Dinuclear Palladium(II) and Platinum(II) Complexes of a Readily Accessible Bicyclic Diphosphane

The one-step synthesis (33 % isolated yield) of a novel bicyclic diphosphane, [P(CH2)2NC6H4(4-NMe2)]2, P−P(NMe2), from the reaction [P(CH2OH)4]Cl and H2NC6H4(4-NMe2) in methanol is described. Surprisingly, P−P(NMe2) displays excellent air/solution stability (towards H2O, CH3OH) can also function efficiently as bridging ligand. Hence with [Pd(μ−Cl)(η3-allyl)]2 (η3-allyl=C3H5, C4H7) or [Pd(μ−Cl)(κ2−C9H12N)]2 affords singly-bridged complexes {Pd(Cl)(η3-allyl)}2{μ-P−P(NMe2)} 1 a/1 b {Pd(Cl)(κ2−C9H12N)}2{μ-P−P(NMe2)} c whereas treatment [MX2(η4-cod)] (M=Pd, Pt; X=Cl, Br, I, Me; η4-cod=cycloocta-1,5-diene) gave (MX2)2{μ-P−P(NMe2)}2 2 a–e high yields. Protonation a–d HBF4 ⋅ OEt2 corresponding dimethylammonium salts 3 a–d. Single crystal X-ray studies have been undertaken on b, a, 2CDCl3, d, e, 12CD3CN 12CD3CN. P−P bond lengths free/coordinated remain similar across all compounds studied here no M ⋅⋅⋅ contacts were observed within planar M2P4 ring. In a/3 BF4− anion unique secondary interaction inorganic six-membered core.