Functionalised b-diketone assisted self-assembly of a hexanuclear yttrium oxo-hydroxo cluster Ananda Kumar Jami, Pilli V.V.N. Kishore, Viswanathan Baskar * School of Chemistry, University of Hyderabad, Hyderabad 500046, India article info Article history: Received 9 March 2009 Accepted 12 April 2009 Available online 6 May 2009 Keywords: Yttrium clusters Self-assembly Functionalised b-diketones Oxo-hydroxo bridges Synthesis and structural elucidation abstract The reaction of YCl 3 Á6H 2 O with ortho-hydroxydibenzoylmethane (HO-DBMH) in a 1:2 ratio, in methanol and in the presence of excess triethylamine as a base yielded a yellow precipitate which on crystallization from toluene or benzene /hexane afforded pale yellow block-like crystals. Single crystal X-ray diffraction of 1 revealed the formation of an interesting hexanuclear yttrium oxo-hydroxo cluster [Y 6 (O-DBM) 6 (HO- DBM) 4 (l 3 -OH) 2 (MeOH) 4 ]; the core resembles a butterfly framework flanked by a lanthanide atom on each side. Ten phenolic b-diketone ligands are present in the cluster, which bridge the metal centers in both chelating and chelating-bridging fashions. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Multinuclear metal clusters, in particular lanthanide based clus- ters, have generated a huge amount of interest in recent years ow- ing to their wide ranging applications from precursors to magnetic materials to catalysis [1–13]. Traditionally, lanthanide oxo-hydro- xo clusters have been synthesized either by controlled hydrolysis of air and moisture sensitive lanthanide precursors [14–16] or by slow deprotonation of the coordinated water molecules of hydra- tion in lanthanum salts like LnCl 3 ÁxH 2 O, in the presence of suitable ligands by addition of a base [17–19]. b-Diketones have been used as ligands extensively to synthesize a large number of lanthanide clusters whose solid state structures vary from tetra- to tetra deca- nuclear forms [17–23]. Although b-diketones have been investi- gated in detail for their ligating ability towards lanthanides and their solid state structures are well understood, the use of func- tionalized b-diketones [24] and in particular phenolic b-diketones [25,26] as ligands towards lanthanides are rare. In this paper, we present the synthesis and structural characterization of a hexanu- clear cluster of yttrium and using HO-DBMH as a ligand. The single crystal X-ray characterization technique revealed the formation of a novel hexanuclear yttrium cluster, [Y 6 (O-DBM) 6 (HO-DBM) 4 (l 3 - OH) 2 (MeOH) 4 ](1). 2. Experimental Yttrium trichloride hexahydrate was synthesized from the cor- responding oxide by neutralizing with conc. HCl, followed by evap- oration to dryness. The ligand 1-(2-hydroxyphenyl)-3-phenyl-1,3- propanedione was prepared according to the literature method [27]. Triethylamine and the solvents were used as purchased from commercial sources without further purification. Elemental analy- ses were carried out with a FLASH EA series 1112 CHNS analyzer. IR spectra were recorded on a JASCO-5300 FT-IR spectrophotometer (using KBr pellets). The 1 H solution NMR spectrum was recorded on a BRUCKER DRX 400 instrument. Single crystal X-ray data was collected at 298(2) K on a BRUKER SMART APEX CCD area detector system [k(Mo Ka) = 0.71073 Å] with a graphite monochromator, and the data were reduced using SAINTPLUS. The structure was solved using SHELXS-97 and refined using SHELXS-97 [28,29]. All non hydro- gen atoms were refined anisotropically, except for the carbon and oxygen atom of a methanol solvent molecule (C 81 –O 32 ) which was refined isotropically. As the solvents of crystallization, metha- nol and water molecules, were heavily disordered, the hydrogen atoms were not fixed for the solvents of crystallization found in 1. 2.1. Synthesis The ligand, 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione (H0-DBMH) (0.470 g, 1.96 mmol) and YCl 3 Á6H 2 0 (0.30 g, 0.98 mmol) were dissolved in methanol (20 ml). Triethylamine (0.39 g, 3.92 mmol) was slowly added to the above reaction mix- ture and stirred for 12 h at room temperature. The pale yellow pre- cipitate that formed was filtered, washed with methanol (5 ml) 0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2009.04.035 * Corresponding author. Tel.: +91 40 66794825; fax: +91 40 23012460. E-mail addresses: vbsc@uohyd.ernet.in, baskarviswanathan@gmail.com (V. Baskar). Polyhedron 28 (2009) 2284–2286 Contents lists available at ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly