Synthesis employing oxidative insertion of palladium atoms into aryl, alkyl, and acyl carbon-halogen bonds. Properties of and phosphine trapping of the nonligand stabilizer RPdX and PCOPdX intermediates

Abstract

17) A complex of stoichiometry MnCp2(C4H80)2 (C4HsO is tetrahydrofuran) (18) M. F. Rettig and R. S. Drago, J. Amer. Chem. SOC., 91, 1361 (1969). (19) M. F. Rettig and R. S. Drago, J. Amer. Chem. SOC., 91, 3432 (1969). (20) For the calculation of AH, we used the usual equation (see eq 7 of ref (1964). was isolated (ref 2). 18). Since MnCp2 is "high spin" in solution (ref 2), we used g = 2.0, T = 310°K, S = 12.(21) (a) The ' A,, ground state for gaseous MnCp2 was proposed (ref 30) on the basis of photoelectron spectroscopy results. Orchard and coworkers (ref 4) have however disputed the necessity of invoking the ZA,g state to account for the PE spectrum.(33) Anderson and Rai (ref 22) estimate that the Kramers doublet derived from *A,, in FeCp2+ lies only ca. 260 cm-' above the lower Kramers doublet from ' E2, . (34) J. A.Abstract: Palladium atoms oxidatively insert aryl, alkyl, and acyl carbon-halogen bonds at low temperature to yield a new series of reactive intermediates ArPdX, RPdX, and RCOPdX. Efficiency of the insertion is in the order C-I > C-Br > C-CI. These species are formed in the absence of normal stabilizing ligands and their stabilities vary greatly depending on the organic group attached. For example ChFjPdBr is stable at room temperature in the air whereas CH3Pdl decomposes at exdihalide complexes were colored (yellow for chloride and bromides, orange for iodides) while the organopalladium complexes were white.

Suzuki–Miyaura Cross‐Coupling With Quasi‐Heterogeneous Palladium

“…However, the non-ligand-stabilized Pd(II) complex [PhPdBr] prepared by the cocondensation of palladium atoms with bromobenzene was reported to be unstable above À 116 8C. [17] It is also important to note that ligandless zero-valent palladium is not known to exist in solution as a molecular species. [18] It is unclear at this time, in what form or structure the soluble palladium exists.…”

Defluorinative Functionalization of Pd(II) Fluoroalkyl Complexes

“…The −CF 2 Ar fluorine resonance is downfield of the corresponding resonance in 1a (−69.08 ppm) and consistent with a cis rather than trans orientation of the −CF 2 Ar with respect to the phosphine ligand . Similar species (PEt 3 ) 2 Pd­(II)­CF 3 Br and (PEt 3 ) 2 Pd­(II)­(C 6 F 5 )Br are known to be stable at 25 °C …”

Late Transition Metals, Metal Halides, Metal Oxides, and Metal Sulfides (Group VIII)

“…Acyl chlorides oxidatively add to palladium atoms and nickel atoms. 56,57 In all examples studied the resultant RCOMC1 species very readily liberated CO. By carrying out low-temperature trapping experio ο…”

“…In benzene or toluene, however, C 6 F 5 PdBr is slowly de composed. 56 However, addition of almost any stabilizing ligand causes the breakup of the telomer and quantitative formation of C 6 F 5 PdBr(L) 2 . If bidendate ligands are employed cis-complexes are obtained, whereas monodentate ligands always yield trans complexes.…”

“…3 sum marizes the compounds prepared [56][57][58]. ' [65][66][67][68] With C 6 H 5 Br and Pd, a ther mally unstable C 6 H 5 PdBr species was formed.…”