164019-42-5Relevant articles and documents
Reactivity studies of cationic palladium(II) phosphine carboxylate complexes with lewis bases: Substitution versus cyclometalation
Thirupathi, Natesan,Amoroso, Dino,Bell, Andrew,Protasiewicz, John D.
, p. 3157 - 3166 (2008/10/09)
Two classes of cationic palladium(II) phosphine carboxylate complexes were isolated and characterized. Reactions of trans-[(R3P) 2Pd(O2CR′)2] (1) with [Li(OEt 2)2.5][B(C6F5)4] in MeCN led to carboxylate abstraction and formation of trans-[(R3P) 2Pd(O2CR′)(MeCN)][B(C6F5) 4] (2) in good to excellent yields. On the other hand, carboxylate abstraction reactions of 1 with [Me2(H)NPh][B(C6F 5)4] or p-toluenesulfonic acid (HOTs·H 2O) in CH2Cl2 furnished the palladium cations [(R3P)2Pd(κ2-O,O-O2CR′)] + (3). The reactions of 2 and 3 with Lewis bases were found to be different in some cases. For example, reactions of 2 with pyridine furnished the simple products of acetonitrile substitution, trans-[(R3P) 2Pd(O2CR′)(py)][B(C6F5) 4]. In contrast, the reaction of 3e (R = iPr, R′ = CH3) with CD3CN in the presence of excess sodium carbonate yielded a material derived from cyclometalation of one of the iPr arms of iPr3P ligand. New complexes were characterized by elemental analyses and NMR (1H, 13C, and 31P) spectroscopic methods and in two cases by single-crystal X-ray structural methods.
Indirect formation of carboxylic acids via anhydrides in the palladium-catalyzed hydroxycarbonylation of aromatic halides
Grushin, Vladimir V.,Alper, Howard
, p. 4305 - 4315 (2007/10/02)
The carbonylation of [(Ph3P)2Pd2Ph2(μ-OH)2] (2) in the presence of PhI results in the quantitative formation of benzoic anhydride and [(Ph3P)2Pd2(PhCO)2(μ-I) 2] (3). This transformation contributes to some extent to the production of benzoic acid from haloarenes, CO, and alkali, catalyzed by [(Ph3P)2PdCl2], the latter being converted to 2 under the reaction conditions. Phenyl- and benzoylpalladium benzoates are likely key intermediates in the indirect formation of the acid, via the anhydride, by the carbonylation of 2. One such complex, [L2Pd(Ph)(PhCOO)] (5, L = Cy3P), was isolated from the carbonylation of [(Cy3P)2Pd2Ph2(μ-OH)2] (4) in hexane. The related complexes, [L2Pd2Ph2(μ-PhCOO)2] (6, L = PPh3; 7,L = PCy3), were prepared from benzoic acid and hydroxo complexes 2 and 4, respectively. Treatment of 6 and 7 with the corresponding phosphine afforded [L2Pd(Ph)(PhCOO)] (8, L = PPh3; 5,L = PCy3). When 6-8 were reacted with CO in benzene, benzoic anhydride was readily formed, whereas in the case of 5 both carbonylation and reductive elimination were sluggish. Crystallographic data for 6 (1:2 chloroform solvate): space group Pccn, a = 22.499(4) A?, b = 10.992(3) A?, c = 24.514(6) A?, V = 6062.4(23) A?3, Z = 4, R = 0.056, and Rw = 0.038.
