Gioventù bruciata? La condizione giovanile e la sfida del social investment

At the basis of the Europe 2020 strategy there is the confidence that post-industrial societies have a stronger need of qualified workers and that this will reinforce the economic sustainability of the European social model. Not unsurprisingly given the unfavourable context, from the perspective of social investment strategy Italy is a worst practice in Europe. Young generations in Italy are extremely less copious than any older generation (especially confronted with other European countries), but despite their low numbers their labour market indicators are worst. Some scholars actually doubt that Italy will effectively benefit from the improved human capital of new generations, thus putting under investigation of the principle of social investment

Molybdenum Hydride and Dihydride Complexes Bearing Diphosphine Ligands with a Pendant Amine: Formation of Complexes with Bound Amines

CpMo­(CO)­(PNP)H complexes (PNP = (R₂PCH₂)₂NMe, R = Et or Ph) were synthesized by displacement of two CO ligands of CpMo­(CO)₃H by the PNP ligand; these complexes were characterized by IR and variable temperature ¹H and ³¹P NMR spectroscopy. CpMo­(CO)­(PNP)­H complexes are formed as mixture of <i>cis</i>- and <i>trans</i>-isomers. The structures of both <i>cis-</i>CpMo­(CO)­(P^EtN^MeP^Et)H and <i>trans-</i>CpMo­(CO)­(P^PhN^MeP^Ph)H were determined by single crystal X-ray diffraction. Electrochemical oxidation of CpMo­(CO)­(P^EtN^MeP^Et)­H and CpMo­(CO)­(P^PhN^MeP^Ph)H in CH₃CN are both irreversible at slow scan rates and quasireversible at higher scan rates, with <i>E</i>_1/2 = −0.36 V (vs Cp₂Fe^+/0) for CpMo­(CO)­(P^EtN^MeP^Et)H and <i>E</i>_1/2 = −0.18 V for CpMo­(CO)­(P^PhN^MeP^Ph)­H. Hydride abstraction from CpMo­(CO)­(PNP)H with [Ph₃C]⁺[A]⁻ (A = B­(C₆F₅)₄ or BAr^F₄; [Ar^F = 3,5-bis­(trifluoromethyl)­phenyl]) afforded “tuck-in” [CpMo­(CO)­(κ³-PNP)]⁺ complexes that feature the amine bound to the metal. Displacement of the κ³ Mo–N bond by CD₃CN gives [CpMo­(CO)­(PNP)­(CD₃CN)]⁺. The kinetics of this reaction were studied by ³¹P­{¹H} NMR spectroscopy for [CpMo­(CO)­(κ³-P^EtN^MeP^Et)]⁺, providing the activation parameters Δ<i>H</i>^⧧ = 21.6 ± 2.8 kcal/mol, Δ<i>S</i>^⧧ = −0.3 ± 9.8 cal/(mol K), <i>E</i>_a = 22.1 ± 2.8 kcal/mol. Protonation of CpMo­(CO)­(P^EtN^MeP^Et)H affords the Mo dihydride complex [CpMo­(CO)­(κ²-P^EtN^MeP^Et)­(H)₂]⁺, which loses H₂ to generate [CpMo­(CO)­(κ³-P^EtN^MeP^Et)]⁺ at room temperature. Our results show that the pendant amine has a strong driving force to form stable “tuck-in” [CpMo­(CO)­(κ³-PNP)]⁺ complexes, and also promotes hydrogen elimination from [CpMo­(CO)­(PNP)­(H)₂]⁺ complexes by formation of a Mo–N dative bond. CpMo­(CO)­(dppp)H (dppp = 1,3-bis­(diphenylphosphino)­propane) was studied as a Mo diphosphine analogue without a pendant amine, and the product of protonation of this complex gives [CpMo­(CO)­(dppp)­(H)₂]⁺

Molybdenum Hydride and Dihydride Complexes Bearing Diphosphine Ligands with a Pendant Amine: Formation of Complexes with Bound Amines

CpMo­(CO)­(PNP)H complexes (PNP = (R₂PCH₂)₂NMe, R = Et or Ph) were synthesized by displacement of two CO ligands of CpMo­(CO)₃H by the PNP ligand; these complexes were characterized by IR and variable temperature ¹H and ³¹P NMR spectroscopy. CpMo­(CO)­(PNP)­H complexes are formed as mixture of <i>cis</i>- and <i>trans</i>-isomers. The structures of both <i>cis-</i>CpMo­(CO)­(P^EtN^MeP^Et)H and <i>trans-</i>CpMo­(CO)­(P^PhN^MeP^Ph)H were determined by single crystal X-ray diffraction. Electrochemical oxidation of CpMo­(CO)­(P^EtN^MeP^Et)­H and CpMo­(CO)­(P^PhN^MeP^Ph)H in CH₃CN are both irreversible at slow scan rates and quasireversible at higher scan rates, with <i>E</i>_1/2 = −0.36 V (vs Cp₂Fe^+/0) for CpMo­(CO)­(P^EtN^MeP^Et)H and <i>E</i>_1/2 = −0.18 V for CpMo­(CO)­(P^PhN^MeP^Ph)­H. Hydride abstraction from CpMo­(CO)­(PNP)H with [Ph₃C]⁺[A]⁻ (A = B­(C₆F₅)₄ or BAr^F₄; [Ar^F = 3,5-bis­(trifluoromethyl)­phenyl]) afforded “tuck-in” [CpMo­(CO)­(κ³-PNP)]⁺ complexes that feature the amine bound to the metal. Displacement of the κ³ Mo–N bond by CD₃CN gives [CpMo­(CO)­(PNP)­(CD₃CN)]⁺. The kinetics of this reaction were studied by ³¹P­{¹H} NMR spectroscopy for [CpMo­(CO)­(κ³-P^EtN^MeP^Et)]⁺, providing the activation parameters Δ<i>H</i>^⧧ = 21.6 ± 2.8 kcal/mol, Δ<i>S</i>^⧧ = −0.3 ± 9.8 cal/(mol K), <i>E</i>_a = 22.1 ± 2.8 kcal/mol. Protonation of CpMo­(CO)­(P^EtN^MeP^Et)H affords the Mo dihydride complex [CpMo­(CO)­(κ²-P^EtN^MeP^Et)­(H)₂]⁺, which loses H₂ to generate [CpMo­(CO)­(κ³-P^EtN^MeP^Et)]⁺ at room temperature. Our results show that the pendant amine has a strong driving force to form stable “tuck-in” [CpMo­(CO)­(κ³-PNP)]⁺ complexes, and also promotes hydrogen elimination from [CpMo­(CO)­(PNP)­(H)₂]⁺ complexes by formation of a Mo–N dative bond. CpMo­(CO)­(dppp)H (dppp = 1,3-bis­(diphenylphosphino)­propane) was studied as a Mo diphosphine analogue without a pendant amine, and the product of protonation of this complex gives [CpMo­(CO)­(dppp)­(H)₂]⁺

Palladium-Catalyzed Synthesis of Benzosilolo[2,3-<i>b</i>]indoles via Cleavage of a C(sp³)–Si Bond and Consequent Intramolecular C(sp²)–Si Coupling

An efficient process involving Pd-catalyzed selective cleavage of a C(sp3)–Si bond and consequent intramolecular C(sp2)–Si coupling has been developed, affording benzosilolo[2,3-b]indoles as a new type of silicon-bridged polyheteroarene in excellent yields. Aldehyde was found for the first time to be able to promote the efficiency of the catalytic process remarkably

Palladium-Catalyzed Synthesis of Benzosilolo[2,3-<i>b</i>]indoles via Cleavage of a C(sp³)–Si Bond and Consequent Intramolecular C(sp²)–Si Coupling

An efficient process involving Pd-catalyzed selective cleavage of a C(sp3)–Si bond and consequent intramolecular C(sp2)–Si coupling has been developed, affording benzosilolo[2,3-b]indoles as a new type of silicon-bridged polyheteroarene in excellent yields. Aldehyde was found for the first time to be able to promote the efficiency of the catalytic process remarkably

One-Pot Synthesis of Pyrrolo[3,2-<i>d</i>]pyridazines and Pyrrole-2,3-diones via Zirconocene-Mediated Four-Component Coupling of Si-Tethered Diyne, Nitriles, and Azide

A one-pot synthesis of pyrrolo[3,2-d]pyridazine derivatives via zirconocene-mediated four-component coupling of one Si-tethered diyne, two nitriles, and one azide is reported. When TMSN3 was used, pyrrole-2,3-diones were formed in good yields. Further condensation of these highly functionalized pyrrole-2,3-diones with hydrazine and hydroxylamine afforded useful pyrrole-fused heterocycles

Formation of Zirconocenes Containing Vinyl-imine and Keteniminate Species from Zirconacycles and Diphenylacetonitrile

The first well-defined zirconocene complexes processing vinyl-imine and keteniminate species have been achieved from zirconacyclopentenes or zirconacyclopentadienes and 2 equiv of Ph2CHCN. Multifunctional effect of Ph2CHCN is observed for the first time in one system. This process proceeds via the azazirconacyclopentadiene intermediate and its intramolecular proton transfer. Moreover, β,β′-C–C bond cleavage of tetra-alkyl-substituted zirconacyclopentadienes is observed for the first time under the appropriate conditions

Cleavage and Reorganization of Zr−C/Si−C Bonds Leading to Zr/Si−N Organometallic and Heterocyclic Compounds

The t-BuCN-stabilized zirconacyclopropene−azasilacyclopentadiene complexes 2 are generated in situ in high yields from the Si-tethered diynes, Cp2Zr(II) species, and 2 equiv of t-BuCN via a coordination-induced Zr−C/Si−C bond cleavage and reorganization. Complexes 2 have been demonstrated to be synthetically very useful. A variety of novel Zr/Si organo-bimetallic compounds and Si/N heterocyclic compounds, such as azasilacyclopentadienes, azasilacyclohexadienes, and allenylazazirconacycles, are obtained in high yields when complexes 2 are treated with ketones, carbodiimides, alkynes, elemental sulfur (S8), acid chlorides, or nitriles. In this chemistry, t-BuCN behaves as both an initiator and a brake/release handle to initiate and control the reaction process

Reactivity of Seven-Membered Azazirconacycloallenes and Four-Membered Zirconacycles toward Diphenylacetonitrile

The reaction of the seven-membered azazirconacycloallene 2 with Ph2CHCN was carried out to yield a zirconocene complex with three fused rings and a keteniminate ligand. Further reactivity toward propargyl bromide or propionyl chloride shows that the keteniminate ligand can be replaced by halogen atoms (Br or Cl). In addition, the reaction of the strained four-membered zirconacycle 1 with Ph2CHCN gives zirconocenes possessing vinyl-imine and keteniminate species

Cleavage and Reorganization of Zr−C/Si−C Bonds Leading to Zr/Si−N Organometallic and Heterocyclic Compounds

The t-BuCN-stabilized zirconacyclopropene−azasilacyclopentadiene complexes 2 are generated in situ in high yields from the Si-tethered diynes, Cp2Zr(II) species, and 2 equiv of t-BuCN via a coordination-induced Zr−C/Si−C bond cleavage and reorganization. Complexes 2 have been demonstrated to be synthetically very useful. A variety of novel Zr/Si organo-bimetallic compounds and Si/N heterocyclic compounds, such as azasilacyclopentadienes, azasilacyclohexadienes, and allenylazazirconacycles, are obtained in high yields when complexes 2 are treated with ketones, carbodiimides, alkynes, elemental sulfur (S8), acid chlorides, or nitriles. In this chemistry, t-BuCN behaves as both an initiator and a brake/release handle to initiate and control the reaction process