Synthesis, Characterization and Catalytic Activity of New Bis(N-2,6-diphenylphenol-R-salicylaldiminato)Pd(II) Complexes in Suzuki-Miyaura and CO2 Fixation Reactions

Abstract A series of bulky N -2,6-diphenylphenol-R-salicylaldimines ( HL x ) and their corresponding bis( N -2,6-diphenylphenol-R-salicylaldiminato)Pd(II) complexes ( X) , where R = H ( 1 ), 3-OCH 3 ( 2 ), 4-OCH 3 ( 3 ), 5-OCH 3 ( 4 ), 3-Me ( 5 ), 5-Me ( 6 ), 5-C(CH 3 ) 3 ( 7 ), 3-C(CH 3 ) 3 ( 8 ) and 3,5-di-C(CH 3 ) 3 ( 9 ) have been synthesized. Their structures characterized by elemental analyses, IR, UV/vis, 1 H NMR and 13 C NMR spectroscopic techniques. X-ray crystallography shows that complex 3 crystallizes in the triclinic P-1space group with one trans -[PdL 3 2 ] molecule and two acetic acid (C 2 H 4 O 2 ) molecules in the unit cell. All X compounds are proved to be as efficient homogeneous catalysts for both Suzuki-Miyaura cross-coupling reactions of various aryl bromides and cyclic carbonates synthesis from CO 2 and epoxides are reported under appropriate conditions (2 h, 100 °C and 1.6 MPa pressure) without use of phosphine ligands.