Teaching Climate Change Concepts and the Nature of Science: A Library Activity to Identify Sources of Climate Change Misconceptions

A library activity was developed in which students found information about climate science misconceptions from popular and scientific literatures. As part of the activity, students developed a rubric to evaluate the credibility and type of literature sources they found. The activity prepared students to produce an annotated bibliography of articles, which they then used to create a training document about a climate science misconception for staff at a local science center. Evaluation of annotated bibliographies showed that students were able to distinguish between popular and scholarly literature but struggled to identify primary and secondary sources within the scholarly literature. In the training documents produced four weeks later, students retained information literacy skills and demonstrated aspects of scientific literacy, using language that addressed common barriers to scientific literacy such as the idea of scientific consensus. In self-assessments, students felt that they could identify and evaluate information resources related to climate science

Improving Information Literacy through Wikipedia Editing in the Chemistry Classroom: Lessons Learned

Assignments in which students edit Wikipedia may help students learn about the complexities of information creation and production, while engaging them in researching and writing about topics related to class content. This chapter presents two case studies that illustrate how Wikipedia-based activities can be designed to achieve both chemistry and information literacy learning outcomes. In both examples, faculty partnered with a librarian to implement the Wikipedia editing assignments. Through these experiences, those involved learned about Wikipedia and its community, and identified promising practices for project requirements based on formal and informal assessment and observations. Reflections are offered on the value of using Wikipedia editing assignments and concrete suggestions for creating effective projects are offered

Using the Socioscientific Context of Climate Change To Teach Chemical Content and the Nature of Science

A thematic course called “Climate Change: Chemistry and Controversy” was developed for upper-level non-STEM students. This course used the socioscientific context of climate change to teach chemical principles and the nature of science. Students used principles of agnotology (direct study of misinformation) to debunk climate change misconceptions commonly encountered in the media and politics. The culmination of the course was a service-learning project to create training documents for staff at a local science center that explained common climate misconceptions. In the process of completing this project, students gained a greater appreciation for the nature of science and learned chemical principles of electromagnetic radiation, atomic structure (isotopes), molecular structure (Lewis structures, VESPR, and polarity) spectroscopy, and stoichiometry. This paper summarizes the outcomes of the course, teaching strategies used to reach the outcomes, and strategies for incorporating agnotology and socioscientific study in science courses

Nonagostic M···H–C Interactions. Synthesis, Characterization, and DFT Study of the Titanium Amide Ti₂Cl₆[N(<i>t</i>-Bu)₂]₂

The compound Ti₂Cl₆[N­(<i>t</i>-Bu)₂]₂ (<b>1</b>) has been synthesized by treating TiCl₄ with di­(<i>tert</i>-butyl)­amine, HN­(<i>t</i>-Bu)₂. Compound <b>1</b> crystallizes in two different polymorphs from pentane, both conforming to the space group <i>P</i>2₁/<i>n</i>. In both polymorphs, <b>1</b> exhibits a close Ti···C contact of 2.634(3) Å between titanium and a γ-methyl group in one of the two <i>tert</i>-butyl groups of the bound amido ligand. Interestingly, the γ-methyl group adopts a rotational conformation that maximizes the Ti···H distances, the shortest of which are 2.36(2) and 2.62(2) Å. Even though the former distance is within the range characteristic of agostic interactions, the rotational orientation of the methyl group suggests that the Ti···H interactions are repulsive rather than attractive. DFT and NBO analysis confirms this supposition: there is no evidence of weakening of the C–H bond closest to the titanium and no evidence of significant overlap of titanium orbitals with the C–H bonding orbitals of the γ-methyl group involved in the close contact. Further evidence that the close contact is repulsive was obtained from a DFT study of a series of related complexes in which the N­(<i>t</i>-Bu)₂ ligand is replaced with a NR­(<i>t</i>-Bu) ligand, where the substituent R not involved in the close contact is Et, Me, or SiMe₃. All of these latter substituents, which are sterically smaller than a <i>t</i>-Bu group, enable the amide group to pivot in such a way as to move the <i>tert</i>-butyl group farther from the metal center. The results suggest that the short Ti···C and Ti···H distances seen crystallographically for <b>1</b> are actually the result of intraligand and interligand steric repulsions involving the amide substituent not involved in the close contact. The lack of an agostic interaction despite the close contact (and the low electron count of the Ti center) is ascribed to the strong σ- and π-donor properties of the amide and chloride ligands, which raise the energies of the empty orbitals on Ti

Through-Bond Interactions in the Diradical Intermediates Formed in the Rearrangements of Bicyclo[n.m.0]alkatetraenes

Article on through-bond interactions in the diradical intermediates formed in the rearrangements of bicyclo[n.m.0]alkatetraenes

Steric and Electronic Analyses of Ligand Effects on the Stability of σ‑Methane Coordination Complexes: A DFT Study

Developing efficient catalysts for methane functionalization is a longstanding goal in inorganic chemistry. Here, we present theoretical calculations to support efforts to synthesize σ-methane complexes that can be studied by NMR spectroscopy. The systems studied are osmium complexes of stoichiometry (C5R5)Os(diphosphine)(CH3)(H)+: when both cyclopentadienyl and diphosphine are relatively strong electron donors, the methyl/hydride structure is in rapid equilibrium with its σ-methane tautomer at low temperatures, as shown experimentally some years ago. Here, using density functional theory, we examine how changing the steric and electronic properties of the ancillary cyclopentadienyl and diphosphine ligands affects the relative energies of the two tautomers, with the goal of identifying a ligand set for which the σ-methane structure, rather than the methyl/hydride form, is the predominant species in equilibrium. We also examine how varying the ancillary ligands affects the barrier for methane dissociation. The calculations suggest that osmium complexes bearing weakly donating and sterically undemanding ligands stabilize the σ-methane structure both relative to its methyl/hydride tautomer and toward dissociation of the methane ligand. More specifically, osmium σ-methane complexes of fluorinated diphosphines (CF3)2PCH2P(CF3)2 and (CF3)2PCF2P(CF3)2 are predicted to be stable enough to be observed by variable-temperature NMR spectroscopy

Steric and Electronic Analyses of Ligand Effects on the Stability of σ‑Methane Coordination Complexes: A DFT Study

Developing efficient catalysts for methane functionalization is a longstanding goal in inorganic chemistry. Here, we present theoretical calculations to support efforts to synthesize σ-methane complexes that can be studied by NMR spectroscopy. The systems studied are osmium complexes of stoichiometry (C5R5)Os(diphosphine)(CH3)(H)+: when both cyclopentadienyl and diphosphine are relatively strong electron donors, the methyl/hydride structure is in rapid equilibrium with its σ-methane tautomer at low temperatures, as shown experimentally some years ago. Here, using density functional theory, we examine how changing the steric and electronic properties of the ancillary cyclopentadienyl and diphosphine ligands affects the relative energies of the two tautomers, with the goal of identifying a ligand set for which the σ-methane structure, rather than the methyl/hydride form, is the predominant species in equilibrium. We also examine how varying the ancillary ligands affects the barrier for methane dissociation. The calculations suggest that osmium complexes bearing weakly donating and sterically undemanding ligands stabilize the σ-methane structure both relative to its methyl/hydride tautomer and toward dissociation of the methane ligand. More specifically, osmium σ-methane complexes of fluorinated diphosphines (CF3)2PCH2P(CF3)2 and (CF3)2PCF2P(CF3)2 are predicted to be stable enough to be observed by variable-temperature NMR spectroscopy

Molecular Orbitals of the Oxocarbons (CO)_<i>n</i>, <i>n</i> = 2–6. Why Does (CO)₄ Have a Triplet Ground State?

Cyclobutane-1,2,3,4-tetrone has been both predicted and found to have a triplet ground state, in which a b_2g σ MO and an a_2u π MO are each singly occupied. The nearly identical energies of these two orbitals of (CO)₄ can be attributed to the fact that both of these MOs are formed from a bonding combination of C–O π* orbitals in four CO molecules. The intrinsically stronger bonding between neighboring carbons in the b_2g σ MO compared to the a_2u π MO is balanced by the fact that the non-nearest-neighbor, C–C interactions in (CO)₄ are antibonding in b_2g, but bonding in a_2u. Crossing between an antibonding, b_1g combination of carbon lone-pair orbitals in four CO molecules and the b_2g and a_2u bonding combinations of π* MOs is responsible for the occupation of the b_2g and a_2u MOs in (CO)₄. A similar orbital crossing occurs on going from two CO molecules to (CO)₂, and this crossing is responsible for the triplet ground state that is predicted for (CO)₂. However, such an orbital crossing does not occur on formation of (CO)_2<i>n</i>+1 from 2<i>n</i> + 1 CO molecules, which is why (CO)₃ and (CO)₅ are both calculated to have singlet ground states. Orbital crossings, involving an antibonding, b₁, combination of lone-pair MOs, occur in forming all (CO)_2<i>n</i> molecules from 2<i>n</i> CO molecules. Nevertheless, (CO)₆ is predicted to have a singlet ground state, in which the b_2u σ MO is doubly occupied and the a_2u π MO is left empty. The main reason for the difference between the ground states of (CO)₄ and (CO)₆ is that interactions between 2p AOs on non-nearest-neighbor carbons, which stabilize the a_2u π MO in (CO)₄, are much weaker in (CO)₆, due to the much larger distances between non-nearest-neighbor carbons in (CO)₆ than in (CO)₄