1,6-Diene Complexes of Palladium(0) and Platinum(0):  Highly Reactive Sources for the Naked Metals and [L−M⁰] Fragments

Abstract

The complexes (cod)MCl 2 (M ) Pd, Pt; cod ) cis,cis-1,5-cyclooctadiene) react with Li 2 (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 Pd 0 and Pt 0 compounds Pd 2 (C 7 H 12 ) 3 (1), Pd 2 (C 6 H 10 O) 3 ‚C 6 H 10 O (2′; 2: Pd 2 (C 6 H 10 O) 3 ), Pd 2 (dvds) 3 (3), and Pt 2 (C 7 H 12 ) 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 (C 2 H 4 )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 η 2 -alkene (5-12) or η 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 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 Pd 0 and Pt 0 . The corresponding L-M(1,6-diene) complexes are equally reactive precursor compounds for the generation of [L-M 0 ] fragments in solution, which for M ) Pd are available otherwise only with difficulty. The results are significant for the operation of naked Pd 0 and L-Pd 0 catalysts in homogeneous catalysis.

The Clusters [Ma(ECp*)b] (M=Pd, Pt; E=Al, Ga, In): Structures, Fluxionality, and Ligand Exchange Reactions

“…The final H 2 O content in all solvents used was checked by Karl-Fischer-titration and did not exceed 5 ppm. [Pd 2 (dvds) 3 ], [30] AlCp*, [31,32] and GaCp* [33] were prepared according to recent literature methods. Elemental analyses were performed by the Microanalytical Laboratory of the Ruhr-Universität Bochum.…”

Pt0 and Pd0 Olefin Complexes of the Metalloid N‐Heterocyclic Carbene Analogues [EI(ddp)] (ddp=2‐{(2,6‐diisopropylphenyl)amino}‐4‐{(2,6‐diisopropylphenyl)imino}‐2‐pentene; E=Al, Ga): Ligand Substitution, HH and SiH Bond Activation, and Cluster Formation

“…The final H 2 O content in all solvents was checked by Karl-Fischer titration and did not exceed 5 ppm. [PtA C H T U N G T R E N N U N G (cod) 2 ], [34] [Pd 2 A C H T U N G T R E N N U N G (dvds) 3 ], [27] [GaA C H T U N G T R E N N U N G (ddp)], [6] and [Al-A C H T U N G T R E N N U N G (ddp)] [5] were prepared according to literature methods. Elemental analyses were performed by the Microanalytical Laboratory of the Ruhr-Universität Bochum.…”

“…Its molecular structure ( Figure 1) exhibits a coplanar arrange- [27] whereas the C=C bond lengths are considerably longer (1.404 (7) (1) ) is slightly longer than in the monomeric com-…”

Synthesis and Crystal Structures of Zerovalent Platinum η2-Fumarate Bis(norbornene) Complexes and Their Application as Hydrosilylation Catalysts

“…The synthesis of such complexes usually starts from [Pt(cyclooctadiene) 2 ] 1,2 or one of the numerous other platinum(0)-alkene complexes such as 3 ], 2 [Pt(η 2 -norbornene) 3 ], 3,4 [Pt(η 2 -styrene) 3 ], 5 [Pt(dibenzylideneacetone) 2 ], 6 [Pt 2 (η 4 -divinyltetramethyldisiloxane) 2 (µ-η 4 -divinyltetramethyldisiloxane)], 7 and [Pt 2 (η 4 -hepta-1,6-diene) 2 (µ-η 4 -hepta-1,6-diene)]. 8 Over the years, many other platinum(0)-alkene complexes have been reported, including a large amount of "mixed" alkene complexes, such as [Pt(η 4 -cyclooctadiene)(η 2 -dimethyl fumarate)], 9,10 [Pt(η 2 -tetrafluoroethene)(η 2 -norbornene) 2 ], 11 [Pt(η 2 -2-methylnaphthoquinone)(η 2 -norbornene) 2 ], 12 and [Pt 2 (µ-η 4 -p-benzoquinone) 2 (η 2 -norbornene) 2 ]. 13 Zerovalent platinum complexes are frequently used as catalysts for the hydrosilylation of unsaturated carbon-carbon bonds (Scheme 1).…”