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)(5)Br (in the presence of Et3N) and (PhCN)(2)PdCl2 these ligands afforded kappa(3)-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 kappa(3)-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. (C) 2013 Elsevier Ltd. All rights reserved.