MONONUCLEAR(MU(6)-ARENE)RUTHENIUM(II) AND (ETA(5)-PENTAMETHYLCYCLOPENTADIENYL)RHODIUM(III) AND BINUCLEAR RUTHENIUM(II) PLATINUM(II) AND RUTHENIUM(II) RHODIUM(I) COMPLEXES CONTAINING 2-(DIPHENYLPHOSPHINO)PYRIDINE

The isoelectronic complexes [(eta(6)-C6H6)Ru(Ph(2)PPy)Cl-2] (1) and [(eta(5)-C(5)Me(5))Rh(Ph(2)PPy)Cl-2] (3) in which 2-(diphenylphosphino)pyridine (Ph(2)PPy) is P-monodentate, have been obtained by treating the complexes [{(eta(6)-C6H6)RuCl2}(2)], and [{(eta(5)-C(5)Me(5))RhCl2}(2)], respectively, with Ph(2)PPy in the molar ratio 1:1. Coordination of the pyridine nitrogen atom to metal in 1 and 3 has been achieved by removing one chloride with AgPF6. By this route the cationic complexes [(eta(6)-C6H6)Ru(Ph(2)PPy)Cl]PF6 (2) and [(eta(5)-C(5)Me(5))Rh(Ph(2)PPy)Cl]PF6 (4) in which the Ph(2)PPy is chelating, have been obtained. The reaction of [(eta(6)- C6H6)Ru(Ph(2)PPy)Cl-2] (1) with cis-[Pt(DMSO)(2)Cl-2] in CH2Cl2 gives the ionic binuclear complex [(eta(6)-C6H6)Ru(Ph(2)PPy)(mu-Cl)Pt(DMSO)Cl-2]Cl (5a) which was also obtained as the [PF6](-) salt, 5b. IR, H-1 and (31)p{H-1} NMR spectra support structures for 5a and 5b with the Ph(2)PPy chelated to ruthenium(II) and a chloride bridging to platinum(II). The DMSO is S-bonded and the geometry at platinum(II) is cis. Upon attempted reaction of 1 with cis-[Pd((t)BuNC)(2)Cl-2] in CH2Cl2 at room temperature, the reagents were recovered unchanged after 7 h. The reactions of [(eta(5)-C(5)Me(5))Rh(Ph(2)PPy)Cl-2] (3) with cis-[Pd((t)BuNC)(2)Cl-2] and cis[Pt(DMSO)(2)Cl-2] afford the known cis-[Pd((t)BuNC)(Ph(2)PPy)Cl-2] and cis-[Pt(DMSO)(Ph(2)PPy)Cl-2], together with [{(eta(5)-C(5)Me(5))RhCl2}(2)]. The reaction of [{(C8H12)RuCl2}(n)] with [(eta(5)-C5H5)Rh(CO)(Ph(2)PPy)] in CH2Cl2 in the molar ratio 1:1, is very complex. We have separated [(C8H12)RuCl((mu-Cl)(mu-Ph(2)PPy)Rh(eta(5)-C5H5)] (6) by chromatography column. The bridging Ph(2)PPy is P-bonded to the rhodium(I). On allowing CH2Cl2 solution of 6 to stand, crystals of the rhodium(III) complex [(eta(5)-C5H5)RhCl2(Ph(2)PPy)] (7) are formed. Probably a very slow intramolecular redox process involving the Ru-II-Rh-I species 6 is responsible of the formation of 7. In the complex, the 2-(diphenylphosphino)pyridine is monodentate, coordinating through phosphorus.