1,6-diene complexes of palladium(0) and platinum(0): Highly reactive sources for the naked metals and [L-M-0] fragments

The complexes (cod)MCl2 (M = Pd, Pt; cod = cis,cis-1,5-cyclooctadiene) reac t with Li-2(cot) (cot cyclooctatetraene) in a 1,6-diene/diethyl ether mixtu re (1,6-diene = hepta-1,6-diene, diallyl ether, dvds (1,3-divinyl-1,1,3,3-t etramethyldisiloxane)) to afford the isolated homoleptic dinuclear Pd-0 and Pt-0 compounds Pd-2(C7H12)(3) (1), Pd-2(C6H10O)(3). C6H10O (2', 2: Pd-2(C6 H10O)(3)), Pd-2(dvds)(3) (3), and Pt-2(C7H12)(3) (4) When 1-4 are treated w ith additional 1,6-diene the equally homoleptic but mononuclear derivatives of type M(1,6-diene)(2) (5-8) and with ethene the mixed alkene complexes ( C2H4)M(1,6-diene) (9-12) are obtained in solution. Complexes 1-12 react wit h donor ligands such as phosphanes, phosphites, or (BuNC)-Bu-t to give isol ated complexes of types L-M(1,6-diene) (13-41), which have also been prepar ed by other routes. in all complexes the metal centers are TP-3 coordinated : complexes 1-4 contain chelating and bridging 1,6-diene ligands, whereas t he other complexes contain a chelating 1,6-diene ligand and an eta(2)-alken e (5-12) or eta(1)-donor ligand (13-41). Of the studied 1,6-diene complexes the hepta-1,6-diene derivatives are most reactive, while the diallyl ether complexes are often more convenient to handle. The readily isolable dinucl ear hepta-1,6-diene and diallyl ether complexes 1, 2', and 4, and their mon onuclear pure olefin derivatives are among the most reactive sources for na ked Pd-0 and Pt-0. The corresponding L-M(1,G-diene) complexes are equally r eactive precursor compounds for the generation of [L-M-0] fragments in solu tion, which for M = Pd are available otherwise only with difficulty. The re sults are significant for the operation of naked Pd-0 and L-Pd-0 catalysts in homogeneous catalysis.