Synthesis and Characterization of Proximal Dinuclear Complexes of Palladium Supported by 2,6-Bis(arylimino)phenoxy (aryl = 2,6-diisopropylphenyl and 2,4,6-tri-tert-butylphenyl) and 3,6-Bis(imino(2,6-diisopropylphenyl))pyridazine Ligands

Abstract

Two kinds of binucleating ligands, 2,6-bis(arylimino)phenoxy (1a: aryl = 2,6-diisopropylphenyl; 1b: aryl = 2,4,6-tri-tert-butylphenyl) and 3,6-bis(imino(2,6-diisopropylphenyl))pyridazine (2), were prepared, and their proximal complexation with two palladium atoms was studied. Treatment of the sodium compounds of 1a,b with 2 equiv of PdCl2(PhCN)2 and PdMeCl(cod) afforded the corresponding homobimetallic complexes, [2,6-bis(arylimino)phenoxy][RPd(μ-Cl)PdR] (4a: R = Cl, aryl = 2,6-diisopropylphenyl; 4b: R = Cl, aryl = 2,4,6-tri-tert-butylphenyl; 7a: R = Me, aryl = 2,6-diisopropylphenyl; 7b: R = Me, aryl = 2,4,6-tri-tert-butylphenyl), whose structures were characterized spectroscopically and crystallographically. In the reaction between the sodium compound of 1a with 1 equiv of PdCl2(PhCN)2, we detected the NaCl adduct of mononuclear palladium species 5a, which, upon release of NaCl, formed a dimeric complex, ([2,6-bis(2,6-diisopropylphenylimino)phenoxy](PdCl])2 (4a), as confirmed by X-ray analysis. Complexation of 2 with 2 equiv of PdCl2(PhCN)2 and PdMeCl(cod) in the presence of 1 equiv of AgBF4 resulted in the formation of the corresponding cationic complexes ([3,6-bis(imino(2,6-diisopropylphenyl))pyridazine][RPd(μ-Cl)PdR])(BF4) (9a: R = Cl; 9b: R = Me), whose RPd(μ-Cl)PdR skeletons (R = Cl and Me) were revealed spectroscopically and crystallographically.