Nucleophilic attack methylplatinum complexes

Relatively soon after the discovery that aqueous solutions containing PtCl - and PtClg- can functionalize methane to form chloromethane and methanol, a mechanistic scheme for this conversion was proposed (16,17). As shown in Scheme 4, a methylplatinum(II) intermediate is formed (step I), and this intermediate is oxidized to a methylplatinum(IV) complex (step II). Either reductive elimination involving the Pt(IV) methyl group and coordinated water or chloride or, alternatively, nucleophilic attack at the carbon by an external nucleophile (H20 or Cl-) was proposed to generate the functionalized product and reduce the Pt center back to Pt(II) (step III) (17). This general mechanism has received convincing support over the last two decades (comprehensive reviews can be found in Refs. (2,14,15)). Carbon-heteroatom bond formation from Pt(IV) (step III) has been shown to occur via nucleophilic attack at a Pt-bonded methyl, as discussed in detail below (Section V. A). 

Cationic methylplatinum(II)-nitrile complexes of the type m is-PtMeL2(NCR)+X have been isolated by the reaction of //vms-PtMeClL2, where L = dimethylphenylphosphine or trimethyl-arsine, with an aryl nitrile and AgX, where X = BF4, PF. Use of pentafluorobenzonitrile and 2,3,5,6-tetrafluorotetraphthalonitrile in alcohol has led to the synthesis of a series of imino ether complexes. A mechanism for imino ether formation, involving nucleophilic attack by an alcohol at a coordinated nitrile, is suggested and the course of the reaction is shown to be dependent not only on the alcohol but also on the size of the anion used.110... 

Cationic phosphine methylplatinum(ii) complexes containing 2,9-dimethyl-l,10-phenanthroline (dmphen) exhibit fluxionality owing to hemilability of the dmphen (26, Scheme 19). Apparently, this is the route involved with some counterions, but others, such as CU, involve nucleophilic attack to form a five-coordinate intermediate, which could rearrange via either a k - or a re -intermediate. One should note that 26 is not planar and the rings make a significant... 

Reductive eliminations to form alkyl carbon-heteroatom bonds from Pt(IV) occur by initial dissociation of the heteroatom ligand as an anion, followed by attack of this anion on the alkyl ligand. Most reductive eliminations to form carbon-heteroatom bonds from Pt(IV) alkyl complexes involve platinum(IV) methyl complexes, " and examples of methylplatinum(rV) complexes that undergo reductive elimination are shown in Equation 8.48. These reactions occur by a pathway involving dissociation of the anion to form a cationic Pt(IV) intermediate and subsequent nucleophilic attack of the anion on the methyl... 

A cationic trifluoromethylplatinum solvent complex reacts with phenylacetylene and 2-chloroethanol to form a neutral /3-alkoxyalkenylplatinum complex 149 via nucleophilic attack of the alcohol to the initially formed alkynyl complex (Equation (34)) The reaction is unique to the complex having an electron-withdrawing GF3 ligand, and a cationic methylplatinum(ii) complex with a similar structure reacts with phenylacetylide to yield the cationic complex with a carbene ligand (150, Equation (35)). 

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