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Metal—ligand bonds deuterium

The hexakis(methyl isocyanide) dimers, [Pt2(CNMe)6], undergo photolytic cleavage of the Pt—Pt bond to give 15-electron radicals, Pt(CNMe)3.94 Mixtures of platinum and palladium dimers give rise to heteronuclear complexes under photolytic conditions. Mixtures of normal and deuterium-labeled methyl isocyanide complexes reveal that the metal-ligand bonds undergo thermal redistribution.94... [Pg.684]

A proton is the electrophile most commonly used to remove an organic ligand from a transition metal. These protonolyses typically occur by mechanisms that retain the stereochemistry of the organic ligand. For example, the deuterium in the product of the reaction in Equation 12.4 occupies the same position about the double bond as did the ruthenium in the initial vinyl complex. Olefin stereochemistry was also shown to be retained during cleavage of a vinyl-paUadium bond with Qeavage of a metal-alkyl bond has also been shown to occur with retention of stereochemistry (Equation 12.5). ... [Pg.454]

Lithium aluminum hydride reacts readily with pyridine to yield lithium tetrakis-(A/-dihydropyridyI)aluminate, LiAI(NR2)4 (structures 108 and 109).152 The NR2 groups represent 1,4-dihydro- and/or, 1,2-dihydropyridyl residues. The two diverse N-ligands may be part of the same molecule in association with the A1 metal. The structure of the adduct has been investigated by IR and NMR spectroscopy and by deuterium-labeling experiments. The latter approach has been used to determine the 1,2 to 1,4 ratio, which is found to be close to 1 2 when the reaction is carried out at room temperature. The N—A1 bond is assumed to be covalent, though of a markedly more ionic character as compared to the N—H bond in dihydropyridines.152... [Pg.383]

Pyridines in their transition metal complexes coordinate as )] (N), q (C,C), (N,C), or q ligands (Figured). By far the most common coordination mode is (N), in which the lone electron pair on the nitrogen donates to a Lewis acidic metal center (see Lewis Acids Bases). The M-N bond lies in the plane of the pyridine ring (Figure 6). Few reactivity studies of (N) pyridine ligands have been reported. One of potential interest for HDN is the base-catalyzed exchange of the pyridine protons for deuterium... [Pg.1594]

Using deuterium-labeling experiments, about 100% of the metal was shown to be active in 1-hexene polymerizations with the [rar -C2H4( 1 -lnd)2ZrMc [McB((4,f5)3] catalyst,922 and the reactivity of M-(secondary alkyl) bonds at —80 °C was comparable to that of primary alkyl metallocenes.302 These relative monomer insertion rates appear strongly ligand specific. However, when these comparisons are made, it must be borne in mind that different authors use very different catalysts, as well as different definitions of the term active center Landis defined the active... [Pg.1030]

Similarly, a 1,4-bonded Dewar pyridine was obtained in the photolysis of 2,4,6-trimethyl-3,5-bis(trifluoromethyl)pyridine. This Dewar pyridine is much less stable than the pentakis(pentafluoroethyl) counterpart. Thus, while it could be kept in a refrigerator for a few years, it isomerized to the aromatic counterpart on thermolysis. Treatment with sodium methoxide in deuteriomethanol resulted in the deuterium exchange in the a-methyl but not in the 7-methyl group, suggesting that the stability of this Dewar pyridine is partly due to the pull push interaction between the trifluoromethyl and the methyl groups on the double bond. Isomerization to the pyridine was catalyzed by acids and transition metals such as Fe or Rh. Complexes with Pd(II) or Pt(II) were isolated and determined to be square planar with a trans-N-u bond as indicated by X-ray analysis. The Dewar pyridine when coordinated as ligands on the metal isomerized to the aromatic form much faster than when noncoordinated (Scheme 36).89,90 Isomerization was... [Pg.199]


See other pages where Metal—ligand bonds deuterium is mentioned: [Pg.103]    [Pg.27]    [Pg.283]    [Pg.389]    [Pg.389]    [Pg.393]    [Pg.54]    [Pg.33]    [Pg.6346]    [Pg.215]    [Pg.249]    [Pg.6345]    [Pg.376]    [Pg.249]    [Pg.198]    [Pg.158]    [Pg.211]    [Pg.92]    [Pg.404]    [Pg.314]    [Pg.191]    [Pg.204]    [Pg.98]    [Pg.945]    [Pg.350]    [Pg.227]    [Pg.313]    [Pg.168]    [Pg.29]    [Pg.189]    [Pg.149]    [Pg.155]    [Pg.117]    [Pg.135]    [Pg.76]    [Pg.23]    [Pg.4110]    [Pg.4565]    [Pg.244]    [Pg.373]    [Pg.374]    [Pg.397]    [Pg.1570]    [Pg.70]    [Pg.490]   
See also in sourсe #XX -- [ Pg.4 , Pg.10 ]




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Ligands metal-ligand bonds

Metal deuterium

Metal-ligand bonding

Metal-ligand bonds

Metals metal-ligand bond

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