Reactivity of dinuclear platina-beta-diketones toward phosphines and pyridines: Formation of mononuclear platina-beta-diketones and acyl(chloro)platinum(II) complexes

Dinuclear platina-beta-diketones [Pt-2{(COR)(2)H}(2)(mu-Cl)(2)] (R = Me (la ), Et (Ib)) react with phosphines (PPh3, Ph2P(CH2)(n)PPh2, n = 1-3) and tri phenylarsine to form acylplatinum(II) complexes as well as acetaldehyde and propionaldehyde, respectively. Reaction of 1 with 4 equiv of PPh3 and AsPh 3 leads to trans-[PtCl(COR)L-2] (L = PPh3 (4), AsPh3 (5); R = Me (a), Et (b )). Reaction of la with PPh3 in a 1:2 molar ratio results in formation of c arbonyl(methyl)platinum complexes [PtCl(Me)(CO)(PPb3)] (11), Cationic A-fra me complexes [Pt-2(COR)(2)(mu-Cl)(mu-dppm)(2)]Cl (R = Me (6a), Et (6b)) wer e formed in reactions of 1 with 2 equiv of Ph2PCH2PPh2 (dppm), Treatment of la with Ph2P(CH2)(2)PPh2 (dppe) and Ph2P(CH2)(3)PPh2 (dppp) yields complex es [PtCl(COMe){Ph2P(CH2)(n)PPh2}] (n = 2 (7), 3 (8)). However, at low tempe ratures (-30 degrees C) reactions of la with dppe and dppp afford mononucle ar cationic platina-beta-diketones [Pt{(COMe)(2)H}(Ph2P(CH2)(n)PPh2)]Cl (n = 2 (9a), 3 (10)). The reaction of [Pt-2{(COMe)(2)H}(2)(mu-Cl)(2)] (1a) wit h pyridine (py) or quinoline (quin) results in cleavage of the Pt-Cl-Pt bri dges, yielding mononuclear neutral platina-beta-diketones [PtCl{(COMe)(2)H} L] (L = py (13a), quin (13b)). In the solid state complex 13b reveals a non planar arrangement of the platina-beta-diketone unit with a strong hydrogen bond (O ... O 2.419(8) Angstrom). From all these findings the mechanism of the aldehyde formation in the reactions of platina-beta-diketones 1 with L (PPh3, AsPh3) and LL (dppm, dppe, dppp) is deduced.