Cyclopentadienes bearing varying length fluorinated “ponytails”, C5H5[(CH2) n (CF2) m F] ([n.m] = [0.8], [0.10], [0.12], [2.6], [2.8], and [2,10]) have been prepared by reaction of the corresponding fluoroalkyl iodides and triphenylphosphine with nickelocene. From these, the 1,1‘-bis[2.6]-, 1,1‘-bis[2.8]-, and 1,1‘-bis[2.10]-disubstituted ferrocenes and [2.10]-substituted [Mn(CO)3L], [Re(CO)3L], and [Co(CO)2L] derivatives (L = η5-C5H4[2.10]) were prepared. Although the anions of the [0.m] compounds were thermally unstable, the corresponding [0.8], [0.10], and [0.12] cobalt dicarbonyl complexes were prepared directly from the cyclopentadienes. The solubilities of these compounds in both saturated fluorocarbon (fluorous) and conventional solvents was found to depend strongly on the length of the fluoroalkyl tail and on the temperature. These compounds all dissolve in fluorous solvents, and the 1,1‘-bis[2.10]ferrocene partitions selectively into the fluorous layer of a biphasic perfluoro(methylcyclohexane)/toluene system. The oxidation potentials of the 1,1‘-, bis[2.6]-, and 1,1‘-bis[2.10]ferrocenes are only very slightly more positive than ferrocene itself, demonstrating that the C2H4 spacer effectively insulates the electron-withdrawing effect of the fluoroalkyl part of the ponytail from the metal. A similar insulating effect is noted in the carbonyl stretching frequencies of [Mn(CO)3L], [Re(CO)3L], and [Co(CO)2L] derivatives (L = η5-C5H4[2.10]), which are slightly to low energy of those in the corresponding parent cyclopentadienyl analogues. In contrast, the corresponding frequencies in [Co(CO)2L] derivatives (L = η5-C5H4[0.10]; η5-C5H4[0.12]) without the hydrocarbon spacer group are at higher energy than the parent compound.

Students enter college chemistry courses with different sources of motivation, appropriate or inappropriate assumptions about their probability of success and how to study. This study is theoretically aligned with self-regulated learning research. Clearly, academic performance is closely related to student motivational beliefs and learning strategies. This study investigated the motivational beliefs and learning strategies of 2 years of college students in the second semester of organic chemistry. Responses to the Motivational Beliefs and Learning Strategies Questionnaire indicated that student selfefficacy was highly correlated with academic performance (semester grades). Gender differences were quite pronounced. Male academic performance was associated with intrinsic motivation as well as the importance placed on the learning task. Test anxiety was negatively associated with male grades. Extrinsic motivation was negatively correlated with female grades. Responses to students' sense of control over learning, the value of the learning task, and self-efficacy were significantly higher for males compared to females. Faculty who attend to these different patterns may influence beliefs as well as learning strategies. Correcting erroneous assumptions about how to learn chemistry may help students shift both their attitudes and their learning practices. The notable gender difference suggests that female chemistry students may especially profit from focused faculty intervention.

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The pK a of the 18-electron complexes [Fe(η5-C5R5)(η6-C6Me6)][PF6] {1a[PF6] (R = H) and 1b[PF6] (R = Me)} and [Fe(η5-C5R5)(η6-C6H5CHPh2)][PF6] {1c[PF6]} have been determined by the direct method in DMSO using bases with known pK a values and found to be 12−14 pK a units lower than the pK a of the free arenes, illustrating the electron-withdrawing character of the CpFe+ and Cp*Fe+ groups. Access to the pK a values for 16-, 17-, 19-, and 20-electron iron-sandwich complexes of this type with various arene structures was available by means of thermodynamic diagrams using the standard redox potentials of the oxidation and reduction of the 18-electron cations 1 + and the deprotonated complexes 2. For instance, the pK a of the 19-electron iron complex 1a (43.5) is about the same as that of free C6Me6 (43−44) whereas that of 1b is even slightly higher (46.4). The pK as of the anionic 20-electron complexes 1a - and 1b - are 7 and 12 units, respectively, higher than that of C6Me6. The pK as of 1 2+ are around −10, whereas those of 1a 3+ were estimated to be around −50. In summary, the pK as were determined for the five isostructural oxidation states FeIV to Fe0, those of FeIV being more than 110 pK a units lower than those of Fe0. The benzylic C−H bond dissociation energies (BDEs) of the 18-electron complexes have been determined by means of a thermodynamic cycle using the pK a values and standard oxidation potentials of the deprotonated forms measured in DMSO. These BDE values are between 81 and 86 kcal/mol, i.e. approximately the same as that of the free arene. The benzylic C−H BDEs in the 19- and 20-electron complexes 1 and 1 - have been determined using other thermodynamic diagrams and are 20 kcal/mol lower than in the 18-electron complexes, indicating the ease of these H-atom abstraction reactions. This trend is well taken into account by the fact that the valence shells of the metals are one unit closer to 18 in the products resulting from H-atom abstraction than in the starting paramagnetic complexes. For the 17-electron complexes, the BDEs were estimated to be only between 47 and 51 kcal/mol. We propose this stabilization of the corresponding dicationic C−H activated species to be due to coordination of the exocyclic double bond reminiscent of the structure of ferrocenyl carbonium cations.