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Free, publicly-accessible full text available November 1, 2026
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Previously unobserved (carbamoyl)disulfanyl chlorides were prepared by (i) addition of limiting aromatic secondary amine to (chlorocarbonyl)disulfanyl chloride; (ii) Harris reactions of sulfur dichloride with appropriate O-alkyl N-methyl-N-arylthiocarbamates; and (iii) regiospecific chlorolysis of bis(N-methyl-N-arylcarbamoyl)disulfanes. The newly synthesized unstable species were observed in situ by 1H NMR and were trapped with alkenes, thiocarbamates, and thiols using methods precedented by the chemistry of analogous (carbamoyl)sulfenyl chlorides. Furthermore, each of the trapped products was synthesized by an alternate route, reinforcing conclusions about their structures. While (N-methyl-N-phenylcarbamoyl)disulfanyl chloride was unstable and decomposed quickly or cyclized intramolecularly, introduction of the N,2,6-trimethylphenyl moiety led to significantly improved stability. As part of this study, an interesting, unexpectedly stable 1,2,4-dithiazinone was discovered and its structure was established by X-ray crystallography. The new heterocycle, with its twisted out-of-plane disulfide bond in a six-membered ring, readily donated a sulfur atom to triphenylphosphine; this reaction resulted in the formation of triphenylphosphine sulfide, along with the corresponding highly stable heterocycle in which the single sulfur that remains is part of a planar five-membered ring, fused to a co-planar aryl moiety.more » « lessFree, publicly-accessible full text available October 1, 2026
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We investigate the anisotropic thermal expansion behavior of a co- crystalline system composed of 4,40-azopyridine and trimesic acid (TMA-azo). Using variable-temperature single-crystal X-ray diffrac- tion (SC-XRD), low-frequency Raman spectroscopy, and terahertz time-domain spectroscopy (THz-TDS), we observe significant temperature-induced shifting and broadening of the vibrational absorption features, indicating changes in the intermolecular potential. Our findings reveal that thermal expansion is driven by anharmonic interactions and the potential energy topography, rather than increased molecular dynamics. Density functional the- ory (DFT) simulations support these results, highlighting significant softening of the potential energy surface (PES) with temperature. This comprehensive approach offers valuable insights into the relationship between structural dynamics and thermal properties, providing a robust framework for designing materials with tailored thermal expansion characteristics.more » « less
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A series of pyridine dipyrrolide actinide(IV) complexes, (MesPDPPh)AnCl2(THF) and An(MesPDPPh)2 (An = U, Th, where (MesPDPPh) is the doubly deprotonated form of 2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine), have been prepared. Characterization of all four complexes has been performed through a combination of solid- and solution-state methods, including elemental analysis, single crystal X-ray diffraction, and electronic absorption and nuclear magnetic resonance spectroscopies. Collectively, these data confirm the formation of the mono- and bis-ligated species. Time-dependent density functional theory has been performed on all four An(IV) complexes, providing insight into the nature of electronic transitions that are observed in the electronic absorption spectra of these compounds. Room temperature, solution-state luminescence of the actinide complexes is presented. Both Th(IV) derivatives exhibit strong photoluminescence; in contrast, theU(IV) species are nonemissive.more » « less
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