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Free keywords:
ALKENE LIGANDS; 1,6-DIENES; NICKEL COMPLEXES
Abstract:
Ni(CDT) dissolves in 1,6-heptadiene with displacement of the CDT to yield the dinuclear homoleptic product rac/meso-(μ- η2,η2-C7H12){Ni(η2, η2-C7H12)}2 (1) as a mixture of stereoisomers, in which the nickel atoms are trigonal-planar coordinated by a chelating 1,6-diene ligand and one C=C bond of a bridging diene ligand. The stereoisomers differ in the coordination mode of the bridging diene ligand.-The bridging diene ligand in 1 can be displaced by various donor/acceptor molecules. In pentane, 1 reacts with ethene to yield a solution of mononuclear (C2H4)Ni(η2,η2-C7H12) (2). With alkynes unstable complexes are formed of which the anticipated ethyne derivative (C2H2)Ni(η2,η2-C7H12) (3) decomposes explosively at – 100°C. With isocyanides, methylenephosphoranes, methyllithium, amines, pyridines, phosphanes, and phosphites (i.e. C, N, P donors) crystalline complexes of type L-Ni(η2.η2 C7H12) have been obtained, of which the derivatives with L=tBuN=C 4, Me3PCH2 5, LiCH3 6, C7H13N 7, C5H5N 8, Me3P 9, iPr3P 10, Ph3P 11, (PhO)3P 12 are characterized here. For 11 the crystal structure has been determined.
