LAUSR

Abstract Reactions of secondary phosphines HPR1R2 [R1 = R2 = p-MeOC6H4 (b), p-CF3C6H4 (c), mesityl (Mes, d) or 1-adamantyl (Ad, e); R1 = t-Bu, R2 = Ph (f)] with cyclopalladated complexes (CPCs) derived from N,N-dimethylbenzylamine (1), l -fenchone methyloxime (3), (S)-N,N-dimethylbenzylamine (9), and (S)-di-2,4-tert-butyloxazoline (11) were studied. Phosphination of the cyclopalladated ligands in complexes 1 and 3 was observed using either 4.5:1 or 9:1 molar ratios of HPAr2 (b,c) to CPC in the presence of 9 equiv. Cs2CO3. The corresponding N,P ligands 2b,c and 4b,c were isolated in 44–59% yields. Reactions of the sterically hindered HPMes2 with CPCs 1 and 3 provided the phosphination product, 4d′, only for the latter complex (32% yield). Attempts to synthesize N,P ligands with HPAd2 were unsuccessful with either palladacycle. Major products of the reactions of complexes 1 and 3 with bulky HPMes2 and HPAd2 were either rare mononuclear complexes 5d,e (up to 90%) and 7d,e (81 and 86%) with an ancillary secondary phosphine ligand or dinuclear monophosphido, monochloro-bridged complexes 6d (98%) and 8d,e (69% and 66%) depending on the HPR2:CPC molar ratio used. Enantiopure CPC 3 reacted with racemic HPt-BuPh to give a single diastereomer of the phosphination product 4f in 12% yield. Attempts to use the racemic phosphine in transformations with two other enantiopure CPCs, 9 and 11, to form a C Pt-BuPh bond were unsuccessful. Instead, reactions of these two complexes with racemic HPt-BuPh provided monophosphido, monochloro-bridged CPCs 11f and 13f in 32 and 76% yield, respectively. Analysis of 1H, 13C{1H} and 31P{1H} NMR data of all new Pd(II) complexes and N,P ligands is provided. An X-ray crystallographic study of complex 7d proved its trans-N,P geometry.