PALLADIUM(II) COMPLEXES OF 2-ACETYLPYRIDINE AND 2-FORMYLPYRIDINE 3-HEXAMETHYLENEIMINYL-THIOSEMICARBAZONES - A SYNTHETIC, SPECTRAL AND STRUCTURAL STUDY

Reaction of Li2PdCl4 with 2-acetyl- and. 2-formylpyridine 3-hexamethyl eneiminyl-thiosemicarbazones, HFohexim and HAchexim, respectively, aff ords the complexes [Pd(Achexim)Cl] and [Pd(Fohexim)Cl]. [Pd(Fohexim)Cl ] crystallizes in the triclinic space group P (1) over bar with a = 7. 9447(17)Angstrom, b = 9.6402(13) Angstrom, c = 10.3739(18) Angstrom; a lpha = 79.128(12)degrees, beta = 75.104(15)degrees and gamma = 75.558( 14)degrees. Crystals of [Pd(A chexim)Cl] are monoclinic, space group P 2(1)/n, with four formula units in a unit cell of dimensions a = 7.224 3(7) Angstrom, b = 9.6402(13) Angstrom, c = 24.937(3) Angstrom, and be ta = 104.048(9)degrees. Anions of HFohexim and HAchexim coordinate in a planar conformation to a central palladium(II) via the pyridyl nitro gen, azomethine nitrogen and thiolato sulfur atoms. The complexes have been characterized by spectroscopic techniques (IR and H-1 NMR). The protonation constants of HFohexim, K-a1 = 11.83 +/- 0.01 and K-a2 = 3. 70 +/- 0.02, were determined spectrophotometrically. (C) 1998 Elsevier Science Ltd. All rights reserved.