Hydrido-hydroxo complexes

Complexes Resulting from Activation ofWater Hydrido(hydroxo) Complexes... 

In 1979, the first isolation of the hydrido(hydroxo) complex by oxidative addition of water to an electron-rich platinum(O) complex was accomplished by Yoshida and Otsuka [22]. Highly coordinatively unsaturated bis(triisopropylphosphine)platinum (24b) can activate water very easily at room temperature to give the hydrido(hydroxo)... 

Reactions of the hydrido(hydroxo) complex 2 with several substrates were examined (Scheme 6-14) [6]. The reactions are fairly complicated and several different types of reachons are observed depending on the substrate. Methyl acrylate and small Lewis bases such as CO, P(OMe)3, BuNC coordinate to the five-coordinated complex 2 affording the corresponding six-coordinate complexes. In reactions with the unsaturated bonds in dimethylacetylenedicarboxylate, carbon dioxide, phenylisocyanate indications for the addition across the O-H bond but not across the Os-OH bond were obtained. In reactions with olefins such as methyl vinyl ketone or allyl alcohol, elimination of a water molecule was observed to afford a hydrido metalla-cyclic compound or a hydrido (ethyl) complex. No OH insertion product was obtained. 

Schemes 6-14 Reactions of osmium hydrido (hydroxo) complex 2 with several substrates...

We also found that iridium hydrido(hydroxo) complexes like [ lrH(diphos-phine) 2( x-OH)2( x-Cl)]Cl (43) and the precursor diphosphine complexes 42 can also catalyze the hydration of nitriles. In the presence of catalyhc amounts of these complexes, heating acetonitrile and benzonitrile with excess water at 120°C gave the corresponding amides [47, 50]. 

Hydrido(hydroxo) complexes derived from the oxidative addition of HjO to [Pt(PR3)3] (26) are stronger bases than aqueous alkali in organic media. Platinum(O)... 

In the sixth chapter the activation of O-H bonds of water, alcohols and carboxylic acids, and their addition to multiple bonds is reported. Since the formally oxidative addition of ROH gives rise to hydrido(hydroxo) complexes, [MH(OR)Ln] which are postulated as intermediates in many important reactions (water gas shift reaction, Wacker-chemistry, catalytic transfer hydrogenations etc.) the authors of this chapter,... 

Hydrido-hydroxo complexes of platinum(II) are believed to be formed by reversible oxidative addition of water to bis(ligand) platinum(O) complexes containing bulky tertiary phosphines (22). Although the equilibrium favors the platinum(O) complex, trans-[PtH(OH)(P(iso-Pr)3)2] has been isolated and identified spectroscopically (see Equation 5) ... 

A range of Ru hydrido/hydroxo complexes are known, e.g. [RuH(OH)(PPh3)2 solvent] (solvent = H20, THF) (see Section 45.5.4.7.ii for details) and the related [RuH(SR)(PPh3)3] (R = H, Me, Ph, PhCH2) have been prepared (see Section 45.5.4.8.i). The sulfoxide complexes [RuHCl(DMSO)2(tri-phos)], [RuHQ(DMSO)(tet-1 )],1540 [RuHCl(DMSO)2(AsPh3)2], [RuHCl(DMSO)(AsMePh2)3] and [RuHCl(DMSO)(AsMe2Ph)3],5n are also reported. 

Milstein and coworkers reported that, in a similar manner to aliphatic alcohols, water could also be activated using complex 36 with the dearomatized PNN backbone (Scheme 39). Upon reaction with water at room temperature, aromatization takes place to quantitatively form the irafis-hydrido-hydroxo complex 37. Thermal activation of a second... 

---