Influence of the nature of organic components in dinuclear copper(II) pivalates on the composition of thermal decomposition products Irina Fomina a, * , Zhanna Dobrokhotova a , Grygory Aleksandrov a , Artem Bogomyakov b,1 , Matvey Fedin b,1 , Alexander Dolganov c,2 , Tatyana Magdesieva c,2 , Vladimir Novotortsev a , Igor Eremenko a a N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky prosp. 31, 119991 Moscow, GSP-1, Russian Federation b International Tomography Center, Siberian Branch, Russian Academy of Sciences, Institutskaya str. 3a, 630090 Novosibirsk, Russian Federation c Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, GSP-1, Russian Federation article info Article history: Received 8 October 2009 Accepted 11 February 2010 Available online 17 February 2010 Keywords: Copper pivalates Aminopyridine ligands Synthesis X-ray diffraction study Magnetic properties Electrochemical behavior Solid-state thermal decomposition abstract Tetrabridged dinuclear complexes ((2-NH 2 )C 5 H 4 N) 2 Cu 2 (l 2 -OOCCMe 3 ) 4 (2C 6 H 6 ) and ((3-NH 2 )C 5 H 4 N) 2 Cu 2 (l 2 -OOCCMe 3 ) 4 (3) and the cocrystallization product ((4-NMe 2 )C 5 H 4 N) 2 Cu(g 2 –OOCCMe 3 ) 2 2((4- NMe 2 )C 5 H 4 N) 2 Cu 2 (l 2 -OOCCMe 3 ) 4 (4) were synthesized by the reaction of the polymer [Cu(OOCCMe 3 ) 2 ] n (1) with aminopyridine ligands (L) of different nature (Cu: L = 1:1) in C 6 H 6 . The solid-state thermal decomposition of these compounds was studied by differential scanning calorimetry and thermogravi- metry, and their electrochemical behavior was investigated by cyclic voltammetry. All newly synthesized complexes were studied by X-ray diffraction, the magnetic properties of the complexes were investi- gated, and ESR measurements were performed. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, the use of metal complexes as molecular precur- sors for the preparation of nanosized metal particles [1,2] has at- tracted great interest because of the unique physical and catalytic properties [3–5] of such metallic materials. The solid-phase ther- molysis of solutions of complex molecular precursors in suitable matrices [6–10] is used for the synthesis of metals as often as the gas-phase decomposition [1,11] or, for example, the sol–gel tech- nologies [2]. However, the solid-state thermal decomposition of complexes containing metal cations in the absence of external reducing agents differs in that the organic components of precur- sors play an important role in this process. For instance, it is known that metals can easily be generated in the final step of thermal decomposition using complexes with ligands having strong reduc- ing properties. This approach has recently been applied to the ther- molysis of methylhydrazine 3d-metal complexes, which afforded metals or even alloys (in the case of the co-thermolysis of the com- plexes) [12] at rather low temperatures (below 400 °C). Presum- ably, these reactions proceed via the intramolecular reduction of metals with the involvement of ligands having reducing properties. A rise of the temperature leads to a gradual elimination of organic fragments and the clustering of the metal core up to the formation of metal particles. Evidently, these processes essentially depend on the nature of metal ions in the precursors, as well as on the struc- tural and electronic features of both the ligands having a reducing ability and the molecules as a whole. As for the known type of carboxylate complexes, viz., dinuclear tetrabridged d-block metal pivalates LM(l-Piv) 4 ML, where M = Mn(II) [13,14], Fe(II) [15], Co(II) [16–18], Ni(II) [19,20], or Cu(II) [21,22], it can be noted that the pivalate ligand (Piv = (CH 3 ) 3 CCO 2  ) is a potential reducing agent with respect to metal ions be- cause it contains a large number of C–H bonds. However, it ap- peared that the nature of the metal ions, as well as the axial ligand, also play an important role. For example, the solid-phase thermolysis of dinuclear manganese and iron pivalates (M = Mn and Fe) did not afford metals in spite of the presence of strong reducing agents (aminopyridine ligands) as the ligands L [23]. On the other hand, the thermolysis of tetrabridged dinuclear com- plexes with nickel atoms sometimes afforded a metallic phase [24]. In the present study, we focused on the influence of the nature of the ligands L on the phase composition of thermolysis products and investigated the electrochemical behavior of a series of dinu- clear copper pivalates LCu(l-Piv) 4 CuL (L is substituted pyridine). The results of this study allow the evaluation of the pathways of the transformations of these molecules in the course of thermal re- dox processes. 0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2010.02.021 * Corresponding author. Tel.: +7 (495) 955 4835; fax: +7 (495) 952 1279. E-mail address: fomina@igic.ras.ru (I. Fomina). 1 Fax: +7 (383) 333 1399. 2 Tel.: +7 (495) 939 3065; fax: +7 (495) 932 8846. Polyhedron 29 (2010) 1734–1746 Contents lists available at ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly