80822-03-3Relevant academic research and scientific papers
Ligand and metal effects on the enthalpies of protonation of Cp′M(PR3)(PR′3)X complexes (M = Ru or Os)
Rottink, Mary K.,Angelici, Robert J.
, p. 7267 - 7274 (2007/10/02)
Titration calorimetry has been used to determine the enthalpies of protonation (ΔHM) of 22 Cp′M(PR3)-(PR′3)X complexes (Cp′ = η5-C5H5(Cp) or η5-C5Me5(Cp*); M = Ru, Os; PR3 = PPh3, PPh2Me, PPhMe2, PMe3, P(OEt)3, dppm, dppe, dppp; X = H, Cl, Br, I) with CF3SO3H in 1,2-dichloroethane solution at 25.0°C to give Cp′M(PR3)(PR′3)(X)(H)+CF 3SO3-. Systematically changing the ligands and/or the metal in these complexes has yielded ΔHHM values for protonation at the metal that range from -14.1 kcal/mol for CpOs(PPh3)2I to -39.2 kcal/mol for CpOs(PPh2Me)2H. Metal basicities (ΔHHM) of the CpOs(PPh3)2X complexes correlate linearly with the gas-phase proton affinities of the X- ligands, both of which increase in the following order: I- - - ? H-. Substitution of a halide ligand with a hydride causes the metal basicity to increase by as much as 23.2 kcal/mol. The basicities of CpOs(PPh3)(PR3)Br complexes increase in the following order: P(OEt)333. There is a linear correlation between the basicities (ΔHHM) of the CpOs(PR3)2Br complexes and the basicities (ΔHHP) of their PR3 ligands. In a series of complexes, the Cp* ligand increases the basicity of the metal by 5.5-9.0 kcal/mol over that of the corresponding Cp derivative, and Os complexes are 6.0-8.5 kcal/mol more basic than analogous Ru complexes. Basicities of the CpOs(PR3)2(Br) and CpRu(PR3)2(H) complexes are reduced when the protonated product is contrained to have the cis, rather than trans, structure by a small-ring chelating diphosphine ligand (dppm). These studies demonstrate that the metal, ligands, and geometry of the protonated product all substantially affect the heats of protonation (ΔHHM) of Cp′M(PR3)(PR′3)X complexes.
CYCLOPENTADIENYL-RUTHENIUM AND -OSMIUM COMPLEXES. VI. FORMATION AND PROPERTIES OF DIHYDRIDO(η-CYCLOPENTADIENYL)BIS(TRIPHENYLPHOSPHINE)OSMIUM(IV) CATION. REACTION OF HYDRIDO(η-CYCLOPENTADIENYL)BIS(TRIPHENYLPHOSPHINE)OSMIUM(II) AND DIHYDRIDO(η-CYCLOPENTADIENYL)BIS(TRIPHENYLPHOSPHINE)...
Wilczewski, Tadeusz
, p. 307 - 326 (2007/10/02)
Several new compounds of the type (1+) X(1-), where X = Cl, Br, I, I3, BPh4, p-toluenesulphonate, d(+)-campho-10-sulphonate, have been obtained in the form of ion pairs or salts.The above compounds form during oxidative addition by HX acids to CpOsH(PPh3)2.The reactions are complete after several seconds, with a quantitative yield.This is in contrast to the behaviour of CpRuH(PPh3)2, where covalent CpRuX(PPh3)2 forms.Reaction of CpOsH(PPh3)2 with DCl acid (excess) gives Cl, but no Cl is formed.Refluxing CpOsBr(PPh3)2, in ethylene glycol for instance, gives a (1+) cation as a result of the dehydrogenation of the glycol.Compounds of the type, X, in solutions of polar solvents (MeOH) or halogenated hydrocarbons (e.g.CH2X2) undergo transformation to CpOsX(PPh3)2 during the reductive elimination process.In this way novel CpOsI(PPh3)2 has been obtained.In the case of the reaction of a mixture of HX + X2 with CpOsH(PPh3)2, Br3 (for Br2) and I3 (for I2) have been obtained in the form of sparingly soluble ion pars with yields of about 90percent.
