tmeda-NICKEL-KOMPLEXE. I. (tmeda)Ni(η2-C4H6)2 and 2-C4H6)>2(η2,η2-C4H6)

Article abstract of DOI:10.1016/S0022-328X(00)99366-5

Tris(ethene)nickel(0) reacts with tmeda and butadiene in ether below -40 deg C to yield a deep-red solution of (tmeda)Ni(η²-C4H6)2 (3a), from which red crystals of the thermolabile dinuclear complex <(tmeda)Ni(η²-C4H6)>2(η²,η²-C4H6) (3b) can be separated.Results in the formation of mononuclear 3a, which also forms upon dissociation of 3b in solution, was identified from its 1H and 13C NMR spectra.Above -40 deg C, 3a,b decompose in solution, with coupling of the butadiene ligands to afford Ni(η³,η³,η²-C12H18), which was shown to be an intermediate of the nickel-catalyzed cyclotrimerisation reaction of butadiene.Thus 3a, b are the first butadiene complexes of nickel that are catalytically active despite the presence of stabilizing ligands.