Yun Ho Lee

A T-shaped Ni^I complex was synthesized using a rigid acridane-based pincer ligand to prepare a metalloradical center. Structural data displays a nickel ion is embedded in the plane of a PNP ligand. Having a sterically exposed half-filled dx2-y2 orbital, this three-coordinate Ni^I species reveals unique open-shell reactivity including the homolytic cleavage of various σ-bonds, such as H-H, N-N, and C-C.

In recent years considerable attention has been paid to ferrate (Fe(VI)), +6 oxidation state of iron due to its novel properties such as oxidizing power, selective reactivity, stability as salt, and non-toxic by-products of ferric ion. Especially, much progress has been made on its applications to water treatments as efficient oxidant, coagulant and disinfectant. Reflecting the increasing interests on applications of Fe(VI) as a green chemical, this paper reviewed extensively not only the chemis

A series of monocarbonyl iron complexes in the formal oxidation states 0, +1, and +2 are accessible when supported by a tetradentate tris(phosphino)silyl ligand (SiP(iPr)(3) = [Si(o-C(6)H(4)PiPr(2))(3)](-)). X-ray diffraction (XRD) studies of these carbonyl complexes establish little geometrical change about the iron center as a function of oxidation state. It is possible to functionalize the terminal CO ligand of the most reduced carbonyl adduct by addition of SiMe(3)(+) to afford a well-define

An uncommon nickel dinitrogen adduct and its tendency toward CO2 binding are investigated using a (PP(Me)P)Ni scaffold. (PP(Me)P)Ni(N2) (1) and {(PP(Me)P)Ni}2(μ-N2) (2) were prepared and their treatment with CO2 revealed the formation of (PP(Me)P)Ni(η(2)-CO2) (3). This is a new type of CO2 binding for a zero-valent nickel center supported by three donor ligands, reminiscent of the CODH active site environment. Clear unique structural differences in 3 are evident when compared with previous 4-coo

Reactions of nickel complexes supported by an anionic PNP pincer ligand (PNP – = N[2-P i Pr 2 -4-Me-C 6 H 3 ] 2 ) toward CO 2 and CO are investigated, particularly for interrogating their C–O bond formation/cleavage chemistry. The formation of a nickel formate species ( 2 ) was accomplished by the reaction of (PNP)NiH with CO 2, while the structural isomer complex (PNP)NiCOOH-κ C ( 4 ) was successfully produced from the corresponding nickel hydroxyl compound by exposing it to CO(g). Its structur

Reversible transformations are observed between a phosphide-nickel(II) alkoxide and a phosphinite-nickel(0) species via a P-O bond formation coupled with a 2-e(-) redox change at the nickel center. In the forward reaction, the nickel(0) dinitrogen species (PP(OMe)P)Ni(N2) (2) and {(PP(OMe)P)Ni}2(μ-N2) (3) were formed from the reaction of (PPP)NiCl (1) with a methoxy anion. In the backward reaction, a (PPP)Ni(II) moiety was regenerated from the CO2 reaction of 3 with the concomitant formation of

Addition of CO 2 to a low-valent nickel species has been explored with a newly designed acri PNP pincer ligand ( acri PNP – = 4,5-bis(diisopropylphosphino)-2,7,9,9-tetramethyl-9 H -acridin-10-ide). This is a crucial step in understanding biological CO 2 conversion to CO found in carbon monoxide dehydrogenase (CODH). A four-coordinate nickel(0) state was reliably accessed in the presence of a CO ligand, which can be prepared from a stepwise reduction of a cationic {( acri PNP)Ni(II)–CO} + species

We have exploited the capacity of the "(SiP(iPr)(3))Fe(I)" scaffold to accommodate additional axial ligands and characterized the mononuclear S = ½ H(2) adduct complex (SiP(iPr)(3))Fe(I)(H(2)). EPR and ENDOR data, in the context of X-ray structural results, revealed that this complex provides a highly unusual example of an open-shell metal complex that binds dihydrogen as a ligand. The H(2) ligand at 2 K dynamically reorients within the ligand-binding pocket, tunneling among the energy minima cr

The reaction of a nickel(<sc>i</sc>) carbonyl species with CH₃I revealed the formation of (PNP)NiCOCH₃ which differs from its zerovalent congener.

A nickel complex was found to be capable of stepwise reducing nitrate to dinitrogen gas using carbon monoxide as the reaction partner.

A heterobimetallic Ni-μ-CO₂-κ<italic>C</italic>:κ²<italic>O</italic>,<italic>O</italic>′-Fe species reminiscent of the CODH active site was synthesized, helping to elucidate the role of the unique iron.

Carbon dioxide conversion mediated by transition metal complexes continues to attract much attention because of its future potential utilization as a nontoxic and inexpensive C1 source for the chemical industry. Given the presence of nickel in natural systems that allow for extremely efficient catalysis, albeit in an Fe cluster arrangement, studies that focus on selective CO₂ conversion with synthetic nickel species are currently of considerable interest in our group. In this Account,

Cuprous and cupric complexes with the new imidazolyl containing tripodal tetradentate ligands {L(MIm), (1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)methanamine, and L(EIm), 2-(1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)ethanamine}, have been investigated to probe differences in their chemistry, especially in copper(I)-dioxygen chemistry, compared to that already known for the pyridyl analogue TMPA, tris(2-pyridyl)methyl)amine. Infrared (IR) stretching frequencies obtained from carbon mono

Abstract Redox‐active organometallic molecules offer a promising avenue for increasing the energy density and cycling stability of redox flow batteries. The molecular properties change dramatically as the ligands are functionalized and these variations allow for improving the solubility and controlling the redox potentials to optimize their performance when used as electrolytes. Unfortunately, it has been difficult to predict and design the stability of redox‐active molecules to enhance cyclabil