Synthesis and coordination of the bifunctionalized ylides Ph2P(CH2)n(Ph)2PCHCOOMe (n = 1, 2) and ketenylidene Ph2P(CH2)2(Ph)2PCCO to Pd and Pt complexes

In this paper it is reported the synthesis of the phosphonium salts [Ph2P(CH2)n(Ph)2PCH2COOMe]Br (n = 1 (1), 2 (2)) and [Ph2P(CH2COOMe)(CH2)n(Ph)2PCH2COOMe]Br2 (n = 3 (3)) derived from the reactions of the diphosphines dppm, dppe and dppp with methyl bromoacetate. By reaction of the monophosphonium salt of dppm and dppe with the strong base Na[N(SiMe3)2] the corresponding carbonyl stabilized ylides Ph2P(CH2)n(Ph)2PCHCOOMe (n = 1 (4), 2 (5)) were obtained. The Ph2P(CH2)2(Ph)2PCHCOOMe (5) ylide was reacted with Pd(II) and Pt(II) substrates. From these reactions were isolated exclusively complexes in which the ylide was chelated to the metal through the free phosphine group and the ylidic carbon atom. A further reaction of the Ph2P(CH2)2(Ph)2PCHCOOMe (5) ylide with 1.5 equiv. of Na[N(SiMe3)2] gives the bifunctionalized ketenylidene Ph2P(CH2)2(Ph)2PCCO (6) system. This cumulenic ylide reacts with Pt(II) complexes to form a chelated derivative in which IR and NMR spectra suggest the breaking of the CC bond of the –CCO group.