Organometallics最新文献

Reactions of RhH{κ³-P,O,P-[xant(PⁱPr₂)₂]} (xant(PⁱPr₂)₂ = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) with 2 equiv of tert-butylacetylene and phenylacetylene lead to the acetylide derivatives Rh(C≡CR){κ³-P,O,P-[xant(PⁱPr₂)₂]} (R = ^tBu, Ph). The C–C triple bond of these compounds undergoes the B–H anti-addition of pinacolborane (HBpin) to produce Rh{(E)-C(Bpin)=CHR-Pro-Z}{κ³-P,O,P-[xant(PⁱPr₂)₂]} (R = ^tBu, Ph), which regenerate Rh(C≡CR){κ³-P,O,P-[xant(PⁱPr₂)₂]} in the presence of a new alkyne molecule, releasing the respective (Z)-borylolefin. Complex Rh{(E)-C(Bpin)=CHPh-Pro-Z}{κ³-P,O,P-[xant(PⁱPr₂)₂]} is unstable in toluene. Initially, the C–C double bond of the borylalkenyl ligand undergoes a E to Z isomerization to produce Rh{(Z)-C(Bpin)═CHPh-Pro-E}{κ³-P,O,P-[xant(PⁱPr₂)₂]}, which subsequently evolves to the aryl derivative Rh{C₆H₄-2-[E-CH═CH(Bpin)]}{κ³-P,O,P-[xant(PⁱPr₂)₂]}. The latter reacts with a new phenylacetylene molecule to produce Rh(C≡CPh){κ³-P,O,P-[xant(PⁱPr₂)₂]} and the (E)-borylolefin. According to this reactivity, the complex RhH{κ³-P,O,P-[xant(PⁱPr₂)₂]} is an effective catalyst precursor for the hydroboration of terminal alkynes to mixtures of (Z)- and (E)-borylolefins. The molar ratio between isomers depends on the substituent of the alkyne; para-substituted aryl substituents with electron-withdrawing groups favor Z-borylolefin.

The direct construction of C–P bonds from white phosphorus (P₄) and nucleophilic reagents is of great scientific importance and application value. In this work, density functional theory calculations reveal the reaction mechanism of P₄ with the mono-lithium reagent, namely, 1,2,3,4-tetraethyl-1-lithiobuta-1,3-diene. The construction of C–P bonds is realized through the sequential nucleophilic attacks of the C–Li bond toward P₄ and P–P bonds toward the butadiene skeleton. The calculation results were confirmed by the model reaction of 1,2,3,4-tetraethyl-1-lithiobuta-1,3-diene with P₄ providing the corresponding phospholyl lithium selectively. This work combining computational prediction with experimental confirmation opens a new avenue for the discovery of the selective reaction between mono-lithium reagents and white phosphorus.

The dianion [Fe₂[(μ-SeCH₂)₂NH](CN)₂(CO)₄]^2– ([2]^2–) is of interest for the preparation of the selenide analog of the active site of the [FeFe]-hydrogenases. The obvious route for its synthesis by cyanation of Fe₂[(μ-SeCH₂)₂NH](CO)₆ (3) fails for reasons that this paper explains and resolves. We show that CN^– cleaves Se–C bonds in 3. For example, treatment of Fe₂[(μ-SeCH₂)₂NH](CO)₆ with NEt₄CN followed by CH₃I gives substantial amounts of Fe₂(μ-SeCH₃)₂(CO)₆. Authentic [2]^2– can be obtained by cyanation of Fe₂[(μ-SeCH₂)₂NH](CO)₅(pyridine). The ⁷⁷Se NMR data for [2]^2– and 3 are reevaluated and explained. Attempts to prepare Fe₂[(μ-SeCH₂)₂NH](PPh₃)₂(CO)₄ (9) by Me₃NO-induced decarbonylation of 3 also suffers from degradation of the organoselenium ligand. Complex 9 was prepared instead by photosubstitution. The protonation of [2]^2– and [Fe₂[(μ-SCH₂)₂NH](CN)₂(CO)₄]^2– are compared: the selenium compounds are more basic. The structure of [HFe₂[(μ-SCH₂)₂NH](CN)₂(CO)₄]⁻ was determined crystallographically.

Ruthenium complexes bearing a rationally designed tetradentate hemilabile ligand have been developed. The structures of the complexes and the hemilabile feature of the ligand have been disclosed by X-ray crystallography and NMR analyses. Moreover, in a ruthenium-catalyzed C(sp²)–H borylation of unactivated arenes, such a type of complex was found to show superior catalytic reactivity compared to tetradentate or tridentate phosphine ligands, which suggested that the hemilabile feature of the ligand is the key factor in promoting the reaction efficiently.

The dianion [Fe₂[(μ-SeCH₂)₂NH](CN)₂(CO)₄]^2- ([2]^2-) is of interest for the preparation of the selenide analog of the active site of the [FeFe]-hydrogenases. The obvious route for its synthesis by cyanation of Fe₂[(μ-SeCH₂)₂NH](CO)₆ (3) fails for reasons that this paper explains and resolves. We show that CN^- cleaves Se-C bonds in 3. For example, treatment of Fe₂[(μ-SeCH₂)₂NH](CO)₆ with NEt₄CN followed by CH₃I gives substantial amounts of Fe₂(μ-SeCH₃)₂(CO)₆. Authentic [2]^2- can be obtained by cyanation of Fe₂[(μ-SeCH₂)₂NH](CO)₅(pyridine). The ⁷⁷Se NMR data for [2]^2- and 3 are reevaluated and explained. Attempts to prepare Fe₂[(μ-SeCH₂)₂NH](PPh₃)₂(CO)₄ (9) by Me₃NO-induced decarbonylation of 3 also suffers from degradation of the organoselenium ligand. Complex 9 was prepared instead by photosubstitution. The protonation of [2]^2- and [Fe₂[(μ-SCH₂)₂NH](CN)₂(CO)₄]^2- are compared: the selenium compounds are more basic. The structure of [HFe₂[(μ-SCH₂)₂NH](CN)₂(CO)₄]^- was determined crystallographically.

Treatment of trivalent [K(18-crown-6)][U(I)₂{(Si(SiMe₃)₂SiMe₂)₂O}] (1-crown) with aryl diazenes generated a series of uranium(IV) species of the form [(THF)U(I)₂{N(R/R′)Si(SiMe₃)₂SiMe₂}₂O] (R = R′ = Ph (2-Ph), 4-FC₆H₄ (2-F), 4-MeC₆H₄ (2-Tol), 4-OMeC₆H₄ (2-Mes), and R = 4-MeC₆H₄, R′ = Ph (2-TolPh). Activation of an ortho-substituted diazene, (2,4,6-Me₃C₆H₂N)₂ (MesN═NMes), forms 2-Mes, [K(18-crown-6)][U(I)₃{N(Mes)Si(SiMe₃)₂SiMe₂}₂O] (2-MesKI), and ([K(18-crown-6][U(I)(NMes)(N[Mes]-3,3,5,5-Me₄2,2,6,6-(SiMe₃)₄-tetrasil-3-oxane)]) (3-Mes). The increased sterics of this ortho-substituted substrate slowed insertion, facilitating the observation of 3-Mes by in situ NMR spectroscopy. The redox potentials of the aryl diazenes (R–N═N–R′) were studied using cyclic voltammetry to elucidate their electronic contributions toward their reactivity with 1-crown. The reaction of 1-crown and (Z)-11,12-dihydrodibenzo[c,g][1,2]diazocine is also described, forming the [(THF)U(I)₂{[N(C₇H₆)]₂Si(SiMe₃)₂SiMe₂}₂O] (2-diazonine) and {(THF)₂U(I)₂[N(C₇H₆)]₂}₂ (4) dimers.

This study presents the synthesis of N-alkynylated acyclic diaminocarbene (ADC) complexes of palladium(II) and platinum(II) and their intramolecular cyclization via trans-chlorometalation. The reactions of propargylamines with bis-isocyanide complexes of Pd(II) and Pt(II) produced the desired ADC complexes in good yields. The NH,NH-diaminocarbene complexes were unstable in solution and underwent intramolecular cyclization into chlorometalated products. These findings provide a novel route to stable N-alkynylated ADC complexes with potential applications in catalysis and medicinal chemistry. The complexes synthesized exhibit promising structural and reactive properties suitable for further exploration.

We report the synthesis of two metal bis(amidophosphine selenide) complexes, ML₂ (M = Fe, Co; L = SePPh₂N⁽⁻⁾Tol), and investigate their reactivity toward ligand binding and oxidation with oxygen atom transfer reagents, pyridine-N-oxide and mesityl nitrile oxide. The oxidative strength of the reagent dictates the nature of the reactivity: either the ligand is oxidized, leading to the formation of a bimetallic mixed-ligand complex [MLL′]_n, (L′ = OPPh₂N⁽⁻⁾Tol), or the metal center is oxidized, resulting in a bimetallic μ-oxo complex [FeL₂]₂(μ₂-O). This study defines a chemical space in which amidophosphine selenide ligands maintain their structural integrity.

The catalytic system consisting of a cationic Ru–H complex 1 and 3,4,5,6-tetrachloro-1,2-benzoquinone (L1) was found to be highly effective for the dehydrative sp³ C–H coupling reaction of 2-alkyl substituted indoles with enones to form 2,4-disubstituted carbazole products. The analogous coupling reaction of 2-alkylindoles with linear enones bearing the cyclic olefinic group afforded tetracyclic carbazole products. A normal deuterium kinetic isotope effect was measured from the coupling reaction of 1,2-dimethylindole versus 1-methyl-2-(methyl-d₃)indole with (E)-3-penten-2-one (k_H/k_D = 2.5). The Hammett plot was constructed from the reaction of para-substituted indoles 5-X-1,2-dimethylindole (X = OMe, Me, H, F, and Cl) with 4-phenyl-3-buten-2-one (ρ = −1.6 ± 0.2). The density functional theory (DFT) calculations were performed to obtain a complete energy profile for the coupling reaction. The combined experimental and DFT computational data revealed a detailed mechanistic path that features an initial coupling of indole and enone substrates, the turnover-limiting heterolytic sp³ C–H activation step, and the subsequent cyclization and dehydration steps. The catalytic method provides an efficient synthesis of carbazole derivatives from the dehydrative sp³ C–H coupling reaction of readily available indole with enone substrates without employing any reactive reagents or forming wasteful byproducts.