Halo and azido copper(II) coordination polymers featuring the gem-diolate forms of di-2-pyridyl ketone Harikleia Sartzi a , Giannis S. Papaefstathiou b , Vassilis Psycharis c , Albert Escuer d , Spyros P. Perlepes a , Constantinos C. Stoumpos a,d, * a Department of Chemistry, University of Patras, 26504 Patras, Greece b Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771 Zografou, Greece c Institute of Materials Science, NCSR ‘‘Demokritos”, 15310 Aghia Paraskevi Attikis, Athens, Greece d Departament de Quimica Inorganica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain article info Article history: Available online 11 June 2009 Keywords: Copper(II) complexes Crystal structures Di-2-pyridyl ketone Magnetic properties One-dimensional coordination polymers abstract The reactions of di-2-pyridyl ketone, (py) 2 CO, with [Cu 2 (O 2 CMe) 4 (H 2 O) 2 ] in the presence of NaN 3 , HCl and HBr have led to the isolation of complexes {[Cu 8 {(py) 2 CO 2 } 4 (N 3 ) 6 (O 2 CMe) 2 ]2MeCNH 2 O} 1 (12MeCNH 2 O), [Cu 2 {(py) 2 C(OH)O}Cl 3 ] 1 (2) and [Cu 2 {(py) 2 C(OH)O}Br 3 ] 1 (3), respectively, where (py) 2 CO 2 2 and (py) 2 C(OH)O  are the dianion and the monoanion of the gem-diol form of (py) 2 CO. Complex 12MeCNH 2 O is an 1D coordination polymer consisting of centrosymmetric [Cu 8 {(py) 2 CO 2 } 4 (N 3 ) 6 (O 2 CMe) 2 ] cluster units linked through weakly coordinated azido bridges. The (py) 2 CO 2 2 groups adopt the g 1 :g 2 :g 2 :g 1 :l 4 coordination mode, while the N 3  ions behave as g 2 :l and g 1 : g 2 :l 3 ligands. The isostructural compounds 2 and 3 are also 1D coordination polymers consisting of {Cu 2 {(py) 2 C (OH)O}X 3 } 2 units (X=Cl, Br) linked through double halo bridges. The (py) 2 C(OH)O - ligand adopts the tri- dentate, bis-chelating g 1 :g 2 : g 1 :l mode. A common feature in the three complexes is the presence of interchain H-bonding interactions which result in the formation of 2D networks. The magnetic properties of 1–3 have been studied by variable-temperature dc magnetic susceptibility and variable-field magne- tization techniques. The analyses of the magnetic data were performed taking into account only the dom- inant exchange interactions within dinuclear subunits. The intradinuclear exchange interactions have been found to vary from strongly and moderately antiferromagnetic in 1 to ferromagnetic in 2 and 3. This work demonstrates the flexibility, versatility and synthetic potential of combining (py) 2 CO with carbox- ylate and azido or halo ligands. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction The coordination chemistry of Cu II has been significantly devel- oped in the last four decades for a variety of reasons. From the bio- inorganic chemistry viewpoint, the modeling of active sites in Cu biomolecules has been pursued [1], while from the magnetochem- istry viewpoint dinuclear complexes have been synthesized in or- der to create magnetostructural correlations [2] and trinuclear complexes have attracted interest in order to study spin frustration and antisymmetric exchange phenomena [3], as well as for the ra- tional synthesis of ferromagnetic entities [4]. Infinite lattices con- stitute another well-studied class of Cu II compounds leading to construction of 1D, 2D and 3D architectures [5], while Cu II polyme- tallic complexes with esthetically pleasing structures and interest- ing magnetic properties are also a ‘‘hot” topic in contemporary coordination chemistry [6]. Our interest focuses on the synthesis of polymetallic Cu II com- plexes using di-2-pyridyl ketone, (py) 2 CO (Scheme 1), as an organic ligand. The special characteristic of this organic molecule is the susceptibility of its ketone group towards nucleophilic attack. Sev- eral nucleophiles have been used aiming at the in situ transforma- tion of the (py) 2 CO ligand, but H 2 O is by far the most interesting nucleophile since it produces the gem-diolate (1 or 2) forms of the ligand (Scheme 1) which have increased potential for the assembly of polynuclear species compared with other nucleo- phile-based, transformed derivatives of the ligand. The Cu II chem- istry of (py) 2 CO is already well studied having produced Cu 2 [7], Cu 4 [8], Cu 6 [9], Cu 7 [10], Cu 8 [11], Cu 11 [12] and Cu 12 [10] polynu- clear species featuring the gem-diolate forms (py) 2 C(OH)O  and (py) 2 CO 2 2 and some polymeric species based on polymerization of discrete {Cu 2 } subunits [13]. Compounds bearing the hemiketa- late form of the ligand have also been reported, but these com- pounds are limited to Cu 2 [14], Cu 4 [15] and polymeric species 0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2009.06.016 * Corresponding author. Address: Department of Chemistry, University of Patras, 26504 Patras, Greece. Tel.: +30 2610 996019; fax: +30 2610 997118. E-mail address: kstoump@upatras.gr (C.C. Stoumpos). Polyhedron 29 (2010) 100–109 Contents lists available at ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly