Date: 06 Sep 2013

Platinum Phosphinito Catalysts for Nitrile Hydration

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Abstract

The reaction of PEt2OH with K2PtCl4 yields [PtCl{(PEt2O)2H}]2 (2). The X-ray crystal structure of 2 shows that the two chloride ligands bridge the two Pt atoms. The structure is unusual in that the PtCl2Pt unit is bent, which is the first example of a platinum phosphinito chloride-bridged dimer that is bent. Dimer 2 is a poor catalyst for the hydration of acetonitrile (and presumably other nitriles). Likewise, the monomeric catalyst that results from the reaction of 2 with sodium hydroxide is not a good hydration catalyst. In an attempt to form a more reactive monomeric catalyst, PtCl(PMe2OH){(PMe2O)2H} (1) was reacted with sodium hydroxide. This reaction resulted in the formation of two species, tentatively characterized as Na[PtCl(PMe2O){(PMe2O)2H}] (5) and Na[PtCl(OH){(PMe2O)2H}] (6). Complexes 5 and 6 could not be separated. However, the mixture of the two complexes quickly hydrated acetonitrile. The catalyst mixture of 5 and 6 was efficiently poisoned by cyanide, which prevented its use as a catalyst for the hydration of cyanohydrins.