Synthetic, Spectroscopic and Structural Studies of the Rhenium(I) Dicarbonyl Complexes of Phosphite, Phosphonite, and Phosphinite Ligands: cis, mer ‐[ReBr(CO) 2 {PPh 3‐n (OR) n } 3 ] (R = Me, Et; n = 1—3)

The reaction of [ReBr(CO) 5 ] with phosphite and phosphonite ligands in toluene yielded cis, mer ‐[ReBr(CO) 2 L 3 ] ( 2 : L = P(OMe) 3 2a : P(OEt) 3 2b : PPh(OMe) 2 2c : PPh(OEt) 2 2d ). Compounds 2c and 2d were also obtained, as were the phosphinite complexes 2e [L = PPh 2 (OMe)] and 2f [L = PPh 2 (OEt)], by reaction of the corresponding phosphorus ligand with trans, mer ‐[ReBr(CO) 3 L 2 ]. Compounds 2 were all characterized by elemental analysis, mass spectrometry and NMR spectroscopy, and the structures of 2b , 2c and 2d were determined by X‐ray diffractometry. Compounds 2a‐d are stable in chloroform and dichloromethane, but 2e and 2f are transformed into the corresponding trans, mer ‐[ReBr(CO) 3 L 2 ] complexes by a reaction for which a partial mechanism is put forward.