TY - JOUR
T1 - Theoretical studies of the oxidative addition of PhBr to Pd(PX3)2 and Pd(X2PCH2CH2PX2) (X = Me, H, Cl)
AU - Fazaeli, Reza
AU - Ariafard, Alireza
AU - Jamshidi, Saiedeh
AU - Tabatabaie, Elham S.
AU - Pishro, Khatereh A.
PY - 2007/8/15
Y1 - 2007/8/15
N2 - The density functional theory calculations were used to study the influence of the substituent at P on the oxidative addition of PhBr to Pd(PX3)2 and Pd(X2PCH2CH2PX2) where X = Me, H, Cl. It was shown that the Cipso-Br activation energy by Pd(PX3)2 correlates well with the rigidity of the X3P-Pd-PX3 angle and increases via the trend X = Cl < H < Me. The more rigid the X3P-Pd-PX3 angle is, the higher the oxidative addition barrier is. The exothermicity of this reaction also increases via the same sequence X = Cl < H < Me. The trend in the exothermicity is a result of the Pd(II)-PX3 bond strength increasing faster than the Pd(0)-PX3 bond strength upon going from X = Cl to Me. Contrary to the trend in the barrier to the oxidative addition of PhBr to Pd(PX3)2, the Cipso-Br activation energy by Pd(X2PCH2CH2PX2) decreases in the following order X = Cl > H > Me. This trend correlates well with the filled dπ orbital energy of the metal center. For a given X, the oxidative addition reaction energy was found to be more exothermic for the case of X2PCH2CH2PX2 than for the case of PX3. This effect is especially more important for the strong electron donating phosphine ligands (X = Me) than for the weak electron donating phosphine ligands (X = Cl).
AB - The density functional theory calculations were used to study the influence of the substituent at P on the oxidative addition of PhBr to Pd(PX3)2 and Pd(X2PCH2CH2PX2) where X = Me, H, Cl. It was shown that the Cipso-Br activation energy by Pd(PX3)2 correlates well with the rigidity of the X3P-Pd-PX3 angle and increases via the trend X = Cl < H < Me. The more rigid the X3P-Pd-PX3 angle is, the higher the oxidative addition barrier is. The exothermicity of this reaction also increases via the same sequence X = Cl < H < Me. The trend in the exothermicity is a result of the Pd(II)-PX3 bond strength increasing faster than the Pd(0)-PX3 bond strength upon going from X = Cl to Me. Contrary to the trend in the barrier to the oxidative addition of PhBr to Pd(PX3)2, the Cipso-Br activation energy by Pd(X2PCH2CH2PX2) decreases in the following order X = Cl > H > Me. This trend correlates well with the filled dπ orbital energy of the metal center. For a given X, the oxidative addition reaction energy was found to be more exothermic for the case of X2PCH2CH2PX2 than for the case of PX3. This effect is especially more important for the strong electron donating phosphine ligands (X = Me) than for the weak electron donating phosphine ligands (X = Cl).
KW - Density functional theory calculations
KW - Oxidative addition
KW - Palladium
UR - http://www.scopus.com/inward/record.url?scp=34547093220&partnerID=8YFLogxK
U2 - 10.1016/j.jorganchem.2007.06.011
DO - 10.1016/j.jorganchem.2007.06.011
M3 - Article
AN - SCOPUS:34547093220
SN - 0022-328X
VL - 692
SP - 3984
EP - 3993
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
IS - 18
ER -