Correction: Significant differences of monooxotungsten(IV) and dioxotungsten(VI) benzenedithiolates containing two intramolecular NH···S hydrogen bonds from molybdenum analogues.

Correction for 'Significant differences of monooxotungsten(IV) and dioxotungsten(VI) benzenedithiolates containing two intramolecular NH···S hydrogen bonds from molybdenum analogues' by Taka-aki Okamura et al., Dalton Trans., 2015, 44, 18090-18100.

Significant differences of monooxotungsten(IV) and dioxotungsten(VI) benzenedithiolates containing two intramolecular NHS hydrogen bonds from molybdenum analogues.

A monooxotungsten(iv) benzenedithiolate complex containing two intramolecular NHS hydrogen bonds, (NEt4)2[W(IV)O(1,2-S2-3-t-BuNHCOC6H3)2] (1-W), was synthesized via a ligand-exchange reaction between a new starting complex, (NEt4)2[W(IV)O(SC6F5)4], and a partially deprotonated dithiol. When dithiol was used in solution, the oxo ligand was protonated and removed to afford (NEt4)2[W(IV)(1,2-S2-3-t-BuNHCOC6H3)3]. The trans isomer, trans-1-W, was crystallized, and the molecular structure was determined via X-ray analysis. Trans-1-W was gradually isomerized by heating it in solution and it eventually achieved an approximately 1 : 1 mixture of trans/cis isomers after 48 days. However, a slightly excess amount of trans isomer remained, so the isomerization rate was considerably slower than that of the molybdenum analogue. In the presence of NEt4BH4, deuteration of the NH protons was observed in acetonitrile-d3. The oxidation of both trans- and cis-1-W by Me3NO afforded the corresponding dioxotungsten(vi) complex, (NEt4)2[W(VI)O2(1,2-S2-3-t-BuNHCOC6H3)2] (2-W), as a single isomer. The contributions of the NHS hydrogen bonds to the bond distances, vibrational data, and electrochemical properties are described via comparisons with their molybdenum analogues. The results of this comparative study yielded insights into both tungsten and molybdenum enzymes.

Behavior of anionic molybdenum(IV, VI) and tungsten(IV, VI) complexes containing bulky hydrophobic dithiolate ligands and intramolecular NH···S hydrogen bonds in nonpolar solvents.

Molybdenum(IV, VI) and tungsten(IV, VI) complexes, (Et4N)2[M(IV)O{1,2-S2-3,6-(RCONH)2C6H2}2] and (Et4N)2[M(VI)O2{1,2-S2-3,6-(RCONH)2C6H2}2] (M = Mo, W; R = (4-(t)BuC6H4)3C), with bulky hydrophobic dithiolate ligands containing NH···S hydrogen bonds were synthesized. These complexes are soluble in nonpolar solvents like toluene, which allows the detection of unsymmetrical coordination structures and elusive intermolecular interactions in solution. The (1)H NMR spectra of the complexes in toluene-d8 revealed an unsymmetrical coordination structure, and proximity of the counterions to the anion moiety was suggested at low temperatures. The oxygen-atom-transfer reaction between the molybdenum(IV) complex and Me3NO in toluene was considerably accelerated in nonpolar solvents, and this increase was attributed to the favorable access of the substrate to the active center in the hydrophobic environment.

Anethole induces apoptotic cell death accompanied by reactive oxygen species production and DNA fragmentation in Aspergillus fumigatus and Saccharomyces cerevisiae.

trans-Anethole (anethole), a major component of anise oil, has a broad antimicrobial spectrum, and antimicrobial activity that is weaker than that of other antibiotics on the market. When combined with polygodial, nagilactone E, and n-dodecanol, anethole has been shown to possess significant synergistic antifungal activity against a budding yeast, Saccharomyces cerevisiae, and a human opportunistic pathogenic yeast, Candida albicans. However, the antifungal mechanism of anethole has not been completely determined. We found that anethole stimulated cell death of a human opportunistic pathogenic fungus, Aspergillus fumigatus, in addition to S. cerevisiae. The anethole-induced cell death was accompanied by reactive oxygen species production, metacaspase activation, and DNA fragmentation. Several mutants of S. cerevisiae, in which genes related to the apoptosis-initiating execution signals from mitochondria were deleted, were resistant to anethole. These results suggest that anethole-induced cell death could be explained by oxidative stress-dependent apoptosis via typical mitochondrial death cascades in fungi, including A. fumigatus and S. cerevisiae.

Selective and effective stabilization of Mo(VI)═O bonds by NH···S hydrogen bonds via trans influence.

A monooxomolybdenum(IV) complex containing two intramolecular NH···S hydrogen bonds, (NEt(4))(2)[Mo(IV)O(1,2-S(2)-3-t-BuNHCOC(6)H(3))(2)], was synthesized. The trans isomer was crystallized as the major product, and the molecular structure was determined by X-ray analysis. The trans isomer was isomerized by heating in solution to give a 1:1 mixture of trans and cis isomers. Oxidation of these isomers by Me(3)NO afforded (NEt(4))(2)[Mo(VI)O(2)(1,2-S(2)-3-t-BuNHCOC(6)H(3))(2)]. (1)H NMR analysis revealed that the dioxomolybdenum(VI) complex existed as a single isomer where both oxo ligands were trans to each of the two hydrogen-bonded thiolate ligands. The Mo(VI)═O bond was effectively stabilized by the NH···S hydrogen bond via trans influence, which was determined using resonance Raman spectroscopy. These results were supported by preliminary density functional theory calculations.