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1. The Prototypical Transition Metal Carbenes, (CO) ₅ Cr=CH ₂ , (CO) ₄ Fe=CH ₂ , (CO) ₃ Ni=CH ₂ , (CO) ₅ Mo=CH ₂ , (CO) ₄ Ru=CH ₂ , (CO) ₃ Pd=CH ₂ , (CO) ₅ W=CH ₂ , (CO) ₄ Os=CH ₂ , and (CO) ₃ Pt=CH ₂ : Challenge to Experiment

   https://doi.org/10.1021/acs.jpca.8b05394  

   Weidman, Jared D.; Estep, Marissa L.; Schaefer, Henry F. (July 2018, The Journal of Physical Chemistry A)
2. Sub-Doppler infrared spectroscopy of resonance-stabilized hydrocarbon intermediates: ν ₃ / ν ₄ CH stretch modes and CH ₂ internal rotor dynamics of benzyl radical

   https://doi.org/10.1039/c7cp05776h  

   Kortyna, A.; Samin, A. J.; Miller, T. A.; Nesbitt, D. J. (January 2017, Physical Chemistry Chemical Physics)

   Highly reactive benzyl radicals are generated by electron dissociative attachment to benzyl chloride doped into a neon–hydrogen–helium discharge and immediately cooled to T rot = 15 K in a high density, supersonic slit expansion environment. The sub-Doppler spectra are fit to an asymmetric-top rotational Hamiltonian, thereby yielding spectroscopic constants for the ground ( v = 0) and first excited ( v = 1, ν 3 , ν 4 ) vibrational levels of the ground electronic state. The rotational constants obtained for the ground state are in good agreement with previous laser induced fluorescence measurements (LIF), with vibrational band origins ( ν 3 = 3073.2350 ± 0.0006 cm −1 , ν 4 = 3067.0576 ± 0.0006 cm −1 ) in agreement with anharmonically corrected density functional theory calculations. To assist in detection of benzyl radical in the interstellar medium, we have also significantly improved the precision of the ground state rotational constants through combined analysis of the ground state IR and LIF combination differences. Of dynamical interest, there is no evidence in the sub-Doppler spectra for tunneling splittings due to internal rotation of the CH 2 methylene subunit, which implies a significant rotational barrier consistent with partial double bond character in the CC bond. This is further confirmed with high level ab initio calculations at the CCSD(T)-f12b/ccpVdZ-f12 level, which predict a zero-point energy corrected barrier to internal rotation of Δ E tun ≈ 11.45 kcal mol −1 or 4005 cm −1 . In summary, the high-resolution infrared spectra are in excellent agreement with simple physical organic chemistry pictures of a strongly resonance-stabilized benzyl radical with a nearly rigid planar structure due to electron delocalization around the aromatic ring. 

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3. Correction: Sub-Doppler infrared spectroscopy of resonance-stabilized hydrocarbon intermediates: ν ₃ / ν ₄ CH stretch modes and CH ₂ internal rotor dynamics of benzyl radical

   https://doi.org/10.1039/c9cp90148e  

   Kortyna, A.; Samin, A. J.; Miller, T. A.; Nesbitt, D. J. (June 2019, Physical Chemistry Chemical Physics)

   Correction for ‘Sub-Doppler infrared spectroscopy of resonance-stabilized hydrocarbon intermediates: ν 3 / ν 4 CH stretch modes and CH 2 internal rotor dynamics of benzyl radical’ by A. Kortyna et al. , Phys. Chem. Chem. Phys. , 2017, 19 , 29812–29821. 

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4. Formation of All Three C ₂ H ₄ O Isomers—Ethylene Oxide ( c -C ₂ H ₄ O), Acetaldehyde (CH ₃ CHO), and Vinyl Alcohol (CH ₂ CHOH)—in Ethanol-containing Interstellar Analog Ices

   https://doi.org/10.3847/1538-4357/adc308  

   Wang, Jia; Zhang, Chaojiang; Marks, Joshua H; Kaiser, Ralf I (May 2025, The Astrophysical Journal)

   Abstract Oxygen-containing complex organic molecules are key precursors to biorelevant compounds fundamental for the origins of life. However, the untangling of their interstellar formation mechanisms has just scratched the surface, especially for oxygen-containing cyclic molecules. Here, we present the first laboratory simulation experiments featuring the formation of all three C₂H₄O isomers—ethylene oxide (c–C₂H₄O), acetaldehyde (CH₃CHO), and vinyl alcohol (CH₂CHOH)—in low-temperature model interstellar ices composed of carbon monoxide (CO) and ethanol (C₂H₅OH). Ice mixtures were exposed to galactic cosmic-ray proxies with an irradiation dose equivalent to a cold molecular cloud aged (7 ± 2) × 10⁵yr. These biorelevant species were detected in the gas phase through isomer-selective photoionization reflectron time-of-flight mass spectrometry during temperature-programmed desorption. Isotopic labeling experiments reveal that ethylene oxide is produced from ethanol alone, providing the first experimental evidence to support the hypothesis that ethanol serves as a precursor to the prototype epoxide in interstellar ices. These findings reveal feasible pathways for the formation of all three C₂H₄O isomers in ethanol-rich interstellar ices, offering valuable constraints on astrochemical models for their formation. Our results suggest that ethanol is a critical precursor to C₂H₄O isomers in interstellar environments, representing a critical step toward unraveling the formation mechanisms of oxygen-containing cyclic molecules, aldehydes, and their enol tautomers from alcohols in interstellar ices. 

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5. Disproportionation of Sn(II){CH(SiMe ₃ ) ₂ } ₂ to ·Sn(III){CH(SiMe ₃ ) ₂ } ₃ and ·Sn(I){CH(SiMe ₃ ) ₂ }: Characterization of the Sn(I) Product

   https://doi.org/10.1039/d3cc01542d  

   Mears, Kristian; Nguyen, Gia-Ann; Ruiz, Bronson; Zou, Wenxing; Fettinger, James C; Power, Philip P (May 2023, Chemical Communications)

   Half a century since the photocatalytic disproportionation of Lappert's dialkyl stannylene SnR 2 , R = CH(SiMe 3 ) 2 (1) gave the persistent trivalent radical [·SnR 3 ], the characterization of the corresponding Sn(I) product, ·SnR is now described. It was isolated as the hexastannaprismane Sn 6 R 6 (2), from the reduction of 1 by the Mg(I)-reagent, Mg(BDI Dip ) 2 , (BDI = (DipNCMe) 2 CH, Dip + 2,6-diisopropylphenyl). 

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