A series of novel half-sandwich M(I) and M(III) complexes (M = Co, Rh) bearing the N-heterocyclic carbene ligand 1,3-dimesitylimidazol-2-ylidene (IMes) have been prepared and characterized. Thus, (η⁵-C₅R₅)M(IMes)(C₂H₄) (M = Co, Rh; R = H, Me) were obtained from the corresponding bis(ethene) complexes (η⁵-C₅R₅)M(C₂H₄)₂, except for CpRh(IMes)(C₂H₄) which was prepared via the novel 16-electron Rh(I) compound Rh(IMes)(C₂H₄)₂Cl. The carbonyl compounds (η⁵-C₅R₅)Co(IMes)(CO) (R = H, Me) were synthesized by thermal CO substitution of (η⁵-C₅R₅)Co(CO)₂. A diamagnetic, apparently 16-electron Co(III) compound [CpCo(IMes)I]⁺[I₃ ⁻] was obtained from CpCo(IMes)(CO) and I₂. Finally, Co(III) and Rh(III) complexes CpCo(IMes)Me₂ and Cp*Rh(IMes)Me₂ were prepared by methylation of [CpCo(IMes)I]⁺[I₃ ⁻], and ligand exchange at Cp*Rh(Me₂SO)Me₂, respectively. The molecular structures of CpCo(IMes)(CO), CpRh(IMes)(C₂H₄), Cp*Rh(IMes)(C₂H₄), and Cp*Rh(IMes)Me₂ were determined by single crystal X-ray diffraction. Steric and electronic factors imposed by the strongly donating and sterically demanding IMes ligand are discussed on the basis of X-ray crystallographic, NMR, and IR spectroscopic analyses. Very poor correlations are found between values for ¹J_{Rh–C(carbene)} and dRh–C(carbene) data for Rh(I) N,N-heterocyclic carbene complexes including literature data and this work.

The aim of this study is to provide an understanding of context-based inquiry teaching within a humanistic perspective on science education by studying pre-service teachers’ beliefs about inquiry and their implementations of inquiry in their context-based teaching sequences. Therefore, five pre-service teachers enrolled in a university undergraduate course called ‘Inquiry-based chemistry education II’ (5 ECTS) were involved in an empirical case study. The pre-service teachers’ implementations of inquiry were studied from their reports on self-designed context-based inquiry teaching sequences for students age 13–15, and their beliefs by interviewing them after the course. The results indicate that the most frequent aspects of inquiry, which were implemented, were that inquiry (i) includes a context, (ii) is a way to act, (iii) is a way to think, and (iv) includes source/information evaluation and argumentation. The pre-service teachers’ beliefs about inquiry were shown to reflect manifold aspects of inquiry, such as the difficulty in explaining it. However, this difficulty in encapsulating inquiry into a clear-cut definition is not necessarily an impediment to inquiry-based teaching. Furthermore, inquiry is inherently context-bound, and context-based teaching requires extra-situational knowledge from the context and not only declarative knowledge from science. This should be considered to support effective professional development.

Electrochemical and chemical oxidation of Cp*Ir(Me₂SO)Me₂ (1; Cp* = η⁵-C₅Me₅) in Me₂SO lead to the formation of methane and traces of ethene (ratio ca. 20 ∶ 1) as well as Cp*Ir(Me₂SO)₂Me⁺. Labeling studies indicate that three of the methane hydrogen atoms arise from the iridium-bonded methyl, while the fourth appears to arise from adventitious water. By contrast, oxidation of the rhodium analog Cp*Rh(Me₂SO)Me₂ gave only ethane and Cp*Rh(Me₂SO)₂Me⁺. Quantitative derivative cyclic voltammetry (DCV) showed that the disappearance of electrode-generated 1˙⁺ follows a rate law that is second order with respect to Ir. The Rh analog 6˙⁺ reacted at rates too great to be measured by DCV under these conditions. Possible mechanisms for these reactions are discussed, and particular attention is paid to the reactivity differences between Rh and Ir. Convenient new syntheses of Cp*Ir(Me₂SO)Me₂ and Cp*Rh(Me₂SO)Me₂, as well as X-ray structure determinations of these compounds and of Cp*Ir(Me₂SO)₂Me⁺, are reported.