Stepwise Successive Insertion of Carbon Monoxide and Allenes into Palladium−Carbon Bonds of Complexes Containing the Rigid Bidentate Nitrogen Ligand Bis(p-anisylimino)acenaphthene

Propadiene, 3-methyl-1,2-butadiene (DMA), and 2,4-dimethyl-2,3-pentadiene (TMA) reacted via migratory insertion with both neutral and ionic Pd(R)X( p -An-BIAN) (R = Me ( 1 ), C(O)Me ( 2 ); X = Cl ( a ), SO 3 CF 3 ( b )) complexes, containing the rigid nitrogen ligand bis( p -anisylimino)acenaphthene ( p -An-BIAN), resulting in the novel and stable allylpalladium complexes Pd(η 3 -C 3 H 4 R)X( p -An-BIAN) (R = Me ( 3 ), C(O)Me ( 6 )), Pd(η 3 -C 5 H 8 R)X( p -An-BIAN) (R = Me ( 4 ), C(O)Me ( 7 )), and Pd(η 3 -C 7 H 12 R)X( p -An-BIAN) (R = Me ( 5 ), C(O)Me ( 8 )), respectively (X = Cl ( a ), SO 3 CF 3 ( b )). The neutral complexes 6a and 7a reacted with carbon monoxide to form the acylpalladium complexes Pd(C(O)C 3 H 4 C(O)Me)Cl( p -An-BIAN) ( 9 ) and Pd(C(O)C 5 H 8 C(O)Me)Cl( p -An-BIAN) ( 10 ), respectively, while the analogous trifluoromethanesulfonate complexes 6b and 7b were completely inert toward CO. Complexes 9 and 10 reacted again with propadiene and DMA, respectively, to yield the allylpalladium complexes Pd(η 3 -C 3 H 4 C(O)C 3 H 4 C(O)Me)Cl( p -An-BIAN) ( 11 ) and Pd(η 3 -C 5 H 8 C(O)C 5 H 8 C(O)Me)Cl( p -An-BIAN) ( 12 ), respectively. Also insertion of norbornadiene in complex 10 was possible, yielding the ionic complex [Pd(C 7 H 8 C(O)C 5 H 8 C(O)Me)( p -An-BIAN)]Cl ( 13a ), which reacted with AgSO 3 CF 3 to give [Pd(C 7 H 8 C(O)C 5 H 8 C(O)Me)( p -An-BIAN)]SO 3 CF 3 ( 13b ). The novel complexes 9 − 12 are the first isolated and fully characterized complexes formed by successive insertion reactions of carbon monoxide and allenes, while 13a is the first isolated complex containing a metal-bonded ter-oligomer of carbon monoxide, an allene, and norbornadiene. The X-ray crystal structure of 7a has been determined and shows a distorted square pyramidal geometry in which the BIAN ligand is bonded to the palladium center in an unusual asymmetric fashion (Pd−N(1) = 2.144(7) Å; Pd−N(2) = 2.600(8) Å).