Zum Substituenteneinfluß in neuen Ni(0)-Butadiin-Komplexen

It has been shown tha t d isubstituted butadiynes react with (Ph3P)2N i(C2H 4) [1] or (cod)2Ni [2] in the presence of Ph3P to yield m ononuclear complexes (Ph3P)2N i(//2( l :2 ) -R 'C = C C = C R ) (R ' = R = SiM e3 (1), 'B u (2) Ph (3) and R ' = 'Bu, R = SiMe3 (4) ör R ' = Ph, R = SiM e3 (5)) or dinuclear com plexes {(Ph3P)2Ni}2(//-? /2(l :2),^2(3 :4 ) -R 'C = C -C = C R ) (R ' = R = SiM e3 (6), Ph (7)) depending on the stoichiom etry applied. For R ' = R = 'B u or R ' = 'Bu, R = SiM e3 the dinuclear com plexes could not be obtained. Some of the m ononuclear com ple­ xes with symmetrical (R ' = R = SiM e3, 'Bu, Ph) and unsymmetrical disubstituted (R ' = 'Bu, R = SiM e3) butadiynes have been characterized by X-ray crystal structure analysis to study the influence of different substituents on the structural details of the bonding. As com pared to the alkyne complexes (Ph3P)2Ni(?72-R C = C R ) the influence of the different substituents in m ononuclear butadiyne-com plexes (Ph3P)2Ni(?/2( l :2 ) -R 'C = C -C = C R ) is strongly dim in­ ished by the conjugated uncom plexed C = C triple bond.