Aryldiazenido ruthenium(II) complexes. Structure and characterization of p-tolyldiazenido carbonyl-ruthenium(II) coordination compound and its reaction with pyrazole and pyridine Jan G. Małecki a,⇑ , Anna Maron ´ a , Tadeusz Gron ´ b , Monika Oboz b a Department of Crystallography, Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice, Poland b Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland article info Article history: Received 15 March 2014 Accepted 4 June 2014 Available online 12 June 2014 Keywords: Ruthenium p-tolyldiazenido coordination compounds Carbonyl ruthenium pyrazole and pyridine coordination compounds X-ray Magnetic properties UV–Vis spectra abstract The p-tolyldiazenido ruthenium [RuCl 2 (CO)(PPh 3 ) 2 (N 2 PhCH 3 )] (1) and [RuCl 2 (CO)(PPh 3 ) 2 (HPz) 2 ](2) and [RuCl 2 (CO)(PPh 3 )(py)] (3) coordination compounds were synthesized and characterized by IR, 1 H, 13 C, 31 P NMR, electronic absorption and X-ray crystallography. The structural parameters showed the bent coordination mode of N 2 PhCH 3 ligand in complex (1) but the measured magnetic susceptibility showed a week response to the ac applied magnetic field and a lack of a Curie–Weiss region means diamagnetism. The most spectacular observation concerns the ZFC-FC splitting, however, the product vT versus temper- ature T is revealing none to the anomaly. The reactions of (1) with pyrazole and pyridine lead to mono- phosphine complexes so it may be used as a precursor for the synthesis of the new monophosphine carbonyl ruthenium coordination compounds(II). Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Recently the p-tolyldiazenido ruthenium(II) coordination com- pound with formula [RuCl 3 (PPh 3 ) 2 (N 2 PhCH 3 )]CH 3 OH and the com- plexes with pyrazole and imidazole ligands with general formula [RuCl 3 (PPh 3 )(N 2 PhCH 3 )(L)] have been reported [1]. As a continua- tion of previous research the phosphine carbonyl ruthenium coor- dination compound with p-tolyldiazenido ligand with formula [RuCl 2 (CO)(PPh 3 ) 2 (N 2 PhCH)] has been synthesized. The coordina- tion mode of azo nitrogen to transition or non-transition metal ions is well documented [2–12] but most of the ligands containing azo nitrogen are multidentate (bi- or tridentate). Significant prop- erty of the azo type ligands due to presence of the –N@N– group is that it may lead to the stabilization of low valent metal oxidation states. It is caused by its p acidity and presence of low lying azo- centered p / -molecular orbitals [13,14]. Moreover the ability of transition metals to stabilize through coordination otherwise unstable species is especially evident for aryldiazenido/aryldiazene complexes. Research on the p-tolyldiazo complexes, especially ruthenium ones, concern the coordination geometries of diazo ligand and its similarity to nitrosyl group. The isoelectronic nature of NO + and ArN 2 + moiety allows assuming that the coordinated aryl- diazonium cation may also exhibit duality of bonding modes. It can be characterized as either linear or bent M–N–N structural units, shown in scheme below: M N N Ar N N Ar M M N N Ar Ia Ib II Based on crystallographic evidences it can be concluded that for describing the linear mode of bonding, Ib unit is clearly more important than unit Ia. Similar studies extended by dynamic behavior of aryldiazenido ligands in half sandwich ruthenium(II) complex have been published in 2000 [15]. In the CSD base is noticed only one ruthenium phosphine car- bonyl complex with phenyldiazene ligand with formula [RuCl(CO) 2 (HN 2 Ph)(PPh 3 ) 2 ]ClO 4 CH 2 Cl 2 reported in 1975 year [16]. Haymore and Ibers did not examined the reactions of the complex with other ligands (except the reactions with non-coordinated acids) and focused only on the spectroscopic studies. It is true that has been mentioned that this type of coordination compound may undergo to the ligand exchange reaction with the removal of diazen- ido ligand but no experimental examples were given. We perform the reactions of the [RuCl 2 (CO)(PPh 3 ) 2 (N 2 PhCH)] complex with pyrazole and pyridine and it was found that the http://dx.doi.org/10.1016/j.poly.2014.06.014 0277-5387/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +48 323591627. E-mail addresses: gmalecki@us.edu.pl (J.G. Małecki), Tadeusz.Gron@us.edu.pl (T. Gron ´ ). Polyhedron 81 (2014) 196–202 Contents lists available at ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly