Containing metal-hydrogen bonds

The chemistry of metalloborane compounds is vast, although most are not prepared by oxidative addition of the B—H bond to a metal complex neither do they contain metal-hydrogen bonds. The synthesis of metalloborane hydrides involves many routes, the mechanisms of which are obscure. Reactions between borohydrides and transition-metal complexes involve hydride transfer without the formation of a metal-boron bond (see 1.10.7). 

With the compounds that contain nitrogen-hydrogen bonds there are highly reactive or unstable metal compounds formed. Thus with hydrazine ... 

Most of the above reactions occur via a mechanism involving intermediates with a metal-silicon bond (i.e. silicometallics) and a metal-hydrogen bond, accompanied (or sided) only occasionally by compounds containing metal-carbon bonds (i.e. organometallics) that are characteristic of the key intermediates of transition-metal-catalyzed transformations of organic compounds (for recent reviews, see Refs [11, 13]). 

Other neutral fragments eliminated in the fragmentation processes of tris-(dimethylamino) phosphine metal carbonyl complexes appear to contain phosphorus-hydrogen bonds, e. g. 

The ET rates were determined by monitoring the appearance of the absorption band at 800 nm, obeying first-order kinetics (131). The first-order rate constant increases linearly with increasing concentration of Mg " ". The second-order rate constant (/ et) is determined from the slope of the linear plot of obs versus [Mg ] to be 1.4 X 10 M s When Fc—Q is replaced by Fc—(Me)Q, which contains no hydrogen-bond acceptor, the value (0.4 M s ) is much smaller than the et value (1.4 x 10 M s ) of the ET in Fc—Q, which is promoted not only by Mg ", but also by the hydrogen bonding between the Q" moiety and the amide proton. A variety of metal ions (M" triflates salts) can also promote ET from Fc to Q in Fc-(Me)Q (Scheme 22) (131). 

The compound is thermally unstable in solution above ca. 40°. Overheating results in isolation of a red oil, which contains no terminal metal-hydrogen bonds, from solutions which are similar in appearance to those of the desired product. 

Metal hydride reagents act as a source of H because they contain polar metal-hydrogen bonds that place a partial negative charge on hydrogen. 

Metal hydride reagent (Section 12.2) A reagent containing a polar metal-hydrogen bond that places a partial negative charge on the hydrogen and acts as a source of hydride ions (H ). 

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