Author's personal copy A tetranuclear copper(II) complex with bis(o-aminobenzaldehyde)thiocarbohydrazone Diana Dragancea a, * , Anthony W. Addison b, * , Matthias Zeller c , Michael E. Foster b , Michael J. Prushan d , Laurence K. Thompson e , Mihail D. Revenco a , Allen D. Hunter c a Laboratory of Coordination Chemistry, Institute of Chemistry, Academy of Sciences of Moldova, Academiei str. 3, MD-2028, Chisinau, Moldova b Chemistry Department, Drexel University, Philadelphia, PA 19104-2816, USA c STaRBURSTT – Cyberdiffraction Consortium and Chemistry Department, Youngstown State University, Youngstown, OH 44555-3663, USA d Chemistry Department, LaSalle University, Philadelphia, PA 19141-1108, USA e Chemistry Department, Memorial University, St. John’s, NF, Canada A1B 3X7 article info Article history: Received 1 October 2009 Received in revised form 29 January 2010 Accepted 4 February 2010 Available online 12 February 2010 Keywords: Copper(II) complexes Thiocarbohydrazone Schiff base X-ray structure Antiferromagnetism abstract Bis(o-aminobenzaldehyde)thiocarbohydrazone (HL) forms with copper(II) nitrate a tetranuclear complex [Cu 2 (L)(NO 3 ) 3 ] 2 2H 2 O, in which two dinuclear units are joined by nitrate bridges. The dihydrazone ligand behaves ditopically, providing NNS and NNN binding sites, with the four coppers essentially in a square- pyramidal geometry. The tetranuclear molecule displays intramolecular magnetic interactions, with the antiferromagnetic exchange (2J = 210(1) cm 1 ) between the copper(II) ions within each dinuclear moi- ety dominant over weak interdimer ferromagnetic coupling. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction There has been a resurgence of interest in thiocarbohydrazone and thiosemicarbazone metal chelates, because of their interesting catalytic and magnetic properties, their mimicry of oligonuclearity in metalloproteins [1–3] and also recently because of their poten- tial antimicrobial and antiproliferative activity [4–8]. For the copper chelates, mononuclear [9], dinuclear [10,11], paired dinuclear [5,12] and an octanuclear system [13] have been described. The paired dinuclear compounds entail a face-to-face dimerisation of dinuclear molecules [12]. Following on from our prior work [10,12], we now report a tetranuclear system of linear topology, prepared from a novel Schiff base derived from thiocar- bohydrazide and o-aminobenzaldehyde. Tetranuclear copper(II) molecules are known with cubane [14–18], rectangular [5,19,20] ‘butterfly’ or ‘chair’ (out-of-phase butterfly) [21–23] and linear or pseudo-linear shapes [24,25]. Continuing our work [12] on the coordination chemistry of thio- carbohydrazones, we report here the structure and properties of a tetranuclear copper(II) complex of a new ditopic chelating agent derived from o-aminobenzaldehyde, a molecule itself of enduring interest to inorganic chemists [26–29]. 2. Experimental Thiocarbohydrazide, o-nitrobenzaldehyde, N-allylimidazole and other reagents were used as received (TCI, Sigma–Aldrich, Fisher Scientific). Elemental analyses were from Robertson Microlit, Mad- ison NJ. FAB/LSIMS mass spectra were run on Micromass-VG 70SE and Waters Micromass AutoSpec Ultima instruments (2-nitroben- zyl alcohol matrix), and infrared spectra on a Perkin–Elmer Spec- trum One FT spectrometer furnished with a Universal ATR sampling accessory. Optical spectra were obtained mainly from MeOH solutions using a Perkin–Elmer Lambda-35 spectrophotom- eter. Variable-temperature magnetic susceptibility data were col- lected in the range 2–300 K on a Quantum Design MPMS5S squid magnetometer at 0.1T in DC mode. Background corrections were applied for the sample container assembly, and susceptibility data were corrected for diamagnetism using Pascal’s constants [30]. Co[Hg(SCN) 4 ] was used as a calibration standard, and samples were placed in Al- or gel-capsules in 5 mm polymer straws. Data 0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2010.02.002 * Corresponding authors. E-mail address: ddragancea@gmail.com (D. Dragancea). Inorganica Chimica Acta 363 (2010) 2065–2070 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica