SYNTHESIS AND COORDINATION CHEMISTRY OF A NEW CLASS OF BINUCLEATING LIGANDS - PYRIDYL-SUBSTITUTED DIPHOSPHINES

The syntheses of three new binucleating ligands, (C6H5)(2-C5H4N)P(CH2)nP(C6H5)(2-C5H4N) (n = 1, DPyPM; n = 2, DPyPE; n = 3, DPyPP), are described and their coordination properties have been probed. rac-DPyPM reacts with [Rh(CO)2Cl]2 to produce a binuclear complex DPyPM[Rh(CO)Cl]2, in which the ligand forms three bridges between the two Rh(CO)Cl fragments. The structure of the bis(acetonitrile) solvate (determined by X-ray diffraction) shows two approximately square-planar rhodium centers with a (nonbonded) Rh–Rh distance of 3.093 (1) Å. The meso isomers of DPyPE and DPyPP react with [Rh(CO)2Cl]2 to give [L2Rh2Cl2][Rh(CO)2Cl2]2; the structure of the DPyPP complex was determined by X-ray crystallography. In the complex cation, each rhodium atom is surrounded in an octahedral fashion by two phosphorus atoms of one DPyPP ligand, two pyridyl nitrogens of the second DPyPP, the second rhodium atom (Rh–Rh = 2.651 (3) Å), and a chlorine atom trans to Rh. © 1990, American Chemical Society. All rights reserved.