Synthesis, properties and extended MS studies of a new heterometallic [Mn 4 Ni 2 ]-core oxime-bridged complex Lukasz Szyrwiel a,b,⇑ , Justyna Brasun ´ c , Zbigniew Szewczuk d , Małgorzata Hołyn ´ ska e,⇑ a Department of Chemistry of Drugs, Wrocław Medical University, ul. Tamka 1, 50-137 Wrocław, Poland b CNRS/UPPA, LCABIE, UMR5254, Hélioparc, 2 av. Pr. Angot, F-64053 Pau, France c Department of Inorganic Chemistry, Wrocław Medical University, ul. Szewska 38, 50-139 Wrocław, Poland d Department of Chemistry, Wrocław University, F. Joliot Curie 14, 50 383 Wrocław, Poland e Fachbereich Chemie and Wissenschaftliches Zentrum für Materialwissenschaften, Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35043 Marburg, Germany article info Article history: Received 3 November 2012 Accepted 21 December 2012 Available online 29 December 2012 Keywords: Heterometallic complexes Synthesis Crystal structures ESI-MS studies MS/MS experiment Properties abstract Synthesis and properties of a new [Mn 4 Ni 2 O 2 (sao) 6 (CH 3 OH) 6 ]1.3H 2 O4.4CH 3 OH (1) compound are reported (saoH 2 = salicylaldoxime). The complex core displays two oxime-bridged [Mn III 2 Ni II l 3 –O] trian- gular units. The presence of Mn/Ni sites is confirmed by EDX/elemental analyses, extended MS spectrom- etry studies and X-ray crystallography. MS/MS analyses are shown for the selected ions. Preliminary results for other properties of 1 (EPR, IR, preliminary studies of magnetic properties) are also presented. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Mixed-transition metal heterometallic complexes are an estab- lished part of the chemistry of new magnetic materials with oxi- mes acting as ligands linking metal ions [1]. In particular, Mn–Ni oxime-bridged compounds are known from studies on oligomeric units [2], such as trinuclear Mn III –Ni II –Mn III Single Molecule Magnets [2a] or tetranuclear Ni II –Mn II 2 –Ni II complexes [2b]. The units can be assembled into polymeric chains being single chain magnets [3]. A family of higher-nuclearity Mn III /Ni II clusters, displaying SMM behavior, was reported by Chen et al. [4]. Oxime-bridged heterometallic complexes of Mn with other transi- tion metals, e.g. Zn(II) [5] are also known. In this paper we contribute a new example of an Mn III –Ni II metallacrown assembly (1) with complex [Ni II 2 Mn III 4 ] core related to a well-known class of oxime-bridged [Mn 6 O 2 ] compounds [6]. It is unreliable to distinguish between manganese and nickel sites solely based on X-ray diffraction analysis for a product crystallizing from a mixture of starting materials obtained in situ. However, in the case of crystalline 1 the presence of an [Mn 4 Ni 2 ] core is supported by other methods, in particular EDX and an ex- tended MS analysis. These methods give the first unambiguous hint on the presence of Mn and Ni at 2:1 ratio, which is then used for the interpretation of the X-ray diffraction data. The information on structure of the related metallacrown com- plexes in solution is of special importance [7]. An efficient strategy to describe such properties as stability/dynamics in solution is the application of mass spectrometry [8–12] and MS/MS methods [8]. In particular, extended MS studies carried out for 1 may be helpful in the analysis of the related compounds and are an important aim of this work. 2. Experimental 2.1. General HPLC-purity methanol was used. Tetraethylammonium hydrox- ide (25% solution in methanol) was purchased from Aldrich and kept under Ar atmosphere. MnCl 2 4H 2 O, salicylaldoxime and Ni(NO 3 ) 2 6H 2 O were purchased and used as received. These chemicals were used without further purification. 2.2. Synthesis 0.198 g (1 mmol) of MnCl 2 4H 2 O and 0.137 g (1 mmol) of salicyl- aldoxime were combined in 75 ml of methanol. Two milliliters of tetraethylammonium hydroxide solution in methanol was added, resulting in darkening of the resulting solution. After 30 min stirring 0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.poly.2012.12.017 ⇑ Corresponding authors. E-mail addresses: lukasz.szyrwiel@am.wroc.pl (L. Szyrwiel), holynska@chemie. unimarburg.de (M. Hołyn ´ ska). Polyhedron 51 (2013) 90–95 Contents lists available at SciVerse ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly