Cyclopalladation of ( E)-N-(2,6-dichlorobenzylidene)(naphthalen-1-yl)methanamine: Synthesis and X-ray molecular structure of [κ 2- N, C1-η 2- C3, C4-Pd{(PhC [dbnd]CPh) 2–C 10H 6–CH 2–N [dbnd]CH–(2,6-Cl 2C 6H 3)}Cl]·CH 2Cl 2

Abstract

The reaction of equimolecular amounts of ( E)-N-(2,6-dichlorobenzylidene)(naphthalen-1-yl)methanamine ( 1) and Pd(OAc) 2 in acetic acid at 60 °C for 24 h produced a selective palladation at the 2 position of the naphthyl group of 1, which afforded the new acetato-bridged five-membered cyclopalladated dimer (μ-OAc) 2[(κ 2- C , N -Pd{(C 10H 6)–CH 2–N CH–(2,6-Cl 2C 6H 3)}] 2 ( 2), in which the imines adopted the Z configuration. A metathesis reaction between 2 and LiCl exchanged the acetato ligands of 2 for chloro ligands. This produced the dinuclear cyclopalladated compound (μ-Cl) 2[κ 2- C , N -Pd{(C 10H 6)–CH 2–N CH–(2,6-Cl 2C 6H 3)}] 2 ( 3), which consisted of a mixture of stereoisomers with imines in the E and Z configuration. Bridge-splitting reactions of the dimers 2 and 3 with py-d 5 and PPh 3 yielded the mononuclear compounds trans- N , L -[κ 2- C , N -Pd{(C 10H 6)–CH 2–N CH–(2,6-Cl 2C 6H 3)}(X)(L)]; 4 (X = OAc, L = py-d 5), 5 (X = OAc, L = PPh 3), 6 (X = Cl, L = py-d 5), 7 (X = Cl, L = PPh 3), in which the imine ligands adopted the Z configuration. In addition, 3 reacted with diphenylacetylene, which afforded the mononuclear organopalladium compound [κ 2- N , C1 -η 2- C3 , C4 -Pd{(PhC CPh) 2–C 10H 6–CH 2–N CH–(2,6-Cl 2C 6H 3)}Cl] ( 8). This compound derived from the insertion of two alkyne molecules into the C–Pd σ bonds of 3 and presented the imine ligand in a Z configuration. The crystal structure of 8·CH 2Cl 2 has been determined.