Aktivierung von Kohlendioxid an Uebergangsmetallzentren: Selektive Cooligomerisation mit Hexin(-3) durch das Katalysatorsystem Acetonitril/Trialkylphosphan/Nickel(0) und Struktur eines Nickel(0)-Komplexes mit side-on gebundenem Acetonitril

Article abstract of DOI:10.1016/0022-328X(87)80100-6

CO2 reacts with hexyne(-3) in a catalytic reaction under formation of tetraethyl-2-pyrone, when the catalytic system alkyl₃P/acetonitrile/nickel(0) is used.The selectivity of this homogeneous-catalytic reaction can be increased to values of 96percent when phosphanes of high basicity and small cone angle are used.The investigation of the system Ni(COD)2/tricyclohexylphosphane/acetonitrile shows that acetonitrile can act as ligand in complexes of nickel(0).A yellow-brown tetranuclear complex was isolated, the structure of which was determined by X-ray diffraction studies.Acetonitrile acts as bridging ligand and is coordinated alkyne-analogously to one nickel center with its triple bond.The free electron pair of the nitrogen atom is bonded to a second nickel atom.Some reaction steps of this selective catalytic reaction are discussed.This reaction represents the first example of a selective homogeneous-catalytic co-oligomerization between CO2 and an unsaturated substrate which takes place under C-C linkage with a 3d-transition metal.