Some attempts to prepare chelating nitrophenylpalladium(II) complexes. Synthesis of covalent arylpalladium(II) perchlorate complexes. Crystal and molecular structure of catena- trans- {[Pd{C 6H 2(NO 2) 3-2,4,6} (tht) 2(H 2O)]{ClO 4} n (tht = tetrahydrothiophene)

Abstract

Complexes [Pd(R)CIL 2] [R = C 6H 2(NO 2) 3-2,4,6, L = tetrahydrothiophene (tht) or PPh 3, or L 2 1,5-cyclooctadiene (COD); R = C 2H 3Me-2,NO 2-6, L 2 = 1,10-phenanthroline (phen) or 2,2′-bipyridyl (bipy)l react with AgClO 4 to give the corresponding perchlorato-complexes [Pd(R)(OClO 3)L 2]. Of these only some could be isolated and characterized [R = C 6H 2(NO 2)3-2,4,6, L = tht ( 1); R = C 6H 3 Me-2-NO 2-6, L 2 = phen ( 2) or bipy ( 3)]. These complexes, and solutions of the other non-isolated perchlorato-complexes, react with different neutral ligands to give cationic complexes [Pd(R)L 2L′]ClO 4 [R = C 6H 2(NO 2) 3 -2,4,6, L = tht, L′ = H 2O ( 4); L′= PPh 3, L 2 = phen ( 5) or COD ( 6); R = C 6H 3Me-2-NO 2-6, L′= PPh 3, L 2 = phen ( 7)]. The complex (PhCH 2PPh 3)[Pd(R)Cl 2(dmso)] (R = C 6H 2(NO 2) 3-2,4,6, dmso = dimethyl sulphoxide) reacts with Ag 2(OX) (ox = oxalate) to give (PhCH 2PPh 3)[Pd(R)(ox)-(dmso)l ( 8) and (NMe 4) 2[Pd,(R) 2Cl 2 (μ-Cl) 2] (R = C 2H 3Me-2-NO 2-6) reacts with Tl(acac) (acacH = acetylacetone) to give [Pd(R)(acac)] ( 9). IR studies suggest that in this complex the aryl ligand is chelating. The crystal structure of trans-[Pd{C 6H 2(NO 2) 3-2,4,6}(tht) 2 (H 2O)] ClO 4 shows that each perchlorate anion bridges two cations using two different oxygen atoms which gives a catena structure with a helical frame. The anion-cation interaction seems to be through hydrogen bonding with the coordinated water molecule. CC bond angles in the trinitrophenyl group support suggestions that nitro groups exert a - I inductive effect rather than a - M effect on the ring electron density.