Synthesis and coordination of the bifunctionalized ylides Ph 2P(CH 2) n(Ph) 2P [dbnd]CHCOOMe ( n = 1, 2) and ketenylidene Ph 2P(CH 2) 2(Ph) 2P [dbnd]C [dbnd]C [dbnd]O to Pd and Pt complexes

Abstract

In this paper it is reported the synthesis of the phosphonium salts [Ph 2P(CH 2) n (Ph) 2PCH 2COOMe]Br ( n = 1 ( 1), 2 ( 2)) and [Ph 2P(CH 2COOMe)(CH 2) n (Ph) 2PCH 2COOMe]Br 2 ( 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(SiMe 3) 2] the corresponding carbonyl stabilized ylides Ph 2P(CH 2) n (Ph) 2P CHCOOMe ( n = 1 ( 4), 2 ( 5)) were obtained. The Ph 2P(CH 2) 2(Ph) 2P CHCOOMe ( 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 Ph 2P(CH 2) 2(Ph) 2P CHCOOMe ( 5) ylide with 1.5 equiv. of Na[N(SiMe 3) 2] gives the bifunctionalized ketenylidene Ph 2P(CH 2) 2(Ph) 2P C C O ( 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 C C bond of the –C C O group.