Hydrido complexes molybdenum

Hydrido complexes, gold-osmium, 27 209 iridium, 26 117, 27 19 iron, 26 244, 27 168 iron-tungsten, 26 336 manganese, 26 226 mercury-molybdenum-ruthenium,... 

The first known r -dihydrogen complexes, so-called non-classical hydrido complexes, were the molybdenum and tungsten compounds, M(CO)3(PR3)2(ti -H2) (M = Mo, W R = /-Pr) isolated for the first time by Kubas [35]. In order for the... 

The molybdenum and tungsten metals react with C5H5 to afford hydrido complexes ... 

Pentafluoropbenyl-lithium reacts with (7r-Cp)2MCl2 (M = Mo or W) to give the hydrido-complexes (51) these react with carbon tetrachloride to give (52), and thence ionic complexes (53). The and F n.m.r. spectra of the molybdenum complex (51) indicate restricted rotation of the Mo-C group, with the Afo-H proton coupled to only one or/Ao-fluorine (J = 7-4 Hz). 

The electrosynthesis of hydride complexes directly from molecular hydrogen at atmospheric pressure by reduction of Mo(II) and W(II) tertiary phosphine precursors in moderate yield has been described as also the electrosynthesis of trihydride complexes of these metals by reduction of M(IV) dihydride precursors [101,102]. Hydrogen evolution at the active site of molybdenum nitrogenases [103] is intimately linked with biological nitrogen fixation and the electrochemistry of certain well-defined mononuclear molybdenum and tungsten hydrido species has been discussed in this context [104,105]. 

Highly selective reduction of aldehydes rather than ketones, even 4-f-butylcyclohexanone, has been achieved by a binuclear hydrido molybdenum anion (Et4N[ JL-HMo2(CO)io]) and acetic acid in refluxing THF," The stable complex is readily prepared from molybdenum hexacarbonyl, which can be recovered after reduction. The full value of this reagent in synthesis remains to be established. Tributyltin hydride has been shown to be effective for the selective reduction of aldehydes in the presence of dried silica gel which acts as a mild acid catalyst," The reaction proceeded at room temperature in cyclohexane, many common functional groups were inert under these conditions. 

AsMo2C,6H , Molybdenum, tetracarbo-ny Ibis(Ti -cy clopen tadienylH (jwlimethyl-arsino)-(ji-hydrido-di-, 25 169 O4C2H2, Formic acid, (formyloxy)-iridium complex, 21 102... 

O4M02PC23H29, Molybdenum, tetracarbonyl-bis(Ti -cyclopentadienyl)(p,-di-tert-butyl-phosphido)- jL-hydrido-di, 25 168 Oghl4CioFIi23 Xanthosine palladium(II) complexes, 23 54... 

A slow addition of acid should be avoided in this preparation, since a different complex (a hydrido-carbon species)3 may then be the main product. Too great an excess of acid should also be avoided, due to the possible formation of a triprotonated product.16 The method is general for the preparation of other analogous dicarbyne-type complexes of molybdenum and tungsten, using a variety of acids (see below). 

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