Dative ligands

Scheme 3 summarizes the reductive elimination chemistry of arylpalladium amides. Arylpalladium amido complexes containing PPh3 as the dative ligand were stable enough to isolate, and... 

More recently, reductive elimination of aryl ethers has been reported from complexes that lack the activating substituent on the palladium-bound aryl group (Equation (55)). These complexes contain sterically hindered phosphine ligands, and these results demonstrate how steric effects of the dative ligand can overcome the electronic constraints of the reaction.112,113 Reductive elimination of oxygen heterocycles upon oxidation of nickel oxametallacycles has also been reported, but yields of the organic product were lower than they were for oxidatively induced reductive eliminations of alkylamines from nickel(II) mentioned above 215-217... 

Thus, (4.9a) gives the general condition for an idealized covalently bonded closed-shell Lewis-like duodectet structure (4.9b) with no formal charge on the central metal atom. (The more general conditions for coordinative [dative] ligands and other departures from the idealized Lewis-like formula will be discussed below.)... 

H. E. Bryndza, P. J. Domaille, R. A. Paciello, J. E. Bercaw. Kinetics and Mechanism of Phosphine Exchange for Rutheniumill) Complexes in the Series (r 5-CsMes)(PMeo,)2RuX. Ancillary Ligand Effects on Dative Ligand Dissociation. Organometallics 1989, 8, 379-385. 

The mechanism of reversible (5-hydrogen elimination from square planar lr(l) alkoxide complexes with labile dative ligands, followed by associahve displacement of the coordinated ketone or aldehyde by incoming phosphine, which can be implied in TH reactions, was proposed by Hartwig and coworkers [36]. 

Recently, it was also shown [74] that pentamethylcyclopentadienyl rhodium and iridium complexes with labile dative ligands catalyze the borylation of alkanes at the terminal position under thermal conditions (Scheme 9). It was proposed that Ir(V) and Rh(V) boryl complexes act as intermediates in these reactions. Reaction of Cp IrH4 with HBpin gives Cp Ir(Bpin)(H)3 and Cp Ir(Bpin)2(H)2. Both of the two Ir(V) boryl complexes react with octane to give octylboronate ester [75], though it is still unclear regarding the role... 

In principle, any organometallic molecule that loses a dative ligand in a photochemical heterolysis reaction is a potential catalyst for this type of polymerization. Other common catalysts are (7 -C6H7)Fe(CO)3 and CpFe(CO)2L (L = various phosphines or other ligands). The former molecule, in particular, is exceptionally reactive. When these molecules are irradiated, an M-CO bond is dissociated the coordinatively unsaturated species thus produced reacts with, for example, an epoxide monomer, and polymerization proceeds via a standard ring-opening pathway. 

Stambuli, J.P., Buhl, M. and Hartwig, J.F. (2002) Synthesis, characterization, and reactivity of monomeric, arylpalladium halide complexes with a hindered phosphine as the only dative ligand. J. Am. Chem. Soc., 124, 9346-7. 

Figure 1.15. The top lobes of the n-orbltals of Cp vs. three dative ligands.

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