Journal of Chemical Crystallography, Vol. 29, No. 4, 1999 Structure of Ru(acac) 2 (ethoxide)(ethanol)(1/2) trans- stilbene: Intermediate species linked by hydrogen bonds Enrique Mele ´ ndez, (1) * Ilia Guzei, (2) and Arnold L. Rheingold (2) Received September 13, 1998 The reaction of Ru(acac) 3 in ethanol in the presence of zinc and trans-stilbene affords Ru(acac) 2 (EtO)(EtOH) complex, co-crystallized with a half-molecule of trans-stilbene as a by-product, 1. The complex crystallizes in the monoclinic space group P2 1 / n with a = 12.288 (3), b = 28.420(6), c = 13.285 (3) A ˚ ,  = 95.63(3)° and Z = 8. The complex exhibits hydrogen bonds between the two Ru(acac) 2 (EtO)(EtOH) molecules. KEY WORDS: acac = acetylacetonato; hydrogen bonds; trans influence. Experimental section Crystallographic structural determination Crystal, data collection and refinement parame- ters are given in Table 1. The systematic absences in the diffraction data were uniquely consistent for space group P2 1 / n, whose correctness was subse- quently confirmed by chemically reasonable and computationally stable results of refinement. The structure was solved using direct methods, completed by subsequent difference Fourier synthesis and re- fined by full-matrix least-squares procedures. All non-hydrogen atoms were refined with anisotropic displacement coefficients. There are two half- molecules of trans-stilbene located at crystallo- graphic inversion centers and two symmetry indepen- dent molecules of complex Ru(acac) 2 (EtO)(EtOH) in the asymmetric unit. There are two short hydrogen bonds between atoms O(6) UH(A)O(11) and O(12) UHO(5) with OO distances of 2.418 (9) A ˚ and 2.412(8) A ˚ and angles of 175.1(7)° and 170.6(7)°, respectively. (1) Department of Chemistry, University of Puerto Rico Mayaguez Campus PO Box 9019 Mayaguez, Puerto Rico 00681. (2) Department of Chemistry, University of Delaware, Newark, Delaware 19716. * To whom correspondence should be addressed. 399 1074-1542/99/0400-0399$16.00/0  1999 Plenum Publishing Corporation All software and sources of the scattering factors are contained in the SHELXTL (version 5.03) pro- gram library (G. Sheldrick, Siemens XRD, Madi- son, WI). Synthetic details In a 50-mL round bottom flask equipped with a condenser under an atmosphere of nitrogen was charged with 0.50 g of Ru(acac) 3 and 0.3 g of trans- stilbene in 20 mL of ethanol and 1.0 g of zinc. The mixture was refluxed for 6 hr forming a dark-brown slurry. The solvent was removed in vacuo and the residue was extracted with 30 mL of pentane. The volume was reduced to about 7 mL and cooled to -30°C yielding red crystals, ‘‘Ru(acac) 2 (EtO) (EtOH)1/2 (trans-stilbene),’’ 1, and a white powder, Ru(trans-stilbene) in 10% and 45% yield, respec- tively. Infrared data for 1 (KBr): 3080(vw), 3065(vw), 3030(w), 2964(m), 1565(sh), 1550(m), 1517(s), 1447(m), 1382(m), 1262(s), 1097(s), 1023(s), 961(m), 802(s). Results and discussion Tris(acetylacetonato)ruthenium (III), Ru (acac) 3 is a useful precursor for many inorganic and