (L = ^<i>t</i>BuNC, <b>3</b>; PMe₃, <b>4</b>), which contain the new ligand in an axial position on the Ru atom that is not attached to the amidinato fragment. At 70 °C, <b>2</b> reacted with PPh₃, PMe₃, dppm, and dppe to give the equatorially substituted derivatives [Ru₂{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­(L)­(CO)₆] (L = PPh₃, <b>5</b>; PMe₃, <b>6</b>) and [Ru₂{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­(μ–κ²<i>P,P</i>′-L₂)­(CO)₅] (L₂ = dppm, <b>7</b>; dppe, <b>8</b>). HSiEt₃ and HSnPh₃ were oxidatively added to complex <b>2</b> at 70 °C, leading to the coordinatively unsaturated products [Ru₂(ER₃)­(μ-H)­{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­(CO)₅] (ER₃ = SiEt₃, <b>9</b>; SnPh₃, <b>10</b>), which easily reacted with ^<i>t</i>BuNC and CO to give the saturated derivatives [Ru₂(ER₃)­(μ-H)­{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­(^<i>t</i>BuNC)­(CO)₅] (ER₃ = SiEt₃, <b>11</b>; SnPh₃, <b>12</b>) and [Ru₂(ER₃)­(μ-H)­{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­(CO)₆] (ER₃ = SiEt₃, <b>13</b>; SnPh₃, <b>14</b>), respectively. Compounds <b>9</b>–<b>14</b> have their ER₃ group on the Ru atom that is not attached to the amidinato fragment. In contrast, the reaction of <b>2</b> with H₂ at 70 °C led to the unsaturated tetranuclear complex [Ru₄(μ-H)₂{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}₂(CO)₁₀] (<b>15</b>), which also reacted with ^<i>t</i>BuNC and CO to give the saturated derivatives [Ru₄(μ-H)₂{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}₂(L)₂(CO)₁₀] (L = ^<i>t</i>BuNC, <b>16</b>; CO, <b>17</b>). All tetraruthenium complexes contain an unbridged metal–metal connecting two germylene-bridged diruthenium units. Under CO atmosphere, complex <b>17</b> reverted to compound <b>2</b>. All of the coordinatively unsaturated products (<b>9</b>, <b>10</b>, and <b>15</b>) have their unsaturation(s) located on the Ru atom(s) that is­(are) attached to the amidinato fragment(s). In the absence of added reagents, the thermolysis of <b>2</b> in refluxing toluene led to [Ru₄{μ–κ²<i>Ge,N-</i>Ge­(^<i>i</i>Pr₂bzam)­(HMDS)}­{μ₃−<i>κGe-</i>Ge­(HMDS)}­(μ–κ³<i>N,C,N</i>′<i>-</i>^<i>i</i>Pr₂bzam)­(μ-CO)­(CO)₈] (<b>18</b>), which contains two new ligands, a triply bridging germylidyne and a bridging benzamidinate, and that results from the condensation of two molecules of <b>2</b> and the activation of the Ge–N bond of the benzamidinatogermylene ligand of <b>2</b>