Oxidative addition of iodo-acetonitrile and of elemental halogens to [Pt3(μ-CO)3(PCy3)3]

Dalton Transactions Pub Date: 2004-11-30 DOI: 10.1039/B415311A

Abstract

The reaction of [Pt3(μ-CO)3(PCy3)3] (1) with one mole-equivalent of iodo-acetonitrile was quantitative at ?70 °C giving the oxidative addition product [Pt3(μ-CO)3(PCy3)3(I)(CH2CN)] (2). Fragmentation of 2 was observed in solution giving [Pt2I(CH2CN)(CO)2(PCy3)2] (3) which is the major product at room temperature if the starting cluster/reactant ratio is equal to or less than 1 to 1.5. Dimer 3 decomposes slowly in solution giving [Pt2I2(CO)2(PCy3)2] ( 4a) and succinonitrile. Monomer [PtI(CH2CN)(CO)(PCy3)] was the final product of the reaction when using excess of iodo-acetonitrile. The reactions of 1 with one mole-equivalent of halogens X2 gave the new 44-electron clusters [Pt3X(μ-CO)2(μ-X)(PCy3)3] (X = I2 ( 7a) or Br2 ( 7b)) by oxidative addition followed by substitution of CO by X?. Fragmentation of 7a and 7b took place in solution when using one and a half mole-equivalents of X2 giving dimers 4a and [Pt2Br2(CO)2(PCy3)2] ( 4b) as well as [Pt2X2(μ-X)2(CO)2(PCy3)2]. Monomers cis-[PtX2(CO)(PCy3)] were the final products of the reaction of 1 with excess of halogens. Insertion of SnCl2 was observed into the Pt–Pt bond but not into the Pt–X bond, when equimolar amounts of SnCl2·2H2O were added to a solution of 4a or its chloro-analogue giving [Pt2X2(μ-SnCl2)(CO)2(PCy3)2]. The Pt(I) dimers have unusually small J(Pt–Pt) values as observed by 195Pt NMR and calculated by DFT. These values showed periodic changes comparing 4a and its analogues with other halides and mixed halide dimers.

Graphical abstract: Oxidative addition of iodo-acetonitrile and of elemental halogens to [Pt3(μ-CO)3(PCy3)3]
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