Hydroxo complexes platinum

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)... 

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)... 

A comprehensive study of aminolysis reactions involving dinuclear platinum(II)-hydroxo complexes has been described.176 Treatment of the di-/i-hydroxo complexes of the type [Pt2-(/i-OH)2(L2)2]2+ with an excess of aryl amine RNH2 (L = PPh3, R = Ph, p-tolyl, /)-Bu Cr,I I4,... 

W-(2-Aminoethyl)-l,2-diaminoethane (dien) yields complexes [PdX(dien)]X (X = Cl or I) 204,20s a range of solvated complexes may be obtained by reaction of [Pdl(dien)] with AgC104 in the appropriate solvent. As for the platinum analogue, the aqua complex [Pd(dien)(H20)](C104)2 reacts with tetraphenylborate to yield [PdPh(dien)](BPh4). Reaction of the hydroxo complex with carbon monoxide yields C02 and palladium metal is deposited.206... 

Platinum-alkylperoxo and -hydroperoxo complexes are much less effective ketonization reagents than their palladium analogs. The platinum-hydroperoxide complex generated by protonation of Pt(PPh3)202 as in equation (90) was found to be inactive,133 as well as Pt(CF3)(OOH)(depe) obtained from the reaction of H202 with the corresponding hydroxo complex.265... 

Unexpectedly, the methoxo complex shows no tendency to decompose to a hydride by / -elimination, although it does react immediately with water to give the hydroxo complex. In contrast, cyclohexyne bis(triphenylphosphine)platinum(0) reacts with methanol to give a hydrido complex, presumably via an undetected intermediate methoxide (see Equation 3) ... 

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) ... 

The hydroxo complexes behave as strong bases in aqueous organic solvents and react with weak acids, including carbon acids such as nitromethane, methyl ketones, acetylacetone, acetonitrile, phenylacetylene and cyclopentadiene this provides a useful synthesis under mild conditions of platinum(II)-carbon a-bonded complexes, as exemplified in Equation 6 (18) ... 

Preparing trans-hydrido-alkyls or -aryls of platinum(II) does not require prior isolation of a hydroxo complex. The main routes we have used are shown in Equations 9-11, and selected spectroscopic data, including some from the literature, are in Table IV. 

The synthesis of bridging hydroxo complexes of platinum has been reported by Fakley and Pidcock (64). Treatment of bridging chloro complexes (e.g., 58) with aqueous potassium hydroxide, benzene, and a... 

A similar model for the case of thallium cuprate is complicated by the large number of parameters that affect the state of the system, and also by the necessity to introduce two experimentally unknown quantities simultaneously into the model. However, taking into account the character of the pH dependences of all the processes that occur with the participation of thallium and copper, one can suppose that the shape of the thallium cuprate stability region would be close to that for the mixed oxide. That is, its width would increase with increasing concentration of copper ions (hydroxo complexes) within the crystallization zone. Although the crystallization process took place under a fortiori non equilibrium conditions, the results of the preparative analysis agree qualitatively with the concept of stability of the products. The interval over which formation of thallium cuprate on copper substrates occurs and the formation of the mixed oxide on platinum and carbon substrates can be observed is wider for higher values of the pH [352-354]. 

ALKYL OR ARYL BIS(TERTIARY PHOSPHINE) HYDROXO COMPLEXES OF PLATINUM(II)... 

Complexes of the type [Pt(OH)RL2] (R = alkyl or aryl L2 = two mono-dentate tertiary phosphines or a bidentate ditertiary phosphine) are rare examples of monomeric, uncharged hydroxo complexes of platinum(II). Their interesting chemical properties arise from the presence of typical... 

Alkyl or Aryl Bis(tertiary phosphine) Hydroxo Complexes of Platinum(ll) 101... 

Similarly, reference is made to another more recent review (41) of the author s contributions to the chemistry of rhodium, iridium, rhenium, osmium and ruthenium alkoxo, and hydroxo complexes, following a similar earlier publication (40) on the alkoxo derivatives of platinum metals. Reference may also be made to the first X-ray structural study (265, 266) of a siloxy derivative, [(cod)Rh(/i-OSiMe)3]2. 

G. Strukul, R. A. Michelin, Catalytic epoxidation of 1-Octene with diluted hydrogen peroxide. On the basic role of hydroxo complexes of platinum(n) and related species, J. Am. Chem. Soc. 107 (1985) 7563. 

Such aquo complexes react with triphenylphosphine yielding the corresponding phosphino compound. It is noteworthy that while the dinuclear platinum complexes do not react with water to produce the hydroxo compound and the formation of this hydroxo compound requires the refluxing of the halide complexes with KOH or NBU4OH for 24 hours, the silver derivatives decompose in solution with NBU4OH and react with water under mild conditions to form the hydroxo complex. Similarly, while the dinuclear platinum complexes do not react, for instance, with tht to cleave the bridging Pt(y(i-X)Pt system, the aquo silver compound reacts with tetrahy-... 

As many carbonate complexes are synthesized usually in aqueous solution under fairly alkaline conditions, the possibility of contamination by hydroxy species is often a problem. To circumvent this, the use of bicarbonate ion (via saturation of sodium carbonate solution with COj) rather than the carbonate ion can often avoid the precipitation of these contaminants. Many other synthetic methods use carbon dioxide as their starting point. Transition metal hydroxo complexes are, in general, capable of reacting with CO2 to produce the corresponding carbonate complex. The rate of CO2 uptake, which depends upon the nucleophilicity of the OH entity, proceeds by a mechanism that can be regarded as hydroxide addition across the unsaturated C02. There are few non-aqueous routes to carbonate complexes but one reaction (3), illustrative of a synthetic pathway of great potential, is that used to prepare platinum and copper complexes. Ruthenium and osmium carbonate complexes result from the oxidation of coordinated carbon monoxide by dioxygen insertion (4). ... 

Dissolution of the bronze colored crystals of 4 (X = Cl, Br) in water yields a mixture of the diamagnetic platinum(II) and platinum(IV) materials outlined in Eq. 42. Recent data (559) suggest a more complex equilibrium is present than in Eq. 42. Preliminary evidence suggests that the rra s-Pt(CN)4X(OH)2- ion is formed upon dissolution of 4, Fig. 22 (364a, 559). This is consistent with the formation of this hydroxo complex in the aquation and subsequent hydrolysis reaction of I/ a j-Pt(CN)4X2 (X = Cl, Br) (86) and the note that Pt(II) complexes catalyze the substitution reactions of formally inert Pt(IV) complexes (34). Addition of 0.1 Af KX suppresses these interfering reactions. Fig. 22. 

Miscellaneous.— The reaction between dioxygen platinum(ii) complexes and substituted acetylenes takes place via two discernible steps, according to reaction (9), where R = COaMe and R = cyclohexyl. There is a direct attack by the acetylene on the dioxygen ligand. Formation of u-peroxo- -hydroxo-complexes... 

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