Platinum carbonyl cation

In a three-component reaction, a cationic platinum isocyanide complex [(Ph3P)2Pt(CNR)Cl][BF4] is reacted with a /3-bromoamine and butyl lithium to give an imidazoldin-2-ylidene complex.This transformation can be a two-component reaction if the isocyanide ligand contains already the necessary amine functionality. This was shown for chromium, molybdenum, tungsten, and rhenium carbonyls. 

Anionic and Cationic Carbonyls. The polarographic behaviour of Et N-[Fe(CO)3NO] at dropping mercury and stationary platinum electrodes has been studied. Two anodic waves and one cathodic wave were observed and the following reactions were suggested ... 

The platinum-catalysed intramolecular domino annulation reaction of o-alkynylben-zaldehydes has been described as a versatile approach to naphthalenes with annulated carbocycles or heterocycles of various sizes (Scheme 32).94 A plausible mechanism for the platinum(II)-catalysed annulation reaction shows that the double annulation process most probably proceeds through the benzopyrylium cation (117), which results from the nucleophilic attack of the carbonyl oxygen at the alkyne, activated by the Lewis-acidic platinum salt. A subsequent intramolecular Huisgen-type 3 + 2-cycloaddition of the second alkyne is assumed to generate intermediate (118). Rearrangement to (119) and the formal 4 + 2-cycloaddition product (118) leads to the aromatized final (116), liberating the active catalyst. In the case of FeCl3 as the Lewis acid, we assume that intermediate (118) is oxidatively transformed to (121). 

Recent studies indicate the reaction of platina-/3-diketone with bipyridines via oxidative addition yields the diacyl hydrido Pt(IV) complex. Further ligand abstraction may result in H bond bridged dimer and a double-deck dimer through Pt Pt interaction (Scheme 17). On the other hand, the prototype of unsupported cis- diacyl platinum(II) species was obtained either via nucleophilic addition to cationic acyl carbonyl complexes or CO insertion into a trans acyl alkyl complex (Scheme 18). In the latter process for propionyl methyl or acetyl ethyl complex. 

Alkoxycarbonyl-platinum complexes form in reactions between a cationic metal-carbonyl complex and an alcohol ... 

Carbonylation of the isomeric cationic solvated complexes of platinum(II) C and D [the corresponding palladium(II) species react at a much faster rate] proceeds via an alkyl migration mechanism in a study based on NMR detection of the intermediates. This conclusion is in agreement with the available data in the literature kinetic data should, however, complement the information concerning the palladium(II) and plati-num(II) systems. 

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