Doesn't matter much for a basic suzuki (i.e. if the aryl-halide is active such as chloro0pyridine or aryl bromide/iodide). The excess boronic acid will reduce the starting Pd(II) catalist to the active Pd(O). Alternatively you can used Pd(PPh3)4, or Pd2dba3/PPh3, or a second generation Pd(PPh3)-type precatalyst developped by Buchwald but honestly, for a standard coupling, Pd(PPh3)4 should work alright.

Doesn't matter much for a basic suzuki (i.e. if the aryl-halide is active such as chloro0pyridine or aryl bromide/iodide). The excess boronic acid will reduce the starting Pd(II) catalist to the active Pd(O). Alternatively you can used Pd(PPh3)4, or Pd2dba3/PPh3, or a second generation Pd(PPh3)-type precatalyst developped by Buchwald but honestly, for a standard coupling, Pd(PPh3)4 should work alright.

Agree with Pierre-Andre, Pd(PPh3)4 should work in most cases. Other reaction conditions are important as well, for example, the choice of the base, solvent, etc. It is difficult to give general recommendations if you don't know the substrate structure.

Dear Muhammad,

Let me put forwards some mechanistic facts about Pd(II) and Pd(0) catalyzed reactions . I hope this will help you to get the answer for your query.

Palladium(II) catalysis differs mechanistically from palladium(0) catalysis and in coupling reactions has often been overshadowed by the significant advances in palladium(0) catalysis. Whereas palladium(0)-catalyzed coupling reactions initially utilize organic oxidants, which are ultimately included in the product, palladium(II)-catalyzed coupling reactions use a

terminal oxidant, which is not incorporated into the final product. As palladium(II)-catalyzed coupling reactions often generate palladium(0) at the end of each turnover, a reoxidant to regenerate palladium(II) is usually required

In the palladium(II)-hydride pathway, a palladium–hydride intermediate undergoes direct reaction with O2 to generate a palladium(II)–hydroperoxide intermediate. Protonation of the palladium(II)–hydroperoxide intermediate reforms the palladium(II) catalyst and hydrogen peroxide is released.

As the name implies, the palladium(0)-protonolysis pathway involves the formation of palladium(0). he palladium(0) intermediate is proposed to be generated by reductive elimination of an acid (HX) from the palladium(II)–hydride intermediate.

The palladium(0) intermediate is oxidatively added to O2 to form a palladium(II)–peroxo intermediate, which then reacts with two equivalents of acid to first provide a palladium(II)–hydroperoxide intermediate and subsequently the initial palladium(II) catalyst and hydrogen

peroxide.

Mechanistic investigations have, so far, not been able to provide conclusive evidence for one mechanistic pathway over the other, and it seems likely that either pathway may be possible, depending on the ligands, solvents, additives and substrates used.

Pd(0) is more active than Pd(II) because it react with more ligand to become 18e

you can generate Pd(0) from react Pd(II) with triethylamine

Ayham, I have a question to you. Generation of Pd(0) from Pd(II) requires reduction; could you explain how exactly would triethylamine do this ?

Yes i will put the solve on paper

also you can generate it by react Pd(OAC)2 with PPh3 , if you want a mechanism " tell me Doc

For couplings of this type you need zero-valent palladium Pd(0) catalyst because oxidative addition between Pd(0) and haloaromate proceeds and intermediary complex with Pd(II) is formed:

Pd(0)(PPh3)4 + ArBr → Pd(II)Br(Ar)(PPh3)2 + 2 PPh3

Pd(PPh3)4 can be prepared in two steps from Pd(II) precursors (in methaol?):

PdCl2 + 2 PPh3 → cis-PdCl2(PPh3)2

cis-PdCl2(PPh3)2 + 2 PPh3 + 2.5 N2H4 → Pd(PPh3)4 + 0.5 N2 + 2 N2H5+Cl-

Both steps may be carried out in a one-pot reaction, without isolating and purifying the cis-PdCl2(PPh3)2 intermediate. (L. Malatesta and M. Angoletta, "Palladium(0) compounds. Part II. Compounds with triarylphosphines, triaryl phosphites, and triarylarsines" J. Chem. Soc., 1186 (1957). doi:10.1039/JR9570001186). Reductants other than hydrazine can be employed (NaBH4, H2).

The compound is sensitive to air, but can be purified by washing with methanol to give the desired yellow powder. It is usually stored cold under argon. (D. R. Coulson; Satek, L. C.; Grim, S. O. (1972). "Tetrakis(triphenylphosphine)palladium(0)". Inorg. Synth. Inorganic Syntheses 13: 121. doi:10.1002/9780470132449.ch23.)

It really doesn't matter, but sometimes it depends on your reaction mixture. For example, PdCl2(PPh3)2 should be reduced to Pd(0) with green formalism of 14 e- to be active and this is done with NEt3, while for Pd(PPh3)4, it is 18 e-, so two PPh3 ligands should be removed in order to be active catalyst, and this depends on the solvent you use, if you use THF for example, just room temperature is enough, while in toluene you have to heat for at least 80 degrees to get Pd(PPh3)2. Moreover, some sonogoshira coupling reactions can take place without the use of Cu(l) precatalyst when using Pd(0), while with Pd(II) you should use Cu, so if your reagent is sensitive to Cu, Pd(0) should be used