Amide-Templated Iodoplumbates: Extending Lead-Iodide Based Hybrid Semiconductors

Lead iodide–organic hybrids (iodoplumbates) have emerged as a class of materials with promising electronic and optical properties, and potential applications in photovoltaics and electronic devices. Hybrid iodoplumbates are composed of organic cations and lead iodide anions that exhibit diverse morphologies which determine the optical and electronic properties of the crystal. However, the diversity of the iodoplumbates is limited by the types of organic cations amenable for integration into the structure. Amides represent one of the largest groups of organic molecules, yet no examples of iodoplumbates based on protonated amide cations have been demonstrated so far. In this work, we show that it is possible to consistently grow iodoplumbates from amides following two distinct pathways. The first pathway involves growing iodoplumbates using amidium (protonated amides) as the organic cation in the crystal, which occurs for tertiary amides and urea. The second pathway involves growing iodoplumbates from primary and secondary amides, resulting in crystals containing the ammonium hydrolysis product of the amide. This path also leads to an interesting case of ring opening crystallization. The lead iodide one-dimensional chain motif composes most of the resulting structures. The large number of available amide molecules suggests that this method considerably expands the range of possible iodoplumbate structures

Amide-Templated Iodoplumbates: Extending Lead-Iodide Based Hybrid Semiconductors

Lead iodide–organic hybrids (iodoplumbates) have emerged as a class of materials with promising electronic and optical properties, and potential applications in photovoltaics and electronic devices. Hybrid iodoplumbates are composed of organic cations and lead iodide anions that exhibit diverse morphologies which determine the optical and electronic properties of the crystal. However, the diversity of the iodoplumbates is limited by the types of organic cations amenable for integration into the structure. Amides represent one of the largest groups of organic molecules, yet no examples of iodoplumbates based on protonated amide cations have been demonstrated so far. In this work, we show that it is possible to consistently grow iodoplumbates from amides following two distinct pathways. The first pathway involves growing iodoplumbates using amidium (protonated amides) as the organic cation in the crystal, which occurs for tertiary amides and urea. The second pathway involves growing iodoplumbates from primary and secondary amides, resulting in crystals containing the ammonium hydrolysis product of the amide. This path also leads to an interesting case of ring opening crystallization. The lead iodide one-dimensional chain motif composes most of the resulting structures. The large number of available amide molecules suggests that this method considerably expands the range of possible iodoplumbate structures

Actinide Complexes Possessing Six-Membered N‑Heterocyclic Iminato Moieties: Synthesis and Reactivity

A novel class of ligand systems possessing a six-membered N-heterocyclic iminato [perimidin-2-iminato (Pr^RN, where R = isopropyl, cycloheptyl)] moiety is introduced. The complexation of these ligands with early actinides (An = Th and U) results in powerful catalysts [(Pr^RN)­An­(N­{SiMe₃)₂}₃] (<b>3</b>–<b>6</b>) for exigent insertion of alcohols into carbodiimides to produce the corresponding isoureas in short reaction times with excellent yields. Experimental, thermodynamic, and kinetic data as well as the results of stoichiometric reactions provide cumulative evidence that supports a plausible mechanism for the reaction

Synthesis of Coordinatively Unsaturated Tetravalent Actinide Complexes with η⁵ Coordination of Pyrrole

The synthesis of new actinide complexes utilizing bridged α-alkyl-pyrrolyl ligands is presented. Lithiation of the ligands followed by treatment with 1 equiv of actinide tetrachloride (uranium or thorium) produces the desired complex in good yield. X-ray diffraction studies reveal unique η⁵:η⁵ coordination of the pyrrolyl moieties; when the nonsterically demanding methylated ligand is used, rapid addition of the lithiated ligand solution to the metal precursor forms a bis-ligated complex that reveals η⁵:η¹ coordination as determined by crystallographic analysis

Nitrogen Lewis Acids

Being a major conception of chemistry, Lewis acids have found countless applications throughout chemical enterprise. Although many chemical elements can serve as the central atom of Lewis acids, nitrogen is usually associated with Lewis bases. Here, we report on the first example of robust and modifiable Lewis acids centered on the nitrogen atom, which provide stable and well-characterized adducts with various Lewis bases. On the basis of the reactivity of nitrogen Lewis acids, we prepared, for the first time, cyclic triazanes, a class of cyclic organic compounds sequentially bearing three all-saturated nitrogen atoms (N–N–N motif). Reactivity abilities of these <i>N</i>-Lewis acids were explained by theoretical calculations. Properties and future applications of nitrogen Lewis acids are intriguing

Actinide Amidinate Complexes with a Dimethylamine Side Arm: Synthesis, Structural Characterization, and Reactivity

The reactivity of monoanionic amidinate ligands containing a dimethylamine side arm with variable lengths of the linker chain and aromatic substituents of the ipso carbon atom was investigated for the early actinides thorium and uranium. The bis­(amidinate) actinide complexes obtained were structurally characterized, displaying a coordination of both dimethylamine nitrogen atoms to the respective metal center, allowing for a fine tuning of the reactivity of the complex by manipulation of the coordination environment around the metal center. The reactivity of the actinide amidinate complexes was studied in the catalytic ring-opening polymerization of ε-caprolactone

Addition of E–H (E = N, P, C, O, S) Bonds to Heterocumulenes Catalyzed by Benzimidazolin-2-iminato Actinide Complexes

The synthesis and characterization of benzimidazolin-2-iminato actinide­(IV) complexes [(Bim^R1/R2N)­An­(N­{SiMe₃}₂)₃] (An = U, Th) (<b>1</b>–<b>6</b>) is reported. All complexes were obtained in high yields, and their solid state structures were established through single-crystal X-ray diffraction analysis. Using <b>1</b>–<b>6</b> as precatalysts, the addition of mono- and bifunctional E–H (E = N, P, C, O, S) substrates to various heterocumulenes, including carbodiimides, isocyanates, and isothiocyanates, was investigated, affording the respective addition products in high yields under very mild reaction conditions. Various amines were applicable to this reaction, indicating a large scope capability of amine nucleophiles for the insertion process

Catalytic Addition of Alcohols to Carbodiimides Mediated by Benzimidazolin-2-iminato Actinide Complexes

The synthesis of methyl and methoxy substituted benzimidazolin-2-iminato actinide (IV) complexes (<b>1</b>–<b>4</b>), [(Bim^2‑MeOPh/MeN)­AnN″₃] and [(Bim_5‑Me^Dipp/MeN)­AnN″₃] (An = U, Th; N″ = N­(SiMe₃)₂), was performed by the protonolysis of the actinide metallacycles with the respective neutral benzimidazolin-2-imine ligand precursors. Full characterization, including X-ray diffraction studies for all the complexes, is reported. Despite the high oxophilicity of the actinide metal centers, these complexes displayed extremely high activities in the catalytic addition of aliphatic and aromatic alcohols to carbodiimides, under very mild conditions, providing a facile and highly efficient strategy for the construction of carbon–oxygen bonds. Various kinds of diols and triols can also be used in this intermolecular insertion, representing a large substrate scope for the application of these organoactinide precatalysts

Mono(imidazolin-2-iminato) Actinide Complexes: Synthesis and Application in the Catalytic Dimerization of Aldehydes

The synthesis of the mono­(imidazolin-2-iminato) actinide­(IV) complexes [(Im^RN)­An­(N­{SiMe₃)₂}₃] (<b>3</b>–<b>8</b>) was accomplished by the protonolysis reaction between the respective imidazolin-2-imine (Im^RNH, R = <i>t</i>Bu, Mes, Dipp) and the actinide metallacycles [{(Me₃Si)­N}₂An­{κ²<i>C</i>,<i>N</i>-CH₂SiMe₂N­(SiMe₃)}] (<b>1</b>, An = U; <b>2</b>, M = Th). The thorium and uranium complexes were obtained in high yields, and their structures were established by single-crystal X-ray diffraction analysis. The mono­(imidazolin-2-iminato) actinide complexes <b>3</b>–<b>8</b> display short An–N bonds together with large An–N–C angles, indicating strong electron donation from the imidazolin-2-iminato moiety to the metal, corroborating a substantial π-character to the An–N bond. The reactivity of complexes <b>3</b>–<b>8</b> toward benzaldehyde was studied in the catalytic dimerization of aldehydes (Tishchenko reaction), displaying low to moderate catalytic activities for the uranium complexes <b>3</b>–<b>5</b> and moderate to high catalytic activities for the thorium analogues <b>6</b>–<b>8</b>, among which <b>8</b> exhibited the highest catalytic activity. In addition, actinide coordination compounds showed unprecedented reactivity toward cyclic and branched aliphatic aldehydes in the catalytic Tishchenko reaction mediated by the thorium complex [(Im^DippN)­Th­{N­(SiMe₃)₂}₃] (<b>8</b>), exhibiting high activity even at room temperature. Moreover, complex <b>8</b> was successfully applied in the crossed Tishchenko reaction between an aromatic or polyaromatic and an aliphatic cyclic and branched aldehyde, yielding selectively the asymmetrically substituted ester in high yields (80–100%)

Surprising Route to a Monoazaporphyrin and Full Characterization of Its Complexes with Five Different 3d Metals

In the search for mild agents for the oxidative cyclization of tetrapyrromethane to the corresponding corrole, we discovered a route that leads to a monoazaporphyrin with three meso-CF3 groups. Optimization studies that allowed access to appreciable amounts of this new macrocycle paved the way for the preparation of its cobalt, copper, nickel, zinc, and iron complexes. All complexes were fully characterized by various spectroscopic methods and X-ray crystallography. Their photophysical and electrochemical properties were determined and compared to those of analogous porphyrins in order to deduce the effect of the peripheral N atom. Considering the global efforts for designing efficient alternatives to platinum group metal (PGM) catalysts, they were also absorbed onto a porous carbon electrode material and studied as electrocatalysts for the oxygen reduction reaction (ORR). The cobalt complex was found to be operative at a quite positive catalytic onset potential and with good selectivity for the desirable 4-electrons/4-protons pathway