Synthesis, structural, spectroscopic and reactivity properties of a new N-2,3,4-trifluorophenyl-3,5-di-tert-butylsalicylaldimine ligand and its Cu(II) and Pd(II) complexes Veli T. Kasumov a, *, Ibrahim Uc ¸ar b , Ahmed Bulut b a Department of Chemistry, Harran University, Osmanbey, 63300 Sanlıurfa, Turkey b Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Kurupelit, Samsun, Turkey 1. Introduction The design, synthesis and structural characterization of salicylaldimine complexes are a subject of current interest due to their interesting structural, magnetic, spectral, and catalytic and redox properties, use as models for enzymes and various theoretical interests [1–3]. Our interest in these type of complexes was associated with coordination chemistry, electron transfer reactivity and antiox- idant effectiveness of N-salicylaldimines and other ligands transition metal(II) complexes bearing bulky 2,6-di-tert-butylated phenol fragments [4–6]. The unique properties of ligands with these types of bulky phenols are their capability to form stable metal(II)–phenoxyl or semiquinone type radical complexes upon chemical or electrochemical oxidation [3], which are extensively used for elucidating the chemistry and functionality of enzymatic and non-enzymatic processes [7]. In addition, along with unexpected oxidative C–C coupling reactions in the complexation of N-1-HO-2,6-di-tert-butylphenyl-X-salicylaldimines and other ligands with Cu(II), the reduction of some Cu(II) and Pd(II) complexes in the interaction with tri-arylphosphines [(XC 6 H 5 ) 3 P] were also observed [4–6]. Our recent studies on coordination chemistry of N-X-pheny- l(alkyl)-3,5-di-tert-butylsalicylaldimines, prepared from 3,5-di- tert-salicylaldehyde and mono- (F, Cl, Br, CH 3 , OCH 3 ) and di- substituted (F, Cl, CH 3 , OCH 3 ) aniline derivatives or various n- alkyl(cyclic) amines, demonstrated that they not only easily form bis-ligand chelates only with Cu(II), Co(II) and Pd(II), but they also exhibit less complexing ability with respect to Ni(II), VO(II), Mn(II), Zn(II) and Cd(II) metal ions [8–11]. Our repeated attempts to prepare complexes of these metals with above salicylaldimnes were unsuccessful. It is interesting to note that in the studies of the catalytic activity of early transition metals complexes (named FI Catalysts) with ligands similar to above, Fujita and co-workers demonstrated that bulky substituents ortho to the phenoxy-oxygen in these complexes to play a key role in achieving both living and isospecific polymerization and increase their catalytic activity [12]. Further investigations aimed at developing higher performance FI Cata- lysts for living ethylene/propylene polymerization led to the discovery of an exceptional fluorinated Ti-FI Catalyst [13]. In order to investigate the mechanism of this unusual polymerization process, complexes which varied in the number and positions of fluorine atoms in imine nitrogen-phenyl group were synthesized [14,15]. The results of the investigations indicate that living Journal of Fluorine Chemistry 131 (2010) 59–65 ARTICLE INFO Article history: Received 17 July 2009 Received in revised form 7 October 2009 Accepted 7 October 2009 Keywords: Trifluorinated-3,5-di-tert- butylsalicylaldimine Cu(II) and Pd(II) complexes X-ray structure Spectroscopy Chemical oxidation ABSTRACT A new N-2,3,4-trifluorophenyl-3,5-di-tert-butylsalicylaldimine (1) complexes with Cu(II) (2) and Pd(II) (3) have been synthesized and characterized by X-ray crystallography, UV–Vis, IR, 1 H NMR and EPR spectroscopic techniques. The X-ray crystal structure of complex 2 reveals tetrahedrally distorted square-planar coordination geometry around Cu(II). The UV/Vis and EPR results indicate that the solid state geometry of 2 remains unchanged in solutions. Chemical oxidation of 3 with Ce(IV) in CHCl 3 generates relatively stable Pd(II)–phenoxyl radical complex (g = 2.0073). The results related with the chemical oxidation of 2 and 3 as well as the catalytic activity of 3 in the hydrogenation of PhNO 2 are presented. ß 2009 Elsevier B.V. All rights reserved. * Corresponding author. Fax: +90 414 3440051. E-mail address: vkasumov@harran.edu.tr (V.T. Kasumov). Contents lists available at ScienceDirect Journal of Fluorine Chemistry journal homepage: www.elsevier.com/locate/fluor 0022-1139/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jfluchem.2009.10.005