RHODIUM(I) COMPLEXES OF THE DPPN LIGAND, 3,6-BIS(2'-PYRIDYL)PYRIDAZINE AND X-RAY STRUCTURE OF [RH(CO)(DPPN)(PPH3)](PF6)

The reaction of the 3,6-bis (2'-pyridyl)pyridazine(dppn) ligand, with one and two equivalents of [Rh(CO)(2)S-n](PF6), (s = THF), yields resp ectively the mononuclear complex [Rh(CO)(2)(dppn)] (PF6) 1 and the bin uclear complex [Rh-2(CO)(4)(dppn)] (PF6)(2) 3. Furthermore, the reacti on of 1 with PPh3 results in a substitution reaction to give [Rh(CO)(d ppn)(PPh3)(2)] (PF6) 2. The unsaturated complex 3 reacts with the mono dentate phosphine PPh3 to yield a mixture of the known compound [Rh(CO )(2)(PPh3)(2)] (PF6) and of the mononuclear [Rh(CO)(dppn)(PPh3)](PF6) 4, the crystal structure of which was established by X-ray diffraction . Moreover, 3 reacts with the bis(diphenylphosphino)methane(dppm) liga nd in a 1:2 ratio to form the binuclear A-frame complex [Rh-2(CO)(2)(d ppn) (mu-dppm)(2)](PF6)(2) 5. However, the reaction of 3 with excess d ppm (1:4 ratio) gives the known complex [Rh(CO)(dppm)(2)] (PF6) 6. (C) 1998 Elsevier Science Ltd. All rights reserved.