Monatshefte fu ¨r Chemie 138, 175–189 (2007) DOI 10.1007/s00706-007-0585-6 Printed in The Netherlands Invited Review Structural Features of ONS-Donor Salicylidene Schiff Base Complexes Ahmed A. Soliman 1; and Wolfgang Linert 2 1 Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt 2 Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria Received November 8, 2006; accepted (revised) December 19, 2006; published online February 22, 2007 # Springer-Verlag 2007 Summary. This review article summarizes the structural fea- tures of complexes of salicylidene Schiff bases containing, in addition to the phenolic-OH and the azomethine (–RC¼N–) groups, a thiole group, and=or a sulfur atom participating in coordination. Structural aspects of metal complexes of sali- cylidene-2-aminothiophenol, salicylidene-3-aminothiophenol, salicylidenethiosemicarbazone, salicylidenedithiocarbazates, salicylidenedithiocarbazates, salicylideneaminopropyleneami- nocyclopentenedithiocarboxylates, salicylideneimidazoles, and salicylidene-thiosalicylidene-1,3-propanediamine are reported. Keywords. Salicylidene Schiff bases; ONS-Donors; Metal complexes. Introduction Schiff bases have played an important role in the development of coordination chemistry as they read- ily form stable complexes with most of the transition metals. They show interesting properties, e.g., their ability to reversibly bind oxygen [1], catalytic activ- ity in hydrogenation of olefins [2] and transfer of an amino group [3], photochromic properties [4], and complexing ability towards toxic metals [5]. The interest of studying Schiff bases containing ONS- donors arose from their significant antifungal, anti- bacterial, and anticancer activities [6]. In addition, the presence of both a hard and a soft donor group in one ligand increases the coordination ability towards hard as well as soft acidic metals. Metal complexes of Schiff bases derived from sal- icylaldehyde and various amines have been widely investigated [7–13]. The salicyaldehyde-thio-Schiff bases have recently acquired a considerable impor- tance due to their chemical and especially their promising biological properties [14, 15]. Antibacte- rial [16], antineoplastic [17], antimalarial [18], and antiviral [19] behaviour has been found. Relation- ships are evident between chelate formation in the complexes and the in vivo activity [20–23]. In the area of bioinorganic chemistry interest in Schiff base complexes has centred on the role such complexes may have in providing synthetic models for the metal containing sites in metalloproteins and metalloen- zymes [24]. This review article focuses on the complexes of ONS-donor salicylidene Schiff bases, i.e. those containing, in addition to the phenolic OH and the azomethine (–RC¼N–) groups, a thiole group, and=or a sulfur atom participating in coordination. The structural features of salicylidene-2-aminothio- phenol, salicylidene-3-aminothiophenol, salicylide- nethiosemicarbazone, salicylidene-dithiocarbazates, salicylidenedithiocarbazates, salicylideneami- nopropyleneaminocyclopentenedithiocarboxylates, salicylideneimidazoles, and salicylidene-thiosalicy- lidene-1,3-propanediamine are reported.  Corresponding author. E-mail: ahmedsoliman61@gmail. com