Preparation of phenyl(acetylacetonato)nickel(II) complexes with tertiary phosphine ligands and their reactions with organic halogen compounds and olefins

Abstract

Treatment of Ni(acac) 2 (acac = acetylacetonato ligand) with AlPh 3 Et 2O in the presence of PR 3 gave PhNi(acac) (PR 3) n (n = 1; R = Ph( 1 ), cyclo-C 6H 11 ( 2 ), Et( 3 ); n = 2; R = Et( 4 )). The pyrolysis of 1 in toluene gave one equivalent of biphenyl indicating that oxidative addition of PPh 3 to Ni involving the PC bond cleavage took place. Reactions of 1 – 3 with organic halogen compounds (R′-X) afforded cross coupling products, Ph-R′. Complexes 1 – 3 reacted with olefinic compounds such as CH 2CH 2, CH 3CHCH 2, CH 3COOCHCH 2, CH 3OCOCHCH 2, C 6H 5CHCH 2, and CH 2CHCH 2X (X = OCOCH 3, OCOH, Br, OH, OC 6H 5, and OCH 2CHCH 2) to give phenyl-substituted organic compounds. Examination of the reaction products suggests that these substitution reactions may proceed mainly through (i) olefin coordination to Ni, (ii) insertion of olefin into PhNi bond, and (iii) β-elimination reactions to yield olefinic products. In the arylation of vinyl acetate and allylic compounds, phenyl-substituted hydrocarbon products were obtained in fairly high yields suggesting that the CO or CX bond cleavage reaction is taking place.