Tweaking the Charge Transfer: Bonding Analysis of Bismuth(III) Complexes with a Flexidentate Phosphane Ligand

To account for the charge transfer and covalent character in bonding between P and Bi centers, the electronic structures of [P(C6H4-o-CH2SCH3)3BiCln](3–n)+ (n = 0–3) model species have been investigated computationally. On the basis of this survey a synthetic target compound with a dative P→Bi bond has been selected. Consecutively, the highly reactive bismuth cage [P(C6H4-o-CH2SCH3)3Bi]3+ has been accessed experimentally and characterized. Importantly, our experiments (single-crystal X-ray diffraction and solid-state NMR spectroscopy) and computations (NBO and AIM analysis) reveal that the P···Bi bonding in this trication can be described as a dative bond. Here we have shown that our accordion-like molecular framework allows for tuning of the interaction between P and Bi centers

Iron Sulfide Materials: Catalysts for Electrochemical Hydrogen Evolution

The chemical challenge of economically splitting water into molecular hydrogen and oxygen requires continuous development of more efficient, less-toxic, and cheaper catalyst materials. This review article highlights the potential of iron sulfide-based nanomaterials as electrocatalysts for water-splitting and predominantly as catalysts for the hydrogen evolution reaction (HER). Besides new synthetic techniques leading to phase-pure iron sulfide nano objects and thin-films, the article reviews three new material classes: (a) FeS2-TiO2 hybrid structures; (b) iron sulfide-2D carbon support composites; and (c) metal-doped (e.g., cobalt and nickel) iron sulfide materials. In recent years, immense progress has been made in the development of these materials, which exhibit enormous potential as hydrogen evolution catalysts and may represent a genuine alternative to more traditional, noble metal-based catalysts. First developments in this comparably new research area are summarized in this article and discussed together with theoretical studies on hydrogen evolution reactions involving iron sulfide electrocatalysts

Phosphaketenes as Building Blocks for the Synthesis of Triphospha Heterocycles

Unsaturated phosphorus compounds, such as phosphaalkenes and phosphaalkynes, show a versatile reactivity in cycloadditions. Although phosphaketenes (R-P=C=O) have been known for three decades, their chemistry has remained limited. Herein, we show that heteroatom-substituted phosphaketenes, R(3) E-P=C=O (E=Si, Sn), are building blocks for silyl- and stannyl-substituted five-membered heterocycles containing three phosphorous atoms. The structure of the heterocyclic anion depends on the nature of the tetrel atom involved. Although the silyl analogue [P(3)C(2) (OSiR(3))(2)](-) is an aromatic 1,2,4-triphospholide, the stannyl compound [P(CO)(2) (PSnR(3))(2)](-) is a 1,2,4-triphosphacyclopenta-3,5-dionate with a delocalized OCPCO fragment. Because of their anionic character, these compounds can easily be used as building blocks, for example, in the preparation of a silyl-functionalized hexaphosphaferrocene or the parent 1,2,4-triphosphacyclopenta-3,5-dionate [P(CO)(2) (PH)(2)](-). NMR spectroscopic investigations and computations have shown that the heterocycle-formation reactions presented herein are remarkably complex

Dibismuthates as Linking Units for Bis-Zwitterions and Coordination Polymers

Adducts of bismuth trihalides BiX3 (X = Cl, Br, I) and the PS3 ligand (PS3 = P(C6H4-o-CH2SCH3)3) react with HCl to form inorganic/organic hybrids with the general formula [HPS3BiX4]2. On the basis of their solid-state structures determined by single-crystal X-ray diffraction, these compounds exhibit discrete bis-zwitterionic assemblies consisting of two phosphonium units [HPS3]+ linked to a central dibismuthate core [Bi2X8]2– via S→Bi dative interactions. Remarkably, the phosphorus center of the PS3 ligand undergoes protonation with hydrochloric acid. This is in stark contrast to the protonation of phosphines commonly observed with hydrogen halides resulting in equilibrium. To understand the important factors in this protonation reaction, 31P NMR experiments and DFT computations have been performed. Furthermore, the dibismuthate linker was utilized to obtain the coordination polymer {[AgPS3BiCl3(OTf)]2(CH3CN)2}∞, in which dicationic [Ag(PS3)]22+ macrocycles containing five-coordinate silver centers connect the dianionic [Bi2Cl6(OTf)2]2– dibismuthate fragments. The bonding situation in these dibismuthates has been investigated by single-crystal X-ray diffraction and DFT calculations (NBO analysis, AIM analysis, charge distribution)

The reactivity of acyl chlorides towards sodium phosphaethynolate, Na(OCP): a mechanistic case study

The reaction of Na(OCP) with mesitoyl chloride delivers an ester functionalized 1,2,4-oxadiphosphole in a clean and P-atom economic way. The reaction mechanism has been elucidated by means of detailed NMR-spectroscopic, kinetic and computational studies. The initially formed acyl phosphaketene undergoes a pseudo-coarctate cyclization with an (OCP)− anion under the loss of carbon monoxide to yield a five-membered ring anion. Subsequently, the nucleophilic attack of the formed heterocyclic anion on a second acyl chloride molecule results in the 1,2,4-oxadiphosphole. The transient acyl phosphaketene is conserved during the reaction in the form of four-membered ring adducts, which act as a reservoir. Consequently, the phosphaethynolate anion has three different functions in these reactions: it acts as a nucleophile, as an en-component in [2 + 2] cycloadditions and as a formal P− transfer reagent

Weak pnictogen bond with bismuth: Experimental evidence based on Bi-P through-space coupling

To study pnictogen bonding involving bismuth, flexible accordion‐like molecular complexes of the composition [P(C6H4‐o‐CH2SCH3)3BiX3], (X=Cl, Br, I) have been synthesised and characterised. The strength of the weak and mainly electrostatic interaction between the Bi and P centres strongly depends on the character of the halogen substituent on bismuth, which is confirmed by single‐crystal X‐ray diffraction analyses, DFT and ab initio computations. Significantly, 209Bi–31P through‐space coupling (J=2560 Hz) is observed in solid‐state 31P NMR spectra, which is so far unprecedented in the literature, delivering direct information on the magnitude of this pnictogen interaction