Mononuclear (η6-arene)ruthenium(II) and (η5-penthamethylcyclopentadienyl)rhodium(III) and binuclear ruthenium(II)-platinum(II) and ruthenium(II)-rhodium(I) complexes containing 2-(diphenylphosphino)pyridine

Article abstract of DOI:10.1016/0022-328X(94)24773-C

The isoelectronic complexes <(η⁶-C6H6)Ru(Ph2PPy)Cl2> (1) and <(η⁵-C5Me5)Rh(Ph2PPy)Cl2> (3) in which 2-(diphenylphosphino)pyridine (Ph2PPy) is P-monodentate, have been obtained by treating the complexes <<(η⁶-C6H6)RuCl2>2>, and <<(η⁵-C5Me5)RhCl2>2>, respectively, with Ph2PPy 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 <(η⁶-C6H6)Ru(Ph2PPy)Cl>PF6 (2) amd <(η⁵-C5Me5)Rh(Ph2PPy)Cl>PF6 (4) in which the Ph2PPy is chelating, have been obtained.The reaction of <(η⁶-C6H6)Ru(Ph2PPy)Cl2> (1) with cis- in CH2Cl2 gives the ionic binuclear complex <(η⁶-C6H6)Ru(Ph2PPy)(μ-Cl)Pt(DMSO)Cl2>Cl (5a) which was also obtained as the ^- salt, 5b.IR, 1H and 31P<1H> NMR spectra support structures for 5a and 5b with the Ph2PPy 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-tBuNC)2Cl2> in CH2Cl2 at room temperature, the reagents were recovered unchanged after 7 h.The reactions of <(η⁵-C5Me5)Rh(Ph2PPy)Cl2> (3) with cis-tBuNC)2Cl2> and cis- afford the known cis-tBuNC)(Ph2PPy)Cl2> and cis-, together with <<(η⁵-C5Me5)RhCl2>2>.The reaction of <<(C8H12)RuCl2>n> with <(η⁵-C5H5)Rh(CO)(Ph2PPy)> in CH2Cl2 in the molar ratio 1:1, is very complex.We have separated <(C8H12)RuCl((μ-Cl)(μ-Ph2PPy)Rh(η⁵-C5H5)> (6) by chromatography column.The bridging Ph2PPy is P-bonded to the rhodium(I).On allowing CH2Cl2 solution of 6 to stand, crystals of the rhodium(III) complex <(η⁵-C5H5)RhCl2(Ph2PPy)> (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. Keywords: Ruthenium; Platinum; Rhodium; Binuclear complexes; X-ray structure; Bridging ligand