Highly Efficient Generation of Hydrogen from the Hydrolysis of Silanes Catalyzed by [RhCl(CO)₂]₂

Catalytic hydrolysis of silanes mediated by chlorodicarbonylrhodium­(I) dimer [RhCl­(CO)₂]₂ to produce silanols and dihydrogen efficiently under mild conditions is reported. Second-order kinetics and activation parameters are determined by monitoring the rate of dihydrogen evolution. The mixing of [RhCl­(CO)₂]₂ and HSiCl₃ results in rapid formation of a rhodium silane σ complex

Visible-Light-Promoted Generation of Hydrogen from the Hydrolysis of Silanes Catalyzed by Rhodium(III) Porphyrins

Visible-light-promoted hydrolysis of silanes catalyzed by (TAP)­Rh–I to produce silanols and dihydrogen efficiently under mild conditions was reported. (TAP)­Rh–H was observed as the key intermediate through stoichiometric activation of the Si–H bond by (TAP)­Rh–I. Addition of water drove the stoichiometric activation of Si–H into catalysis

The Mechanism of E–H (E = N, O) Bond Activation by a Germanium Corrole Complex: A Combined Experimental and Computational Study

(TPFC)­Ge­(TEMPO) (<b>1</b>, TPFC = tris­(pentafluorophenyl)­corrole, TEMPO^• = (2,2,6,6-tetramethylpiperidin-1-yl)­oxyl) shows high reactivity toward E–H (E = N, O) bond cleavage in R₁R₂NH (R₁R₂ = HH, ^<i>n</i>PrH, ^<i>i</i>Pr₂, Et₂, PhH) and ROH (R = H, CH₃) under visible light irradiation. Electron paramagnetic resonance (EPR) analyses together with the density functional theory (DFT) calculations reveal the E–H bond activation by [(TPFC)­Ge]⁰(<b>2</b>)/TEMPO^• radical pair, generated by photocleavage of the labile Ge–O bond in compound <b>1</b>, involving two sequential steps: (i) coordination of substrates to [(TPFC)­Ge]⁰ and (ii) E–H bond cleavage induced by TEMPO^• through proton coupled electron transfer (PCET)

Synthesis, Electronic Structure, and Reactivity Studies of a 4‑Coordinate Square Planar Germanium(IV) Cation

A tetra-coordinate, square planar germanium­(IV) cation [(TPFC)­Ge]⁺ (TPFC = tris­(pentafluorophenyl)­corrole) was synthesized quantitatively by the reaction of (TPFC)­Ge–H with [Ph₃C]⁺[B­(C₆F₅)₄]^¯. The highly reactive [(TPFC)­Ge]⁺ cation reacted with benzene to form phenyl complex (TPFC)­Ge–C₆H₅ through an electrophilic pathway. The key intermediate, a σ-type germylium-benzene adduct, [(TPFC)­Ge­(η¹-C₆H₆)]⁺, was isolated and characterized by single-crystal X-ray diffraction. Deprotonation of [(TPFC)­Ge­(η¹-C₆H₆)]⁺ cation led to the formation of (TPFC)­Ge–C₆H₅. [(TPFC)­Ge]⁺ also reacted with ethylene and cyclopropane in benzene at room temperature to form (TPFC)­Ge–CH₂CH₂C₆H₅ and (TPFC)­Ge–CH₂CH₂CH₂C₆H₅, respectively. The observed electrophilic reactivity is ascribed to the highly exposed cationic germanium center with novel frontier orbitals comprising two vacant sp-hybridized orbitals that are not conjugated to π-system. The three electron-withdrawing pentafluorophenyl groups on the corrole ligand also enhance the electrophilicity of the cationic germanium corrole

Exploring Polymorphism: Hydrochloride Salts of Pitolisant and Analogues

Pitolisant hydrochloride is used to treat excessive daytime sleepiness in adults with narcolepsy. The drug is formulated as a crystalline solid, and a monoclinic P21 form has been claimed in patents, but little additional information about the structure and polymorphism of the compound has been published. No new forms were obtained when we grew crystals from solution under various conditions. Re-examination of the crystals revealed a disordered and partially hydrated structure that resembles the one reported earlier but is not identical. Further insight was obtained by synthesizing analogues of pitolisant with its Cl substituent replaced by Me, F, and Br, followed by structural analysis of the hydrochloride salts by X-ray diffraction. Pitolisant hydrochloride and its three analogues showed very similar solid-state behavior, and each compound yielded new metastable forms when crystallized from melts. The lifetime of metastable form III of pitolisant hydrochloride could be extended significantly by adding small amounts of the fluoro analogue, but none of the metastable forms could be obtained as single crystals suitable for structural analysis. Computational predictions of the polymorphic landscapes of pitolisant hydrochloride and its analogues identified possible structures of the metastable forms. Dual experimental and computational approaches are already widely used in polymorphic screening, but our work shows the value of broadening these searches to include sets of structural analogues