Hydrido compounds

Evidence has shown that supposed M02XI anions to be, in fact, Mo2XgH with bridging hydrogen atoms. The formation of MojXgH can be considered as a combination of reactions (4) and (5). 

The latter reaction can be regarded formally as an oxidative addition of HBr to Mo2Br. A structural comparison of the pairs of Mo2X /Mo2XgHH anions shows that replacement of one Cl or Br bridge by a H atom increases substantially the M-M interaction, presumably due to relief of steric compression.  

Reaction of [W(CO)3pic] with certain unidentate tertiary phosphines affords a convenient route to HW(CO)2(PR3), whereas with pyridine, HW(CO)3(py)(pic) is formed. On the basis of spectroscopic studies and supposing a rigid molecule, a pentagonal bipyramid was postulated for HW(CO)3(py)(pic). ° Oxidation of M(CO)2-dpm (M = Mo or W) with 02/HClO resulted in the formation of seven-co-ordinate hydrido complexes [MH(C0)2(dpm)2]C104, for which a capped octahedron is favoured, although the pentagonal bipyramid is not entirely discounted. 

MO calculations on (7i-Cp)2MH2 (M = Mo or Cr) have allowed energy level diagrams to be constructed and the orbital characteristics of various LUMO and HOMO tabulated. The HOMO was found to have high metal character. 

Dinitrogen Complexes.—The complex /ManJ-[Mo(N2)2(dppe)2] has been shown by electrochemical methods to decompose with the loss of both N2 ligands in THF-MeOH-O.lMLiX (X = Cl or CIOJ to produce Mo° and Mo species which further 

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In contrast, C-H coupling has been observed from the mixed methyl (hydrido) compounds TpR2PtMeH2 and TpR2PtMe2H.This reactivity and... 

On protonation with H[Bp4] OEt2 in THF the anionie trinuclear metal eom-plexes 5 and 7 afford the neutral hydrido compounds [2,2-(CO)2-7,ll-(p-H)2-2,7,... 

The major obstacle of the hydride transfer reaction is the steric bulk of the trityl cation as the reagent of choice. Substrates that will allow the isolation of cations RsE, free from intramolecular and/or intermolecular interactions with solvent molecules or anions, need to have bulky substituents and therefore the hydride transfer reaction between the hydride and trityl cation is severely hampered or it is even impossible. Another drawback of this method is the limited availability of the starting hydrido compound, which for example, is not available for lead compounds, due to the high reactivity of lead(IV) hydrides. 

This yellow, diamagnetic complex provides one of the few examples of metal hydrido compounds which contain only saturated ammine ligands. Osmiuin(v).—Further Os -arylimido-complexes have been synthesized via the reaction of phosphinimines with [OsOCl3(PPh3)2] ... 

Various tungsten-hydrido compounds prepared on silica [38], silica-alumina [39] or alumina [40] supports have been tested in propane metathesis under batch conditions to compare their properties with those of the silica or alumina-supported tantalum hydride(s) 3 [41]. 

The bidentate oxazoline ligands 85 and 86 (and derivatives thereof) are excellent reporter ligands, and several studies have used NOEs to determine the nature of their chiral pockets [61, 113, 114, 126]. NOESY studies on the cations [Ir(l,5-COD)(86)]+ and several cationic tri-nudear Ir(iii)(hydrido) compounds [110], e. g. [Ir3(p3-H)(H)5(86)3] +, 87, in connection with their hydrogenation activity, allowed their 3-D solution structures to be determined. In addition to the ortho P-phenyl protons, the protons of the oxazoline alkyl group are helpful in assigning the 3-D structure of both the catalyst precursors and the inactive tri-nudear dusters. Specifically, for one of these tri-nudear Ir(iii) complexes, 87 [110], with terminal hydride ligands at d -17.84 and d -21.32 (and a triply bridging hydride at 5 -7.07), the P-phenyl and oxazoline reporters define their relative positions, as shown in Scheme 1.5. 

A few representative examples of simple organometallic compounds of nickel(II) including carbonyl and hydrido compounds are reported here. A more complete listing of such types of compound is given in Comprehensive Organometallic Chemistry (vol. 6, p. 37) and references therein. Selected structural data for organometallic nickel(II) complexes with monodentate phosphines are reported in Table 61. 

The first six entries in this section of Table X (entries 93-98) relate to attempted insertion reactions of fluoroalkenes or fluoroalkynes into Si-Mn or Si-Fe bonds. Even in the successful cases, yields are generally low, and in some instances (e.g., entry 94) MesSiF is lost from the insertion product to leave a fluoroalkenyl manganese carbonyl. In the case of the iron hydrido compound in entry 98, there is formal loss of hydrogen to give the binuclear derivative [CljSiFelCO). ... 

The cis-hydrido compound PhaSiFelKCO eliminates triphenyl-silane when either heated alone (259) or treated with triphenylphos-phine (355). 

The chemistry of the metal carbonyl hydrides and metal carbonylates remained the principal research topic for Hieber until the 1960s. He mentioned in his account [25], that it was a particular pleasure for him that in his laboratory the first hydrido carbonyl complexes of the manganese group, HMn(CO)5 and HRe(CO)5, were prepared by careful addition of concentrated phosphoric acid to solid samples of the sodium salts of the [M(CO)5] anions, giving the highly volatile hydrido derivatives in nearly quantitative yield [45, 46]. In contrast to HCo(CO)4 and its rhodium and iridium analogues, the pentacarbonyl hydrido compounds of manganese and rhenium are thermally remarkably stable, and in... 

Several hydrido compounds of NbIV and Ta have been obtained from low-... 

Iridium hydrido compounds are particularly stable. Many of these are obtained from square M1 compounds by oxidative addition of H2 or HX. 

There are many structurally and chemically interesting hydrido derivatives of the Cp and Cp lanthanide compounds. In many of these there are double hydrido bridges (19-1), but a number of more complex structures (e.g., 19-11) are also known. The hydrido compounds are generally quite reactive and often show activity as hydrogenation catalysts. They are most commonly obtained by hydrogenolysis of Cp2LnR compounds. Ln—R bonds undergo many other reactions, of which those... 

An interesting feature of hydrido transition metal-PF3 complexes is that apart from a few dinuclear systems (Section VI) only mononuclear systems are so far known and there is as yet no corresponding chemistry analogous to that of polynuclear carbonyl hydrido compounds. The trifluorophosphine metal hydrido compounds are usually highly acidic and can readily form metallate ions such as [M(PF3)m]x and [MH(PF3) r. 

This chapter is largely concerned with the structural chemistry of Fe, Co, Ni, Pd, and Pt, for the most part in finite complexes. The structures of the simpler compounds of these and other transition metals have been described under Halides, Oxides, etc. in the appropriate chapters. Other groups of compounds described in earlier chapters include hydrido compounds, oxo-, peroxo-, and superoxo-compounds, carbonyls, and nitrosyls, in Chapters 11, 12, and 18, respectively. We note here a few general points. 

The benzylidene complex [Ru=CHPh(Cl)(Bp)(CgHi4)(PCy3)], octahedral, exhibits an agostic Ru H-C interaction and displays catalytic activity for the ring closing metathesis of diethyl-malonate in the presence of CuCl as a cocatalyst in refluxing toluene.27 The crystal structure of the octahedral hydrido compound [Rn(Bp)(H)(C0)(AsPh3)2]-H20 has been reported.28... 

The hydrido compounds of Pt11 are usually air-stable, colorless, crystalline solids, soluble in organic solvents and sublimable. Their chemical reactions resemble those of other hydrido species. They will also add HC1 or CH3I to give octahedral Ptiv complexes, but these usually readily lose the added molecules. 

As for the hydrido compounds, the nmr spectra of alkyl complexes have been studied in detail.35 It may be noted that platinum acetylacetonate complexes often have Pt—C bonds to the "/-carbon atom rather than the usual metal—oxygen bonding, and the acetylacetonate is thus unidentate as in PtCl(acac) (diphos).36... 

The corresponding neutral hydrido compound has been reported. 

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