Homoleptic palladium complexes with phosphine-amide or iminophosphine ligands

Abstract

The reaction between Pd(dba) 2 and phosphino-amide ligands yielded the unexpected Pd(II) homoleptic complexes [Pd( o-Ph 2PC 6H 4CO-NR) 2] [R = iPr ( 1), Ph ( 2), 4-MeC 6H 4 ( 3), 4-FC 6H 4 ( 4)], in which an κ 2-P,N coordination mode for diphenylphosphine–benzamidate ligands is observed. In order to induce amide protonation in the ligands and subsequent κ 2-P,O coordination, compounds ( 1-4) were treated with HClO 4(aq) to give cationic complexes [Pd( o-Ph 2PC 6H 4CO-NHR) 2][ClO 4] 2 ( 5- 8). These complexes and the analogous with iminophosphine ligands [Pd( o-Ph 2PC 6H 4CH N-R) 2] [ClO 4] 2 [R = iPr ( 9), Ph ( 10)] can be alternatively obtained when [PdCl 2(PhCN) 2] is treated with AgClO 4 in the presence of the corresponding ligand. The reaction of Pd(dba) 2 with iminophosphines has also been explored, yielding in this case the Pd(0) derivatives [Pd( o-Ph 2PC 6H 4CH N-R) 2] [R = iPr ( 11), Ph ( 12)]. X-ray structures of ( 3), ( 4), ( 5), ( 8) and ( 9) have been established, allowing an interesting comparative structural discussion.