Ruthenaphosphaalkenyls: synthesis, structures, and their conversion to η2‑phosphaalkene complexes

The ruthenaphosphaalkenyls [Ru{PCH-(SiMe2R)}Cl(CO)(PPh3)2] (R = Me, Ph, Tol) have been prepared in good yield by the facile hydroruthenation of the respective phosphaalkynes, RMe2SiCP, with [RuHCl(CO)-(PPh3)3]; all three compounds have been structurally characterized in the solid state. Complemented by DFT studies of these, and the precedent [Ru{PCH(tBu)}Cl(CO)(PPh3)2], the phosphaalkenyl moieties have been established unequivocally to behave as one-electron donors to the coordinately unsaturated, 15-electron “RuCl(CO)(PPh3)2” fragment, corroborating an earlier demonstration of nucleophilic character at phosphorus within the tert-butyl system. Notwithstanding, the ruthenaphosphaalkenyls are shown to react with the nucelophiles Lipz′ (pz′ = pz, pz*, pzH,CF3, pzMe,CF3) to afford the η1,η2-chelated pyrazolylphosphaalkene complexes [Ru{η1-N:η2-P,C-P(pz′)CH(R)}(CO)(PPh3)2], which feature a three-membered metallacyclic (Ru−C−P) core. The nature of these novel compounds is discussed, alongside preliminary insight into the process by which they are formed

Synthesis and electronic structure of the first cyaphide-alkynyl complexes

The novel complexes trans-[Ru(dppe)2(CCR)(CP)] (R = CO2Me, C6H4OMe), the first to incorporate cyaphide as part of a conjugated system, are obtained in facile manner. The electronic structure of these compounds is probed by X-ray, DFT and UV/Vis studies

Hydrochlorination of ruthenaphosphaalkenyls: unexpectedly facile access to alkylchlorohydrophosphane complexes

The novel ruthenaphosphaalkenyls [Ru{P═C(H)SiMe2R}Cl- (CO)(PPh3)2] (R = p-C6H4CF3, nBu) have been prepared for the first time, and studied alongside precedent analogues (R = Me, Ph, p-tol) for their reactions with HCl. In contrast to chemistry defined for the tert-butyl congener [Ru{P═C(H)tBu}Cl(CO)(PPh3)2], which initially adds a single equivalent of HCl across the Ru−P linkage, all five silyl derivatives undergo spontaneous addition of a second equivalent to afford [Ru{η1-PHCl−CH2SiMe2R}Cl(CO)(PPh3)2], extremely rare examples of coordinated “PHXR” type ligands. Where R = SiMe3, a distorted octahedral geometry with a conformationally restricted “PHXR” ligand is observed crystallographically; this structure is appreciably retained in solution, as determined from multinuclear NMR spectroscopic features, which include a Karplus-like PPh3−Ru−P−H spin−spin coupling dependence. Computational data suggest a silyl-induced increase in negative charge density at the phosphaalkenic carbon, rather than an intrinsic thermodynamic driver, as the likely origin of the disparate reactivity

Large-Area Electrodeposition of Few-Layer MoS2 on Graphene for 2D Material Heterostructures

Heterostructures involving two-dimensional (2D) transition metal dichalcogenides and other materials such as graphene have a strong potential to be the fundamental building block of many electronic and opto-electronic applications. The integration and scalable fabrication of such heterostructures is of essence in unleashing the potential of these materials in new technologies. For the first time, we demonstrate the growth of few-layer MoS2 films on graphene via non-aqueous electrodeposition. Through methods such as scanning and transmission electron microscopy, atomic force microscopy, Raman spectroscopy, energy and wavelength dispersive X-ray spectroscopies and X-ray photoelectron spectroscopy, we show that this deposition method can produce large-area MoS2 films with high quality and uniformity over graphene. We reveal the potential of these heterostructures by measuring the photo-induced current through the film. These results pave the way towards developing the electrodeposition method for the large-scale growth of heterostructures consisting of varying 2D materials for many applications.Comment: 11 pages and 6 figure

?1:?2-P-pyrazolylphosphaalkene complexes of Ruthenium(0)

An extended range of novel ruthenium phosphaalkene complexes of the type[Ru{?1-N:?2-P,C-P(pz0)=CH(SiMe2R)}(CO)(PPh3)2] (R = Tol, C6H4CF3-p; pz0 = pzMe2, pzCF3, pzMe,CF3; R = Me, C6H4CF3-p; pz0 = pzPh) have been prepared from the respective ruthenaphosphaalkenyls [Ru{P=CH(SiMe2R)}Cl(CO)(PPh3)2] upon treatment with Lipz0. Where R = C6H4CF3-p and pz0 = pzMe2 the complex is characterized by single crystal X-ray diffraction, only the second example of such species being structurally characterized. This indicates enhanced pyramidalisation of the alkenic carbon center when compared with precedent data (R = Me, pz0 = pz) implying an enhanced Ru?p*PC contribution, which can be correlated with the greater donor power of pzMe2. This is similarly reflected in spectroscopic data that reveal significant influence of the pyrazolyl substituents upon the phosphaalkene, stronger donors imparting significantly enhanced shielding to phosphorus; in contrast, a much lesser influence if noted for the silyl substituents

Ambiphilic reactivity of a ruthenaphosphaalkenyl: synthesis of P-pyrazolylphosphaalkene complexes of ruthenium(0)

The novel ruthenaphosphaalkenyl complex [Ru{P═CH(SiMe3)}Cl(CO)(PPh3)2], prepared from [RuHCl(CO)(PPh3)3] and Me3SiC≡P, exhibits ambiphilic behavior, reacting at phosphorus with both nucleophiles and electrophiles. Its reaction with Li(pz′) or K[HB(pz′)3] (pz′ = pz, pz*) affords [Ru{η1-N:η2-P,C-P(pz′)═CH(SiMe3)}(CO)(PPh3)2], a rare example of a ruthenium(0) η2-phosphaalkene complex and the first example of a P-pyrazolylphosphaalkene. Conversely, reaction with the electrophilic PhHgCl leads to metalation at phosphorus, affording [Ru{η1-P(HgPh)═CH(SiMe3)}Cl2(CO)(PPh3)2]

Trialkylstibine Complexes of Boron, Aluminum, Gallium, and Indium Trihalides: Synthesis, Properties, and Bonding

The reaction of BX₃ (X = Cl, Br, I) with SbR₃ (R = Et,ⁱPr) in anhydrous hexane or toluene produced moisture-sensitive [BX₃(SbR₃)], whose stability increases with halide: Cl < Br < I. Unstable [BF₃(SbR₃)] species were also characterized spectroscopically but lose BF₃ very readily. The [MX₃(SbR₃)] (M = Al, Ga, In) complexes were isolated from hexane solution; the Ga and In complexes can be recrystallized unchanged from CH₂Cl₂, but [AlX′₃(SbR₃)] (X′ = Br, I) undergoes X′/Cl exchange with the solvent. The new complexes were characterized by IR and multinuclear NMR spectroscopy (¹H, ¹³C­{¹H}, ¹¹B, ²⁷Al, ⁷¹Ga, ¹¹⁵In, as appropriate). X-ray crystal structures are reported for [BX₃(SbR₃)] (X = Br, I; R = Et, ⁱPr; X = Cl, R = ⁱPr), [AlI₃(SbⁱPr₃)], [GaX₃(SbR₃)] (X = Cl, I; R = ⁱPr), [GaBr₃(SbEt₃)], and [InX₃(SbR₃)] (X = Cl, I; R = Et, ⁱPr); all contain pseudotetrahedral geometries at both the group 13 and antimony atoms, and comparisons with phosphine and arsine analogues are discussed. The donor–acceptor bond lengths are unexceptional, but coordination of the stibine is accompanied by a significant widening of the C–Sb–C angles and a small reduction in C–Sb distances. DFT calculations confirm these results from significant changes in the antimony 5s and 5p contributions to the Sb–C bonds, with corresponding increases in the 5p character of the antimony-based “lone pair” on coordination. Intermolecular hypervalent Cl···Sb interactions are present in the two [InCl₃(SbR₃)] complexes but absent in the others

Ruthenaphosphaalkenyls: Synthesis, Structures, and Their Conversion to η²‑Phosphaalkene Complexes

The ruthena­phospha­alkenyls [Ru­{PCH­(SiMe₂R)}­Cl­(CO)­(PPh₃)₂] (R = Me, Ph, Tol) have been prepared in good yield by the facile hydroruthenation of the respective phospha­alkynes, RMe₂SiCP, with [RuHCl­(CO)­(PPh₃)₃]; all three compounds have been structurally characterized in the solid state. Complemented by DFT studies of these, and the precedent [Ru­{PCH­(^<i>t</i>Bu)}­Cl­(CO)­(PPh₃)₂], the phospha­alkenyl moieties have been established unequivocally to behave as one-electron donors to the coordinately unsaturated, 15-electron “RuCl­(CO)­(PPh₃)₂” fragment, corroborating an earlier demonstration of nucleophilic character at phosphorus within the <i>tert-</i>butyl system. Notwithstanding, the ruthena­phospha­alkenyls are shown to react with the nucelophiles Lipz′ (pz′ = pz, pz*, pz^H,CF₃, pz^Me,CF₃) to afford the η¹,η²-chelated pyrazolyl­phospha­alkene complexes [Ru­{η¹-<i>N</i>:η²<i>-P,C-</i>P­(pz′)CH­(R)}­(CO)­(PPh₃)₂], which feature a three-membered metallacyclic (Ru–C–P) core. The nature of these novel compounds is discussed, alongside preliminary insight into the process by which they are formed

Trialkylstibine Complexes of Boron, Aluminum, Gallium, and Indium Trihalides: Synthesis, Properties, and Bonding

The reaction of BX₃ (X = Cl, Br, I) with SbR₃ (R = Et,ⁱPr) in anhydrous hexane or toluene produced moisture-sensitive [BX₃(SbR₃)], whose stability increases with halide: Cl < Br < I. Unstable [BF₃(SbR₃)] species were also characterized spectroscopically but lose BF₃ very readily. The [MX₃(SbR₃)] (M = Al, Ga, In) complexes were isolated from hexane solution; the Ga and In complexes can be recrystallized unchanged from CH₂Cl₂, but [AlX′₃(SbR₃)] (X′ = Br, I) undergoes X′/Cl exchange with the solvent. The new complexes were characterized by IR and multinuclear NMR spectroscopy (¹H, ¹³C­{¹H}, ¹¹B, ²⁷Al, ⁷¹Ga, ¹¹⁵In, as appropriate). X-ray crystal structures are reported for [BX₃(SbR₃)] (X = Br, I; R = Et, ⁱPr; X = Cl, R = ⁱPr), [AlI₃(SbⁱPr₃)], [GaX₃(SbR₃)] (X = Cl, I; R = ⁱPr), [GaBr₃(SbEt₃)], and [InX₃(SbR₃)] (X = Cl, I; R = Et, ⁱPr); all contain pseudotetrahedral geometries at both the group 13 and antimony atoms, and comparisons with phosphine and arsine analogues are discussed. The donor–acceptor bond lengths are unexceptional, but coordination of the stibine is accompanied by a significant widening of the C–Sb–C angles and a small reduction in C–Sb distances. DFT calculations confirm these results from significant changes in the antimony 5s and 5p contributions to the Sb–C bonds, with corresponding increases in the 5p character of the antimony-based “lone pair” on coordination. Intermolecular hypervalent Cl···Sb interactions are present in the two [InCl₃(SbR₃)] complexes but absent in the others