Coordination of P(X)-modified (X = O, S) N-aryl-carbamoylmethylphosphine oxides and sulfides with Pd(II) and Re(I) ions: Facile formation of 6,6-membered pincer complexes featuring atropisomerism

Direct acetylation of (thio)phosphorylated anilines 1a,b with in situ generated Ph2P(O)CH2C(O)Cl or sequential treatment of 1a,b with chloroacetyl chloride and Ph2PSNa resulted in novel oligodentate ligands, namely, P(X)-modified carbamoylmethylphosphine oxides (CMPO) and sulfides (CMPS) 2a–d. In reactions with Re(CO)5Br (in the presence of Et3N) and (PhCN)2PdCl2 these ligands afforded κ3-XNY (X,Y = O,S) Re(I) (4a,d) and Pd(II) (6b–d) pincer complexes with two fused six-membered metallocycles, owing to ready metallation at the amide nitrogen atom. In the absence of a base, the interaction of 2a with the same rhenium precursor yielded ten-membered κ3-OO metallocycle 5 with Re(I) ion coordinated only by phosphoryl groups. According to the NMR spectroscopy data, the complexes obtained form stable atropisomers in solution at room temperature. The solid state structures of compounds 2a,b and resulting metallocycles were characterized by X-ray crystallography.

P(X)-modified (X = O, S) CMPO(S) readily yield κ3-ONO, SNO, and SNS Re(I) and Pd(II) pincer complexes with two fused six-membered metallocycles, forming in solution at room temperature stable atropisomers.Figure optionsDownload as PowerPoint slide