Jun-Jieh Wang

Bio: Jun-Jieh Wang is an academic researcher from Harvard University. The author has contributed to research in topics: Molybdenum & Substrate (chemistry). The author has an hindex of 4, co-authored 5 publications receiving 492 citations.

Analogue reaction systems of selenate reductase.

Abstract: Analogue reaction systems of selenate reductase, which reduces substrate in the overall enzymatic reaction SeO42- + 2H+ + 2e- → SeO32- + H2O, have been developed using bis(dithiolene) complexes of ...

Comparative kinetics and mechanism of oxygen and sulfur atom transfer reactions mediated by bis(dithiolene) complexes of molybdenum and tungsten.

Abstract: Although the kinetics and mechanism of metal-mediated oxygen atom (oxo) transfer reactions have been examined in some detail, sulfur atom (sulfido) transfer reactions have not been similarly scrutinized. The reactions [MIV(O-p-C6H4X‘)(S2C2Me2)2]1- + Ph3AsQ → [MVIQ(O-p-C6H4X‘)(S2C2Me2)2]1- + Ph3As (M = Mo, W; Q = O, S) with variable substituent X‘ have been investigated in acetonitrile in order to determine the relative rates of oxo versus sulfido transfer at constant structure (square pyramidal) of the atom acceptor and of atom transfer at constant structure of the atom donor and metal variability of the atom acceptor. All reactions exhibit second-order kinetics and entropies of activation (−25 to −45 eu) consistent with an associative transition state. At parity of atom acceptor, k2S (0.25−0.75 M-1s-1) > k2O (0.023−0.060 M-1s-1) with M = Mo and k2S (4.1−66.7 M-1s-1) > k2O (1.8−9.8 M-1s-1) with M = W. At constant atom donor and X‘, k2W > k2Mo with reactivity ratios k2W/k2Mo = 78−184 (Q = O) and 16−89 (Q =...

Silylation, sulfidation, and benzene-1,2-dithiolate complexation reactions of oxo- and oxosulfidomolybdates(VI) and -tungstates(VI).

Abstract: The synthesis and structures of two types of molecules are presented: [MVIO3 - nSn(OSiR2R')]1- (M = Mo, n = 0-3; M = W, n = 3) and [MVIO2(OSiR2R')(bdt)]1- (M = Mo, W; bdt = benzene-1,2-dithiolate). For both types, R2R' are Me3, Pri3, Ph3, Me2But and Ph2But. The complete series of oxo/sulfido/silyloxo molybdenum complexes has been prepared. Complexes with n = 0 are readily prepared by the silylation of Ag2MoO4 and sustain mono- or disulfidation with Ph3SiSH to form a species with n = 1 and n = 2, respectively. Complexes with n = 3 are accessible by the silylation of [MOS3]2-. Structures of the representative series members [MoO3(OSiPh2But)]1-, [MoO2S(OSiPh3)]1-, [MoOS2(OSiPri3)]1-, [MoS3(OSiPh2But)]1-, and also [WS3(OSiMe2But)]1-, all with tetrahedral stereochemistry, are presented. Benzene-1,2-dithiolate complexes are prepared by the reaction of [MoO3(OSiR2R')]1-with the dithiol or by the silylation of previously reported [MO3(bdt)]2-. The structures of [MoO2(OSiPh2But)(bdt)]1- and [WO2(OSiPri3)(bdt)]1- conform to square-pyramidal stereochemistry with an oxo ligand in the apical position. The role of these complexes in the preparation of site analogues of the xanthine oxidoreductase enzyme family is noted. The sulfidation reactions reported here point to the utility of Ph3SiSH and Pri3SiSH as reagents for MoVI-based oxo-for-sulfido conversions.

Proton-Coupled Electron Transfer

Abstract: ▪ Abstract Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. We review several are...

Metal Ion Modeling Using Classical Mechanics

Abstract: Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. F...

Nitrate and periplasmic nitrate reductases

Abstract: The nitrate anion is a simple, abundant and relatively stable species, yet plays a significant role in global cycling of nitrogen, global climate change, and human health. Although it has been known for quite some time that nitrate is an important species environmentally, recent studies have identified potential medical applications. In this respect the nitrate anion remains an enigmatic species that promises to offer exciting science in years to come. Many bacteria readily reduce nitrate to nitrite via nitrate reductases. Classified into three distinct types – periplasmic nitrate reductase (Nap), respiratory nitrate reductase (Nar) and assimilatory nitrate reductase (Nas), they are defined by their cellular location, operon organization and active site structure. Of these, Nap proteins are the focus of this review. Despite similarities in the catalytic and spectroscopic properties Nap from different Proteobacteria are phylogenetically distinct. This review has two major sections: in the first section, nitrate in the nitrogen cycle and human health, taxonomy of nitrate reductases, assimilatory and dissimilatory nitrate reduction, cellular locations of nitrate reductases, structural and redox chemistry are discussed. The second section focuses on the features of periplasmic nitrate reductase where the catalytic subunit of the Nap and its kinetic properties, auxiliary Nap proteins, operon structure and phylogenetic relationships are discussed.