Synthesis and reactivity of [Ru(Cp*)(L)(MeCN)2][PF6] (L = Ph2POMe or Ph2P-o-tolyl) and {Ru(Cp*)[Ph2PCH2C(tBu)=O](MeCN)}[PF6] complexes, their involvement as catalyst precursors for regioselective allylic substitution reactions and related [Ru(Cp*)Cl(Ph2POMe)(RCHCHCH2)][PF6] η3-allyl ruthenium(IV) intermediates

The synthesis of the new complexes [Ru(Cp*)(L)(MeCN)(2)]-[PF6] (L = Ph2POMe or Ph2P-O-tolyl) and {Ru(Cp*)-[Ph2PCH2C(tbu)=O](MeCN)}[PF6] (2a-c) is achieved starting from [Ru(Cp*)(MeCN)(3)][PF6]. The acetonitrile ligands in complexes 2a-c are labile, as emphasised by the easy formation of {Ru(Cp*)(CO)(2)[Ph2PCH2C(=O)tBu]}[PF6] (3). The keto-phosphane is used as a tool to convert 3 into {Ru(Cp*)-(CO)[Ph2PCH2C(tBu)=O]}[PF6] (5). Complex 5 reacts with 1,1-diphenyl-2-propyn-1-ol in methanol as solvent to afford the vinyl-carbene complex {Ru(Cp*)(CO)[=C(OMe)-CH=CPh2][Ph(2)pCH(2)C(=O)tBu]}[PF6]. The new eta(3)-allyl ruthenium(iv) derivatives [Ru(Cp*)Cl(Ph2POMe)(CH2CMeCH2)]-[PF6] and [Ru(Cp*)Cl(Ph2POMe)(RCHCHCH2)][PF6] (R = Me; nPr, 8d; or Ph, Be) are obtained by reacting 2a with the appropriate allylic halide. The X-ray crystal structure determination of the compounds 8d and Be disclosed an endotrans-RCHCHCH2 eta(3)-allyl ligand. The formation of branched allyl aryl ethers is regioselectively favoured when complexes 2a-c are involved as catalyst precursors for the etherification of cinnamyl chloride, chlorohexene and 3-chloro-4-phenylbut-1-ene with phenol, p-methoxyphenol, cresols and (o or p)-chlorophenols, in the presence of K2CO3((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).