Tin–vanadium mixed oxides have been prepared either from V⁴⁺–Sn⁴⁺ solutions by coprecipitation, or by the solid-state reaction between SnO(OH)₂ and V₂O₅, and characterized by means of chemical analysis, FTIR spectroscopy, EPR, X-ray diffraction and surface area measurements. Interaction between the hydroxy groups of the tin oxohydrate and the vanadium ions, reduction of V⁵⁺ ions to V⁴⁺ and stabilization inside the rutile structure led to the formation of a V_xSn_1–xO₂ solid solution after calcination at 700 °C. A maximum amount of 10 atom% of vanadium entered the SnO₂ lattice; at values of up to x= 0.02, V⁴⁺ was likely to be homogeneously dispersed, while higher amounts probably formed V⁴⁺ oxide clusters inside the rutile matrix. In addition, amorphous V⁵⁺ oxide was formed over the rutile surface, and at an overall vanadium content greater than 20–25 atom% crystalline V₂O₅ was also formed. In samples where x 0.02–0.03, the solid solution was not stable at temperatures greater than 700 °C, and some of the V⁴⁺ was released from the structure forming segregated amorphous V⁵⁺ oxide, while for x < 0.02 the solution was stable. The V–Sn mixed oxides were tested as catalysts for ethane oxidative dehydrogenation. The catalysts initially exhibited an unstable behaviour due to a reduction of the V⁵⁺ oxide in the reaction environment. Tin oxide activity was enhanced by the addition of V⁴⁺; for x= 0.018, also the selectivity to ethene at temperatures higher than 480 °C was significantly greater. In contrast, selectivity to ethene at low temperatures was lower for x > 0.018.

The reactions of 2-thienyllithium (Lith) with a variety of carbyne complexes result in C–C bond formation at different sites of the molecules. The thiocarbyne cis-[Fe₂(µ-CSMe)(µ-CS)(CO)₂(Cp)₂]⁺1 (Cp = η-C₅H₅) underwent Cp addition forming [Fe₂(µ-CSMe)(µ-CS)(CO)₂(Cp)(η⁴-C₅H₅th)] 3 and trace amounts of [Fe₂(µ-CSMe)(µ-CS){C(O)th}(CO)(Cp)₂] 4. By contrast all the aminocarbynes [Fe₂(µ-CNRR′)(µ-CO)(CO)₂(Cp)₂]⁺ (R = R′ = Me 2a; R = Me, R′ = PhCH₂2b) and [Ru₂(µ-CNMe₂)(µ-CO)(CO)₂(Cp)₂]⁺6 gave the corresponding acyl derivatives [M₂(µ-CNRR′)(µ-CO)(CO){C(O)th}(Cp)₂] (M = Fe 5a and 5b; R = R′ = Me, M = Ru 7). When R ≠ R′, the NMR spectra of these neutral species show the presence of two isomers α and β arising from hindered rotation around the µ-CN bond. The relevance of these reactions is discussed in terms of selective C–C bond formation in comparison with analogous carbon nucleophile addition at [Fe₂(µ-CSMe)(µ-CO)(CO)₂(Cp)₂]⁺. The crystal structures of 3 and [Fe₂{µ-CN(Me)CH₂Ph}(µ-CO)(CO){C(O)th}(Cp)₂] 5b are reported and discussed. The conformation of the Fe₂C₂ diamond is shown to depend on the nature of the bridging ligands. Simple models of electronic structure are outlined on the basis of the geometric evidence.