We present the ground-and excited-state Raman spectra of trans-4,4'-diphenylstilbene (DPS). We analyze the spectra on the basis of comparison with the Raman spectra of the ground-and excited-state and anion radical spectra of trans-stilbene and biphenyl. The excited-state Raman spectra of DPS in methylene chloride and dioxane exhibit mode-specific, solvent-dependent dynamics. Specifically, the intensities of several vibrational modes associated with the biphenyl portion of DPS are solvent dependent. We attribute the change in intensity to a variation in the Franck-Condon overlap between SI and S, caused by differences in the planarity of the biphenyl portion of DPS in the two solvents. The lower viscosity solvent, methylene chloride, results in a more planar SI structure of DPS than does dioxane. However, the rate at which the SI geometry achieves equilibrium is slower in methylene chloride than it is in dioxane. This result suggests that dielectric stabilization of SI DPS by the solvent, not viscosity, controls the conformational dynamics.

The He I photoelectron spectra of M2(form)4 (M = Cr, Mo, W; form = N,N‘-diphenylformamidinate) and Mo2(cyform)4 (cyform = N,N‘−dicyclohexylformamidinate) are presented. For comparison, the Ne I, He I, and He II photoelectron spectra of Mo2(p-CH3-form)4 have also been obtained. The valence ionization features of these molecules are interpreted based on (1) the changes that occur with the metal and ligand substitutions, (2) the changes in photoelectron cross sections with excitation source, and (3) the changes from previously studied dimetal complexes. These photoelectron spectra are useful for revealing the effects that better electron donor ligands have on the valence electronic structure of M2(L⌒L)4 systems. Comparison with the He I spectra of the isoelectronic M2(O2CCH3)4 compounds is particularly revealing. Unlike with the more electron-withdrawing acetate ligand, several formamidinate-based ionizations derived from the nitrogen pπ orbitals occur among the metal−metal σ, π, and δ ionization bands. Although these formamidinate-based levels are close in energy to the occupied metal−metal bonds, they have little direct mixing interaction with them. The shift of the metal−metal bond ionizations to lower ionization energies for the formamidinate systems is primarily a consequence of the lower electonegativity of the ligand and the better π donation into empty metal levels. The metal−metal δ orbital experiences some additional net bonding interaction with ligand orbitals of the same symmetry. Also, an additional bonding interaction from ligand-to-metal electron donation to the δ* orbital is identified. These spectra suggest a greater degree of metal−ligand covalency than in the related M2(O2CCH3)4 systems. Fenske−Hall molecular orbital and density functional (ADF) calculations agree with the assignment and interpretation of these spectra. Calculated ionization energies are reported for M2(form)4 based on several different density functionals and with different orientations and substitutions for the phenyl rings. It is found that good estimates of the ionization energies are obtained when the truncated system M2(HN(CH)NH)4, in which the phenyl groups are replaced by hydrogen atoms, is employed.

The switch to distance learning as a result of the COVID-19 pandemic has required chemistry instructors to quickly adapt and innovate to provide remote instruction as effectively as possible. With minimal advance notice, developing and delivering online lecture materials that are engaging and laboratory activities that approximate a hands-on experience has certainly been an all-around challenge. Creating content that ensures the inclusion and success of all students, including those who are deaf and hard-of-hearing (D/HH), requires a great deal of consideration to be effective under any circumstances. To be sure, mainstream courses that are inclusive of D/HH learners necessitate, at the very least, the successful inclusion of access services (interpreters and captionists). However, in these abnormal times, an online instructional environment that accommodates D/HH students’ preferences and abilities and that is attentive to the unique social and emotional challenges that many of these students are experiencing must be established. Our campus provides both direct instruction and mainstream instructional environments for D/HH students, giving us unique perspectives on how to instruct and support students with the pandemic-forced switch to online learning. With this communication, we endeavor to share these observations and experiences with other chemistry faculty so that they may support D/HH students in their own classrooms and laboratories.

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