Synthesis, Characterization, and Reactivity Studies of Subphthalocyanine Boron Triflate

The highly reactive subphthalocyanine boron triflate complex ((subPc)­BOTf) was isolated and characterized by X-ray diffraction and spectroscopic methods. The combination of (subPc)­BOTf and bis­(trimethyl­silyl)­amide (LiHMDS) yielded a “kinetically induced” frustrated Lewis pair system capable of activating a variety of substrates such as ethers, amides, and ketones. These reactions demonstrate the high reactivity of (subPc)­BOTf toward organic molecules

Synthesis, Characterization, and Reactivity Studies of Subphthalocyanine Boron Triflate

The highly reactive subphthalocyanine boron triflate complex ((subPc)­BOTf) was isolated and characterized by X-ray diffraction and spectroscopic methods. The combination of (subPc)­BOTf and bis­(trimethyl­silyl)­amide (LiHMDS) yielded a “kinetically induced” frustrated Lewis pair system capable of activating a variety of substrates such as ethers, amides, and ketones. These reactions demonstrate the high reactivity of (subPc)­BOTf toward organic molecules

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

Azobisisobutyronitrile Initiated Aerobic Oxidative Transformation of Amines: Coupling of Primary Amines and Cyanation of Tertiary Amines

In the presence of a catalytic amount of radical initiator AIBN, primary amines are oxidatively coupled to imines and tertiary amines are cyanated to α-aminonitriles. These “metal-free” aerobic oxidative coupling reactions may find applications in a wide range of “green” oxidation chemistry

Visible Light Induced Living/Controlled Radical Polymerization of Acrylates Catalyzed by Cobalt Porphyrins

Visible light induced living radical polymerization of a wide scope of acrylates mediated by organocobalt porphyrins was developed. The photocleavage of the Co–C bond of organocobalt porphyrin produced carbon centered radicals, which initiated polymerization, and porphyrin cobalt­(II), a persistent metal-centered radical. The organocobalt porphyrins were highly sensitive to external visible light irradiation so that photostimulus was used to control the initiation steps and regulate chain growth by reversibly activating the Co–C bond. Polymerization occurred spontaneously under irradiation and stopped promptly once shutting down light source. The scope of monomers was successfully extended from acrylamides to various hydrophobic and hydrophilic acrylates via the control of the light intensity. The structure of polyacrylate obtained was confirmed by ²D NMR, ¹³C NMR, GPC, and MALDI-TOF-MS. One of the unique features of this neat visible light induced polymerization process is that organocobalt porphyrins played dual roles of photoinitiators and mediators without addition of any dyes, photosensitizers, or sacrificial reagents

Reactivity and Mechanism Studies of Hydrogen Evolution Catalyzed by Copper Corroles

Several copper corrole complexes were synthesized, and their catalytic activities for hydrogen (H₂) evolution were examined. Our results showed that substituents at the <i>meso</i> positions of corrole macrocycles played significant roles in regulating the redox and thus the catalytic properties of copper corrole complexes: strong electron-withdrawing substituents can improve the catalysis for hydrogen evolution, while electron-donating substituents are not favored in this system. The copper complex of 5,15-pentafluorophenyl-10-(4-nitrophenyl)­corrole (<b>1</b>) was shown to have the best electrocatalytic performance among copper corroles examined. Complex <b>1</b> can electrocatalyze H₂ evolution using trifluoroacetic acid (TFA) as the proton source in acetonitrile. In cyclic voltammetry, the value of <i>i</i>_cat/<i>i</i>_p = 303 (<i>i</i>_cat is the catalytic current, <i>i</i>_p is the one-electron peak current of <b>1</b> in the absence of acid) at a scan rate of 100 mV s^–1 and 20 °C is remarkable. Electrochemical and spectroscopic measurements revealed that <b>1</b> has the desired stability in concentrated TFA acid solution and is unchanged by functioning as an electrocatalyst. Stopped-flow, spectroelectrochemistry, and theoretical studies provided valuable insights into the mechanism of hydrogen evolution mediated by <b>1</b>. Doubly reduced <b>1</b> is the catalytic active species that reacts with a proton to give the hydride intermediate for subsequent generation of H₂

Reactivity and Mechanism Studies of Hydrogen Evolution Catalyzed by Copper Corroles

Several copper corrole complexes were synthesized, and their catalytic activities for hydrogen (H₂) evolution were examined. Our results showed that substituents at the <i>meso</i> positions of corrole macrocycles played significant roles in regulating the redox and thus the catalytic properties of copper corrole complexes: strong electron-withdrawing substituents can improve the catalysis for hydrogen evolution, while electron-donating substituents are not favored in this system. The copper complex of 5,15-pentafluorophenyl-10-(4-nitrophenyl)­corrole (<b>1</b>) was shown to have the best electrocatalytic performance among copper corroles examined. Complex <b>1</b> can electrocatalyze H₂ evolution using trifluoroacetic acid (TFA) as the proton source in acetonitrile. In cyclic voltammetry, the value of <i>i</i>_cat/<i>i</i>_p = 303 (<i>i</i>_cat is the catalytic current, <i>i</i>_p is the one-electron peak current of <b>1</b> in the absence of acid) at a scan rate of 100 mV s^–1 and 20 °C is remarkable. Electrochemical and spectroscopic measurements revealed that <b>1</b> has the desired stability in concentrated TFA acid solution and is unchanged by functioning as an electrocatalyst. Stopped-flow, spectroelectrochemistry, and theoretical studies provided valuable insights into the mechanism of hydrogen evolution mediated by <b>1</b>. Doubly reduced <b>1</b> is the catalytic active species that reacts with a proton to give the hydride intermediate for subsequent generation of H₂

Production of Formamides from CO and Amines Induced by Porphyrin Rhodium(II) Metalloradical

It is of fundamental importance to transform carbon monoxide (CO) to petrochemical feedstocks and fine chemicals. Many strategies built on the activation of CO bond by π-back bonding from the transition metal center were developed during the past decades. Herein, a new CO activation method, in which the CO was converted to the active acyl-like metalloradical, [(por)­Rh­(CO)]^• (por = porphyrin), was reported. The reactivity of [(por)­Rh­(CO)]^• and other rhodium porphyrin compounds, such as (por)­RhCHO and (por)­RhC­(O)­NH^<i>n</i>Pr, and corresponding mechanism studies were conducted experimentally and computationally and inspired the design of a new conversion system featuring 100% atom economy that promotes carbonylation of amines to formamides using porphyrin rhodium­(II) metalloradical. Following this radical based pathway, the carbonylations of a series of primary and secondary aliphatic amines were examined, and turnover numbers up to 224 were obtained

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)