Arene displacement, C-H activation and acetonitrile insertion reactions enabled by coordination of a functionalized iminophosphorane to a Ru II - p -cymene scaffold.

Reaction of a sterically demanding iminophosphorano-phosphine, Ph 2 PCH 2 Ph 2 PNAr* (here onwards referred to as PCPNAr*; Ar* = 2,6-dibenzhydryl-4-methylphenyl), (1) with [Ru(η 6 - p -cymene)Cl 2 ] 2 yielded three different types of complex, [RuCl 2 {(η 6 - p -cymene)(PCPNAr*)-κ 1 - P }] (2), [RuCl{(P(O)CPNAr*)(κ 2 - N , C )( C -η 6 -arene)}] (3) and [RuCl{(POCPNAr*)(κ 2 - N , C-o )( C -η 6 -arene)}] (4), depending on the reaction conditions via CH activation, tethered η 6 -arene coordination, ortho -metallation or PN bond cleavage/rearrangement reactions. Interestingly, a similar reaction in CH 3 CN in the presence of AgBF 4 resulted in the insertion of CH 3 CN into the PN bond to form a novel metallacycle [Ru(NCMe) 3 {(PC 2 PN(CH 3 )CNAr*)-κ 3 - N , N , P }][BF 4 ] 2 (5) containing 4- and 5-membered rings via an aza-Wittig type reaction. Complex 4 showed very good catalytic activity in the transfer hydrogenation of carbonyl compounds.