Complexes of Pd(II), η6-C6H6Ru(II), and η5-Cp*Rh(III) with Chalcogenated Schiff Bases of Anthracene-9-carbaldehyde and Base-Free Catalytic Transfer Hydrogenation of Aldehydes/Ketones and N-Alkylation of Amines

The condensation of 2-(phenylsulfanyl)ethylamine and 2-(phenylselenyl)ethylamine with anthracene-9-carbaldehyde resulted in Schiff bases [PhS(CH2)(2)C=N-9-C14H9](L1) and [PhSe(CH2)(2)C=N-9-C14H9] (L2), respectively. Na-2[PdCl4] treatment of L1/L2 in acetone-water mixture for 3 h at room temperature gave palladacycle [PdCl(C-, N, S/Se)] (1/2; L1/L2-H = (C-, N, S)/(C-, N, Se)). The reaction of [eta(6)-C6H6)RuCl(mu-Cl)](2) with L1/L2 in methanol for 8 h at room temperature (followed by addition of NH4PF6) afforded half-sandwich complex [(eta(6)-C6H6)Ru(L)Cl] [PF6], 3/4: (L = L1/L2 (N, E) ligand). The reaction of [(eta(5)-Cp*)RhCl(eta-Cl)](2) with L1/L2 in the presence of CH3COONa at 50 degrees C (followed by treatment with NH4PF6) resulted in [(eta(5)-Cp*)Rh(L-H)][PF6], 5/6: (L = L1/L2). On carrying out the reaction of [(eta(5)-Cp*)RhCl(eta-Cl)](2) with these ligands at room temperature and in the absence of CH3COONa, complex [(eta(5)-Cp*)Rh(L)Cl][PF6], 7/8 (L = L1/L2 E (N, E) ligand), was formed. Complexes 1-8 were authenticated with. H-1, C-13{H-1}, and Se-77{H-1} NMR spectroscopy, high-resolution mass spectrometry, elemental analyses, and single-crystal X-ray diffraction. The moisture- and air-insensitive complexes of Pd(II) (1, 2), Ru(II) (3, 4) and Rh(III) (5-8) were thermally stable. Palladium and rhodium (under base-free condition) species efficiently catalyzed transfer hydrogenation (propan-2-ol as H-source). At room temperature conversion was 90% in TH catalyzed with 0.2 mol % of 2. N-Alkylation of aniline with benzyl alcohol under base-free condition was promoted by 3-8. The 7 was most efficient for the two base-free catalytic reactions. For TH optimum loading of 1-2 and 5-8 as catalyst is 0.05-0.2 and 0.2-0.5 mol % respectively. The optimum temperatures are 80 and 100 degrees C for TH and N-alkylation, respectively. The optimum loading of 3-8 for N-alkylation is 0.5 mol %. Mercury poisoning test supported homogeneous pathway for the two catalytic reactions. The rhodacycles probably gave real catalytic species by losing a Cp* group.