Abstract The substitution reactions of cis‐[PtMe,(dmso),] with pyridine (py) to produce cis‐[PtMe2py2] in toluene proceeds in two steps. In the absence of added dimethylsulfoxide (dmso), these steps can not be separated due to the rate constants being very similar. In the presence of added dmso, the rate of the first step, the formation of the monopyridine complex is retarded, which is indicative of a dissociative mechanism. A parallel associative reaction path with pyridine could also be observed. This pathway is independent of the concentration of added dmso. Above a 40‐fold excess of dmso, the dissociative pathway is suppressed and only the associative reaction occurs. A plot of Kobs vs the pyridine concentration for this pathway is linear at low [py], but shows a saturation at high [py]. This suggests that the reaction occurs via the formation of a precursor‐complex, for which the formation constant was found to be 0.32 · 0.03 M−1. The volume of activation at a high pyridine concentration is −11.4 · 0.8 cm3 mol−1, which indicates that the ligand interchange process is of the associative type. The second step, the formation of the bispyridine complex, can clearly be separated from the first reaction step. This step occurs via a dissociative mechanism, as demonstrated by the decrease in kobs with increasing pyridine concentration. The dissociation of dmso was characterized by a rate constant of (8.1 · 0.9).10−45−1 at 25°C, ·H = 116 ·9 kJ mol−1 and AS. = 86 · 29 JK−1 mol−1. At higher pyridine concentrations evidence for a parallel associative reaction was found, for which the rate constant is (1.3 · 0.2).10−3 M−1S−1 25°C. The results are discussed in reference to available literature data.

Abstract The screening of metal chlorides and metal acetylacetonates as catalysts for the oxidation of 1‐indanol by sodium percarbonate (at reflux in 1,2‐dichloroethane in the presence of small amounts of Adogen 464) has been carried out. The efficiency of the process depended on the nature of the transition metal and its oxidation state but, except for iron, was not greatly influenced by the nature of the ligands. Good conversions and yields have been obtained using PdCl2, RhCl3, RuCl3 and, particularly, MoO2(acac)2 as catalysts.

Abstract The rhodium‐catalyzed hydroformylation of 1‐hexene in THF with the linear triphosphane PhP(CH2CH2PPh2)2 [PP,] has been studied both in situ and in high‐pressure autoclaves. Sapphire NMR tubes with titanium valves have proved useful for studying the in situ reactions under conditions of relatively high syngas pressure (30–90 atm H,/CO) and temperature (60–100 C). Under conditions conducive to effective hydroformylation, the catalyst precursor [ (PP,)Rh(CO)]+ is quantitatively converted to the dicarbonyl [ (PP,)Rh(CO),]+, which is also the termination product of the catalysis. Irrespective of the syngas composition and of the total pressure, the dicarbonyl complex is the only phosphorus‐containing species detectable on the NMR time‐scale during the course of the isomerization and hydroformylation of the alkene. The PP2‐Rh catalytic system exhibits some peculiar features that may be summarized as follows. (i) Very high partial pressures of CO (120 atm) neither inhibit the hydroformylation nor affect the n/i selectivity; (ii) alkene hydrogenation occurs neither at very high partial pressures of H, (120 atm) nor in the absence of added CO; (iii) the isomerization rate is slightly faster than that of hydroformylation; (iv) terminal and internal alkenes (2‐, 3‐hexenes) are hydroformylated with comparable rates. Various control experiments have been carried out using in‐situ NMR, as well as batch experiments under different reaction conditions or with different catalyst precursors. Despite these extensive studies, unambiguous conclusions about the catalysis mechanism have not been reached. In particular, the possibility that different catalysts may be operative depending on the reaction conditions cannot be ruled out. The hydroformylation results rule out the involvement of phosphane‐free “Rh‐CO” catalysts, even under conditions of very high partial pressure of CO, and point to “(PP,)Rh(CO),” catalysts with small steric hindrance over the whole range of syngas pressures investigated.

Abstract The title compound rac‐9 and its bis(acetone) complex rac‐10 were prepared, and the latter investigated by X‐ray structure analysis. rac‐10 proves that the coordination of the weak donor acetone, an easily substitutable ligand in PTHs and related compounds, is an essential point for dissolving these coordination polymers, and thus allowing catalysis reactions in such solvents. Furthermore rac‐10 shows only a small deviation from the square‐planar coordination expected for Pd11. This indicates that the strong deviation from planarity observed in complexes with more sterically demanding, bidentate ligands is caused by steric interactions with the substituents on the PTH, rather than by electronic effects.

Abstract The synthesis of a new Diels‐Alder adduct 7 of [60]fullerene and a phthalocyaninenickel compound containing a longer spacer than the originally reported Diels‐Alder adduct 1 is described. The bisenophilic hemiporphyrazinenickel compound 11 reacts with [60]fullerene to form a Diels‐Alder adduct 12 containing two fullerene units. Spectroelectrochemical investigations of 7 and 12 reveal multiple reductions, which are attributed to the corresponding subunits of the molecules. In contrast to 1, the election acceptor properties of the [60]fullerene unit in both molecules have no influence on the electronic properties of the phthalocyanine and hemiporphyrazine, respectively.

Abstract The mononuclear starting materials [Rh(η4‐C8H12)(k2‐P,Sb‐iPr2PCH2SbR2)]PF6 (la, b) react with CF3CO2H in the presence of H2 to give the dinuclear hydridorhodium(II1) complexes [{RhH(k2‐P,Sb‐iPr2PCH2SbR2)]PF6 (2a, b) in almost quantitative yield. The X‐ray crystal structural analysis of 2b (R = tBu) reveals a distorted octahedral geometry around the two metal centers with the two phosphanyl(stibanyl)methanes in a chelating and the two trifluoracetate ligands in a bridging coordination mode.

Abstract Raman (3500‐50 cm−l) and infrared (4000‐400 cm−l) spectra of the title compound, ClSO2NPCl3, were recorded for the solid and liquid phase. Additionally, the Raman spectrum of the compound dissolved in CCl4 was obtained and qualitative depolarization values were determined. The spectra of the liquid and solid phase were interpreted in terms of the existence of only one conformation possessing C1 symmetry, as predicted by quantum chemical calculations. A complete vibrational assignment is proposed based on the relative intensities, on group frequencies along with support from the normal coordinate analysis. The experimental fundamental vibrational modes are compared to those obtained from theoretical approaches employing the ab initio MP2/6‐31G* method and a density functional approximation (B3PW91/6‐31G*).