Synthesis and reactivity studies on alkyl-aryloxo complexes of nickel containing chelating diphosphines:: cyclometallation and carbonylation reactions

Nickel alkyl-aryloxo complexes of composition Ni(R)(O-C(6)Hl(3)-2,6-Me-2)(P-P) (R=CH2SiMe3, CH3, CH2CMe2Ph; P-P =PPr'(2)(CH2)(n)PPr'(2), n=2 (dippe) or 3 (dippp)) have been synthesized. While the (trimethylsilyl)methyl and the methyl derivatives are stable in solution at room temperature, the bis-neophyl (R = CH2CMe2Ph) complexes undergo a cyclometallation reaction that leads to the metallacvcles N<i(CH2CMe2-o-C-6)H-4)(P-P)over bar> together with 2,6-dimethylphenol. The alkyl-aryloxo complexes cleanly react with carbon monoxide giving products resulting from CO insertion and reductive elimination, i.e. Ni(CO)(2)(P-P) and the corresponding 2.6-dimethylphenyl carboxylates quantitatively. (C) 2002 Elsevier Science B.V. All rights reserved.