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Ligand hydrido

Platinum(II) Complexes with Hydrido and Dihydrogen Ligands 6.5.4.6.1 Hydrido ligands... [Pg.718]

A robust and highly active catalyst for water-phase, acid-catalyzed THs of carbonyl compounds at pH 2.0-3.0 at 70 °C was disclosed by Ogo and coworkers [60]. The water-soluble hydride complex [Cp lr(bipy)H] (72, Cp = Tl -CsMes, bipy = 2,2 -bipyridine) was synthesized from the reaction of [Cp lr(bipy)(H20)] (73) with HCOOX (X = H or Na) in H2O under controlled pH conditions (2.0 < pH < 6.0, 25 °C). The pH control is pivotal in avoiding protonation of the hydrido ligand of 72 below pH ca. 1.0 and deprotonation of the aquo ligand of 73 above pH ca. 6.0. The rate of the reaction is heavily dependent on the pH of the solution, the reaction temperature, and the concentration of HCOOH. High TOFs of the acid-catalyzed transfer hydrogenations at pH 2.0-3.0, ranging from 150 to 525 h, were observed for a variety of linear and cyclic ketones, as summarized in Table 4.5. [Pg.80]

In particular, if we have a complex that normally has n ligands when the oxidation state of the central metal is 2, but prefers (n + 2) ligands when the oxidation state is increased to (z + 2), we have the prerequisites for facile oxidative addition of a polyatomic molecule such as H2 to form two new ligands (here, hydrido ligands, H ) by breaking a covalent bond within the molecule and taking two electrons from the metal atom M (reaction 18.9). The reverse process is called reductive elimination. [Pg.399]

None of the experiments or spectral data presented above provides good evidence for our formulation of the dimer as a tetrahydride. In fact we initially had believed the compound to be a dihydride, Rh2H2(P(iso-Pr)3)4, or possibly a monomeric monohydride, RhH(P(iso-Pr)3)2 (2, 4). The dimeric nature is proved by the crystal structure. We began to suspect the presence of more hydrido ligands after completing the structure and learning of the analogous tri-isopropylphosphite complexes studied by Sivak and Muetterties (10, 20). [Pg.129]

Further evidence for a tetrahydride comes from the reaction of a known amount of the dimer with an excess of 1-hexene. After several hours the amount of hexane produced was 1.4 0.2 mmol of hexane per millimole of dimer (gas chromatography (GC) analysis). This suggests a rather complicated reaction but requires more than one hydrido ligand per rhodium center. The nature of the reaction and the resulting residual compound(s) are still under investigation. [Pg.130]


See other pages where Ligand hydrido is mentioned: [Pg.64]    [Pg.66]    [Pg.174]    [Pg.185]    [Pg.165]    [Pg.674]    [Pg.689]    [Pg.707]    [Pg.720]    [Pg.1074]    [Pg.1074]    [Pg.1253]    [Pg.1284]    [Pg.465]    [Pg.243]    [Pg.254]    [Pg.274]    [Pg.8]    [Pg.169]    [Pg.475]    [Pg.237]    [Pg.373]    [Pg.375]    [Pg.376]    [Pg.376]    [Pg.377]    [Pg.666]    [Pg.668]    [Pg.696]    [Pg.697]    [Pg.697]    [Pg.699]    [Pg.226]    [Pg.227]    [Pg.400]    [Pg.241]    [Pg.120]    [Pg.121]    [Pg.122]    [Pg.1015]    [Pg.1316]    [Pg.243]    [Pg.292]    [Pg.169]    [Pg.121]    [Pg.122]   
See also in sourсe #XX -- [ Pg.812 , Pg.815 ]




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