Synthese und Struktur von (R3P)Ni(1,6‐Heptadiin)‐Komplexen

Synthesis and Structure of (R3P)Ni(1,6‐Heptadiin) Complexes Displacement of the alkene ligand in Ligand‐Ni(0)(1,6‐diene) complexes by 1,6‐heptadiyne, the parent 1,6‐diyne, affords the complexes (Me3P)Ni(η2,η2‐C7H8) (1) and (Ph3P)Ni(η2,η2‐C7H8) (2). According to an X‐ray structure analysis of the PMe3 derivative 1 the nickel atom is ideally trigonal‐planar coordinated by the phosphane and both CC bonds. The increased stability of the complexes as compared to Ligand‐Ni(HCCH)2 complexes is referred to the strong chelating effect which is special to the 1,6‐functionalization. The compounds can be considered to be model complexes for the key intermediates of numerous transition metal‐mediated coupling reactions of (substituted and unsubstituted) 1,6‐diynes.