IridiumeRutheniumegold cluster complexes: Structures, and skeletal Rearrangements Richard D. Adams * , Perry J. Pellechia, Mark D. Smith, Qiang Zhang Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA article info Article history: Received 11 November 2011 Received in revised form 23 December 2011 Accepted 9 January 2012 Keywords: Cluster Trimetallic Gold Iridium Ruthenium abstract Three new IrRuAu trimetallic cluster complexes: IrRu 3 (CO) 13 AuPPh 3 , 1 , HIrRu 3 (CO) 12 (AuPPh 3 ) 2 , 2 and IrRu 3 (CO) 12 (AuPPh 3 ) 3 , 3 were obtained in low yields from the reaction of HIrRu 3 (CO) 13 with [(AuPPh 3 ) 3 O] [BF 4 ]. Compounds 1 and 3 were subsequently obtained in much better yields (82%) and (84%) from the reactions of [AuPPh 3 ][NO 3 ] and [(AuPPh 3 ) 3 O][BF 4 ] with [PPN][IrRu 3 (CO) 13 ], respectively. The molecular structures of all three compounds were established by single crystal x-ray diffraction methods. Compounds 1 and 2 contain an Au(PPh 3 ) group that bridges one triangular face of a tetrahedral IrRu 3 cluster. Compound 2 contains a second Au(PPh 3 ) capping group that bridges an IreRueAu triangle. Compound 3 consists of a pentagonal bipyramidal Au 3 IrRu 3 cluster that has three gold atoms and two of the ruthenium atoms in the equatorial plane. There is a bond between the apical Ir and Ru atoms. Compounds 2 and 3 exhibit dynamical activity in the metal skeleton that leads to a rapid averaging of the inequivalent Au(PPh 3 ) groups on the NMR timescale at room temperature. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Applications for iridium in catalysis continue to grow [1]. Although most catalytic applications are of a homogeneous type [1,2], it has been shown that iridium complexes can also serve as precursors to catalysts that exhibit good activity for the hydroge- nation of aromatics and olefins when placed on supports [3]. Heterogeneous iridium-iron catalysts derived from bimetallic cluster complexes have been shown to exhibit good catalytic activity for the formation of methanol from synthesis gas. [4]. Iridiumeruthenium complexes have been shown to serve as precursors to catalysts for the carbonylation methanol [5]. Sup- ported bimetallic iridiumeruthenium catalysts have been shown to produce C 2 oxygenates from syngas [6] and also to exhibit unusu- ally high catalytic activity for the oxygen evolution reaction in the electrolysis of water [7]. Recently, gold nanoparticles have been shown to exhibit significant catalytic activity for the oxidation of CO and certain olefins [8]. Combining transition metals with gold has led to interesting new bimetallic oxidation nanocatalysts [9]. There have been very few structural characterizations of iridiumerutheniumegold carbonyl cluster complexes [10]. In the course of our studies of the chemistry of [IrRu 3 (CO) 13 ]  [11], we have investigated its reactions with [AuPPh 3 ]NO 3 and [(AuPPh 3 ) 3 O] [BF 4 ]. We have obtained three new iridiumerutheniumegold carbonyl cluster complexes, have established their molecular structures and have investigated their properties in solution. These results are reported herein. 2. Experimental General Data. Reagent grade solvents were dried by the standard procedures and were freshly distilled prior to use. Infrared spectra were recorded on a Thermo Nicolet Avatar 360 FT-IR spectropho- tometer. Room temperature 1 H NMR and 31 P{ 1 H} NMR were recorded on a Bruker Avance/DRX 400 NMR spectrometer oper- ating at 400.3 and 162.0 MHz, respectively. Different temperature 31 P{ 1 H} NMR for compound 3 were recorded on a Varian Mercury 400 spectrometer operating at 161.9 MHz 31 P{ 1 H} NMR spectra were externally referenced against 85% o-H 3 PO 4 . Positive/negative ion mass spectra were recorded on a Micromass Q-TOF instrument by using electrospray (ES) ionization. Ru 3 (CO) 12 and Ir 4 (CO) 12 were obtained from STREM and were used without further purification. HIrRu 3 (CO) 13 [12], [PPN][IrRu 3 (CO) 13 ] [12], [AuPPh 3 ][NO 3 ] [13] and [(AuPPh 3 ) 3 O][BF 4 ] [14] were prepared according to the previously reported procedures. Product separations were performed by TLC in air on Analtech 0.25 silica gel 60 Å F254 glass plates. Dynamic NMR simulations for compound 3 were performed by using the SpinWorks program [15]. The exchange rates were determined at seven different temperatures in the temperature range 60 to þ20  C. The activation parameters were determined from a least- * Corresponding author. E-mail address: Adams@mail.chem.sc.edu (R.D. Adams). Contents lists available at SciVerse ScienceDirect Journal of Organometallic Chemistry journal homepage: www.elsevier.com/locate/jorganchem 0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2012.01.012 Journal of Organometallic Chemistry 706-707 (2012) 20e25