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Instructional guidance, provided using worked examples, helps the inexperienced learner cope with complex information, that may be difficult to process in limited capacity working memory. For students of chemistry, such complex information can pertain to the visualisation of structural changes in molecules throughout chemical reactions. This can be alleviated through the affordances of augmented reality (AR) technology. 3D structures are important as they have a crucial impact on the chemical and physical properties of molecules. Within a framework of Cognitive Load Theory, this study illustrates how AR-supported worked examples may enhance learning of electrophilic aromatic substitution. The participant cohort were FHEQ level 5 undergraduate students studying a module of organic chemistry. In addition, the achievement motivation of learner's was also explored, and how this may be impacted by the provision of AR technology and worked examples. The control group was provided with a copy of our worked examples that contained 2D reaction mechanism drawings. Data was collected using a combination of quantitative instruments and qualitative surveys/interviews. For this cohort of students, significant intragroup improvements, and greater normalised change values, in conceptual understanding were observed in the AR group. This was not observed in the control group. No significant intergroup differences in reported cognitive load or achievement motivation of students were found. This was unaffected when introducing prior relevant chemistry experience as a covariate. Student feedback and subsequent thematic analysis show not only the positive impacts on student engagement, but also how students convey their understanding of electrophilic aromatic substitution principles.

The chemistry foundation year at the University of East Anglia is a diverse cohort with a wide range of prior educational experience and confidence levels. A flexible learning program combining extensive online materials intended for asynchronous study and face to face peer instruction is provided. Study is divided into weekly topics. Students are directed to take a short introductory quiz at the beginning of the week, feedback on which allows them to tailor the extent of asynchronous learning to their own needs. All students attend a highly interactive synchronous teaching session which utilises active learning to develop their conceptual understanding. The week concludes with a reflective formative test. Measures of student activity on the online platform and audience response technology in the lecture theatre provide a quantitative picture of engagement with tailored blended learning, while semi-structured interviews provide qualitative insight into the student perception.

Peer Instruction (PI), a student-centred teaching method, engages students during class through structured, frequent questioning, facilitated by classroom response systems. The central feature of PI is the ConcepTest, a question designed to help resolve student misconceptions around the subject content. Within our coordination chemistry PI session, we provide students two opportunities to answer each question -- once after a round of individual reflection, and then again after a round of augmented reality (AR)-supported peer discussion. The second round provides students with the opportunity to "switch" their original response to a different answer. The percentage of right answers typically increase after peer discussion: most students who answer incorrectly in the individual round switch to the correct answer after the peer discussion. For the six questions posed, we analysed students' discussions, in addition to their interactions with our AR tool. Furthermore, we analyse students' self-efficacy, and how this, in addition to factors such as ConcepTest difficulty influence response switching. For this study, we found that students are more likely to switch their responses for more difficult questions, as measured using the approach of Item Response Theory. Students with high pre-session self-efficacy switched from right-to-wrong (p < 0.05) and wrong-to-different wrong less often, and switched from wrong-to-right more often than students with low self-efficacy. Students with a low assessment of their problem solving and science communication abilities were significantly more likely to switch their responses from right to wrong than students with a high assessment of those abilities. Analysis of dialogues revealed evidence of the activation of knowledge elements and control structures.

There is little doubt that motivation influences the extent to which individuals engage with online learning experiences. With the increasing role of digital technologies within chemistry higher education, this study illustrates how an augmented reality (AR)-supported educational escape activity (EEA), based on topics of inorganic stereochemistry, can be employed within an online environment. The design aspects of our activity were guided by principles of Self-Determination Theory (SDT)-an intrinsic-extrinsic theory of motivation. We sought to actively support the fundamental needs of competency, autonomy, and relatedness. Our control group was provided with a copy of our EEA that utilized two-dimensional drawings. Reported measures of competency were seen as a positive predictor of intrinsic motivation. However, in this study, this was not observed to be a positive predictor of academic performance. The introduction of AR, over and above the EEA, did not result in any significant differences in reported intrinsic motivation or post-test scores on our stereochemistry test instrument. Collected qualitative data suggest that participants found the activity to be useful and engaging. Through students' discussions, we have provided evidence of how design aspects of the EEA support the psychological needs satisfaction outlined by SDT. The design of our EEA provides one approach to implementing this style of learning activity, in a way that supports virtual presence and is scalable to large student cohorts.

The Grignard reagent ArF′MgBr (ArF′ = 4-(C6F5)C6F4) reacts with Me3SiCl, Me2SiCl2and Me3SnCl to give the 4-nonafluorobiphenyl group 14 complexes ArF′Me3Si, (ArF′)2Me2Si and ArF′Me3Sn respectively. ArF′Me3Sn undergoes only methyl group exchange when treated with BBr3, yielding ArF′Me2SnBr. The solid state structures of ArF′Me3Sn and ArF′Me2SnBr have been determined and exhibit the expected distorted tetrahedral geometries at tin. The reaction between three equivalents of ArF′MgBr and BF3was not selective, while one equivalent of ArF′MgBr and (ArF)2BF (ArF= C6F5) reacted cleanly to give (ArF)2ArF′B. Treatment of BCl3with three equivalents of ArF′Li, prepared at low temperature from the reaction between ArF′Br and n-BuLi, yielded (ArF′)3B. The molecular structures of the acetonitrile adducts of (ArF)2ArF′B and (ArF′)3B closely resemble that of (ArF)3B·NCMe. During the course of the boron investigations, reaction with adventitious water led to the structural characterization of (ArF′)2BOH·OH2as a hydrogen-bonded dimer. The Grignard reagent reacts selectively with ZnCl2in diethyl ether giving first [(ArF′)Zn(μ-Cl)(OEt2)]2then (ArF′)2Zn(OEt2)2, both of which have been characterised by X-ray diffraction. The corresponding reaction with HgCl2requires the use of tetrahydrofuran as the solvent and yields (ArF′)2Hg(THF)2. [ABSTRACT FROM AUTHOR]

The ammonia adduct of tris(pentafluorophenyl)boron, (C6F5)3B·NH3, is a potentially tri-functional hydrogen-bond donor. Co-crystallisation with the bases acetonitrile, pyridine, tetrahydrofuran, tetramethylethylenediamine, 15-crown-5, 1,4-diazabicyclo[2.2.2]octane (DABCO), pyrazine and 4,4′-bipyridine results, not in donor exchange, but in the formation of supermolecules assembled through hydrogen bonding to second coordination sphere acceptors. The complexes have been characterised by elemental analysis, multinuclear NMR and single-crystal diffraction methods. The solid-state architectures range in complexity, from the hydrogen bonded pairing of (C6F5)3B·NH3, with a single monodentate acceptor molecule (e.g.MeCN to form (C6F5)3B·NH3·NCMe), through complexation with all three N–H groups to the macrocycle 15-crown-5, to the formation of infinite one-dimensional chains with pyrazine and DABCO, and to two-dimensional networks with the divergent acceptor 4,4′-bipyridine. [ABSTRACT FROM AUTHOR]

The mixed-alkyl metallocene complexes (IPCF)M(Me)(CH 2SiMe 3) (M = Zr, Hf; IPCF = Me 2C(C 5H 4)(C 13H 8)) were synthesized by the reaction of (IPCF)M(Me)Cl (M = Zr, Hf) with Me 3SiCH 2MgCl. The crystal structures of (IPCF)Zr(CH 2SiMe 3) 2, (IPCF)HfMe 2, and (IPCF)Zr(Me)Cl were determined by X-ray diffraction. The kinetics of site epimerization of the ion pairs (IPCF)M(CH 2SiMe 3)(μ-Me)B(C 6F 5) 3and [(IPCF)MCH 2SiMe 3+···B(C 6F 5) 4−] (M = Zr, Hf) were studied by variable-temperature NMR spectroscopy, while the solution ground-state structures of the ion pairs [LZrCH 2SiMe 3+···B(C 6F 5) 4−] (L = SBI, IPCF; SBI = rac-Me 2Si(Ind) 2) were probed experimentally by 19F, 1H HOESY NMR spectroscopy and theoretically by DFT and molecular dynamics calculations. They reveal differences in the strength of anion interactions between the SBI and IPCF systems which may be significant for their catalytic activity. The tetraarylborate salts are stabilized by agostic interactions to ligand Si−Me moieties, with Hf > Zr. The exchange rates of both the MeB(C 6F 5) 3−and the B(C 6F 5) 4−compounds increase with increasing ion pair concentration. This acceleration is also seen on addition of excess [Ph 3C][B(C 6F 5) 4]. Pulsed-field gradient spin−echo (PGSE) NMR measurements indicated that both [(IPCF)ZrCH 2SiMe 3+···B(C 6F 5) 4−] and [(SBI)ZrCH 2SiMe 3+···B(C 6F 5) 4−] were present mainly as ion quadruples in toluene- d8/1,2-F 2C 6H 4(8/2 in volume) at millimolar concentrations and, notably, their aggregation increased to a similar extent with the addition of an excess of [Ph 3C][B(C 6F 5) 4]. The results demonstrate the formation of mixed-ion aggregates of the type {[(L)MR +···X −][CPh 3+···X −] n}. However, whereas the site epimerization rates kexof the system (SBI)ZrMe(CH 2SiMe 3)/[Ph 3C][B(C 6F 5) 4] continue to increase linearly with the total ion concentration, for (IPCF)ZrMe(CH 2SiMe 3)/[Ph 3C][B(C 6F 5) 4] mixtures kexreaches a plateau at ca. 400 s −1(at 20 °C). Measurement of site epimerization rates as a function of ion pair concentration [(A +) x(B +) 1− xX −] therefore provides evidence for the existence of a rate-limiting barrier in the IPCF system, while it is absent in others. [ABSTRACT FROM AUTHOR]

Treatment of Cp2HfCl2with two equivalents of LiNH2BH(C6F5)2in toluene solution yields Cp2Hf{NHBH(C6F5)2}, which has been crystallographically characterised. The otherwise base-free [NHBH(C6F5)2] complex is stabilised by an agostic interaction. [ABSTRACT FROM AUTHOR]

The crystalline ion-pair [TiCl(NMe2)2(NMe2H)2]+[TiCl2{NB(C6F5)3}(NMe2H)2]−, in which the anion has a triply bonded nitridoborate ligand, is formed through the multiple activation of H3N·B(C6F5)3when treated with [Ti(NMe2)3Cl]. [ABSTRACT FROM AUTHOR]