Palladium(II), platinum(II), ruthenium(II) and mercury(II) complexes of potentially tridentate Schiff base ligands of (E, N, O) type (E = S, Se, Te): Synthesis, crystal structures and applications in Heck and Suzuki coupling reactions

Schiff bases of 2-hydroxybenzophenone (HBP) (C6H5)(2-HOC6H4)C=N(CH2)(n)EAr (L1/L2: E = S, Ar = Ph, n = 2/3; L3/L4: E = Se, Ar = Ph, n = 2/3; L5/L6: E = Te, Ar = 4-MeOC6H4, n = 2/3) and their complexes [PdCl(L-H)] (L = L1-L6; 1, 2, 3, 5, 7, 11), [PtCl(L3-H/L5-H)] (4/8), [PtCl2(L4/L6)(2)] (6/12), [(p-cymene)RuCl(L5/L6)]Cl (9/13) and [HgBr2(L5/L6)(2)] (10/14) have been synthesized and characterized by proton, carbon-13, selenium-77 and tellurium-125 NMR, IR and mass spectra. Single crystal structures of L1, 1, 3, 4, 5 and 7 were solved. The Pd-E bond distances (angstrom): 2.2563(6) (E = S), 2.3575(6)-2.392(2) (E = Se); 2.5117(5)-2.5198(5) (E = Te) are near the lower end of the bond length range known for them. The Pt-Se bond length, 2.3470(8) angstrom, is also closer to the short values reported so far. The Heck and Suzuki reaction were carried out using complexes 1, 3, 5 and 7 as catalysts under aerobic condition. The percentage yields for trans product in Heck reaction were found upto 85%. (C) 2009 Elsevier B. V. All rights reserved.