Details

Autor(en) / Beteiligte

• Castonguay, Annie
• Beauchamp, André L
• Zargarian, Davit

Titel

Preparation and Reactivities of PCP-Type Pincer Complexes of Nickel. Impact of Different Ligand Skeletons and Phosphine Substituents

Ist Teil von

• Organometallics, 2008-11, Vol.27 (21), p.5723-5732

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2008

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Reaction of the diphosphine ligand i-Pr2P(CH2)5P(i-Pr)2 with NiBr2 at 110 °C gives a mixture of the 16-membered bimetallacycle {i-Pr2P(CH2)5P(i-Pr)2}2Ni2Br4, 1, and the pincer-type complex {(i-Pr2PCH2CH2)2CH}NiBr, 2; the latter can also be obtained by heating 1 in the presence of 4-(dimethylamino)pyridine or under vacuum. Complex 2 undergoes transmetalation with RMgCl or RLi to give {(i-Pr2PCH2CH2)2CH}NiR (R = Me (4), CCMe (5), Ph (6), n-Bu (7), and CCPh (8)); the phenylacetylide derivative 8 was also obtained from the reaction of PhCCH with 4, 5, or 7. The Ni−Me derivative 4 reacts with PhX (X = I, Br, Cl) to give the product of C−C coupling reaction (Ph−Me) and the Ni−X analogues of 2, and tests have shown that 2 is a competent catalytic precursor for the coupling of PhCl and MeMgCl. The available evidence suggests that this catalytic process does not involve Ni0 intermediates. Indeed, cyclic voltammetry measurements show that 2 can undergo two consecutive oxidations, and attempts to generate isolable high-valent species yielded the five-coordinate, 17-electron NiIII species {(i-Pr2PCH2CH2)2CH}NiX2, 9, from the reaction of 2 with FeX3 (X = Cl, Br). Characterization of all new complexes, including X-ray diffraction studies on single crystals of complexes 1−6 and 9, is described.