252008-10-9Relevant articles and documents
1,6-Diene complexes of palladium(0) and platinum(0): Highly reactive sources for the naked metals and [L-M0] fragments
Krause, Jochen,Cestaric, Günter,Haack, Karl-Josef,Seevogel, Klaus,Storm, Werner,P?rschke, Klaus-Richard
, p. 9807 - 9823 (2007/10/03)
The complexes (cod)MCl2 (M = Pd, Pt; cod = cis,cis-1,5-cyclooctadiene) react with Li2(cot) (cot = cyclooctatetraene) in a 1,6-diene/diethyl ether mixture (1,6-diene = hepta-1,6-diene, diallyl ether, dvds (1,3-divinyl- 1,1,3,3-tetramethyldisiloxane)) to afford the isolated homoleptic dinuclear Pd0 and Pt0 compounds Pd2(C7H12)3 (1), Pd2(C6H10O)3·C6H10O (2'; 2: Pd2(C6H10O)3), Pd2(dvds)3 (3), and Pt2(C7H12)3 (4). When 1-4 are treated with 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 with donor ligands such as phosphanes, phosphites, or (t)BuNC to give isolated complexes of types L-M(1,6-diene) (13-41), which have also been prepared 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 the other complexes contain a chelating 1,6-diene ligand and an η2-alkene (5-12) or η1-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 dinuclear hepta-1,6-diene and diallyl ether complexes 1, 2', and 4, and their mononuclear pure olefin derivatives are among the most reactive sources for naked Pd0 and Pt0. The corresponding L-M(1,6-diene) complexes are equally reactive precursor compounds for the generation of [L-M0] fragments in solution, which for M =Pd are available otherwise only with difficulty. The results are significant for the operation of naked Pd0 and L-Pd0 catalysts in homogeneous catalysis.
