Supported Gold Catalysts Structure and Reactivity of a Mononuclear Gold- Complex Catalyst Supported on Magnesium Oxide** Javier Guzman and Bruce C. Gates* Oxide- and zeolite-supported mononuclear metal complexes are important industrial catalysts, for example, for alkene polymerization, [1] and some have properties not anticipated by known homogeneous catalysis. [2] Some supported transi- tion-metal complexes are close analogues of molecular complexes, with the metal±support-oxygen bonds being as strong as metal±ligand bonds in common transition-metal complexes and strong enough to maintain anchoring during catalysis. [3] Mononuclear gold complexes are used frequently in organometallic chemistry [4] and have been identified as catalysts for reactions including the addition of alcohols to alkynes, [5] asymmetric aldol reactions, [6] C ÀC bond forma- tion, [7] oxidative carbonylation of amines, [8] and selective hydrosilylation of aldehydes. [9] Supported gold catalysts have recently been found to be surprisingly active and selective, for example, for CO oxidation and propene epoxidation. [10] Their unique properties have been variously attributed to the smallness of the gold clusters [10b] and to clusters adjacent to cationic gold species at the support surface. [11] Gold supported 2001, 509±518; f) F. A. Cotton, C. Lin, C. A. Murillo, Acc. Chem. Res. 2001, 34, 759±771. [3] a)R.-D. Schnebeck, E. Freisinger, B. Lippert, Angew. Chem. 1999, 111,235±238; Angew. Chem. Int. Ed. 1999, 38, 168±171; b)R.-D. Schnebeck, E. Freisinger, F. Glahe, B. Lippert, J. Am. Chem. Soc. 2000, 122, 1381±1390. [4] a) H. Rauter, E. C. Hillgeris, B. Lippert, J. Chem. Soc. Chem. Commun. 1992, 1385±1386; b) H. Rauter, E. C. Hillgeris, B. Lippert, J. Am. Chem. Soc. 1994, 116, 616±624; c)J.A.R. Navarro, M.B. L. Janik, E. Freisinger, B. Lippert, Inorg. Chem. 1999, 38, 426±432; d) J. A. R. Navarro, E. Freisinger, B. Lippert, Inorg. Chem. 2000, 39, 2301±2305. [5] a) H. Chen, M. M. Olmstead, D. P. Smith, M. F. Maestre, R. H. Fish, Angew. Chem. 1995, 107, 1590±1593; Angew. Chem. Int. Ed. Engl. 1995, 34, 1514±1517; b) H. Piotrowski, G. Hilt, K. Severin, J.Am.Chem.Soc. 2001, 123,2699±2700;M.-L.Lehaire, R. Scopelliti, H. Piotrowski, K. Severin, Angew.Chem. 2002, 114, 1477±1480; Angew. Chem. Int. Ed. 2002, 41, 1419±1422. [6] a) S.-W. Lai, M. C.-W. Chan, S.-M. Peng, C.-M. Che, Angew. Chem. 1999, 111,708±710; Angew.Chem.Int.Ed. 1999, 38,669± 671; b)P. Chaudhuri, I. Karpenstein, M. Winter, C. Butzlaff, E. Bill, A.X. Trautwein, U. Flˆrke, H.-J. Haupt, J. Chem. Soc. Chem. Commun. 1992, 321±322. [7] M. Fujita, S.-Y. Yu, T. Kusukawa, H. Funaki, K. Ogura, K. Yamaguchi, Angew.Chem. 1998, 110,2192±2198; Angew.Chem. Int. Ed. 1998, 37, 2082±2085. [8] S.-Y. Yu, T. Kusukawa, K. Biradha, M. Fujita, J. Am. Chem. Soc. 2000, 122, 2665±2666. [9] M. Yoshizawa, Y. Takeyama, T. Kusukawa, M. Fujita, Angew. Chem. 2002, 114, 1403±1405; Angew. Chem. Int. Ed. 2002, 41, 1347±1349. [10] 4,7-Phenanthroline is a simple and commercially available ligand that forms a rigid 608 corner, which was previously employed in the self-assembly of a molecular triangle with the linear bipalladium complexes (1808 coordination angle), see: J. R. Hall, S. J. Loeb, G. K. H. Shimizu, G. P. A. Yap, Angew. Chem. 1998, 110,130±133; Angew.Chem.Int.Ed. 1998, 37,121± 123. [11] C. D. Gutsche in Large Ring Molecules (Ed.: J. A. Semlyen), Wiley, New York, 1996, 309 ± 343, and references therein. [12] a) Crystal structure analysis of 1. A single crystal with dimension of 0.25 î 0.15 î 0.05 mm was coated with a sealing material and mounted on a glass fiber. All measurements were made on a Rigaku RAXIS Rapid IP detector equipped with a graphite monochromated Mo Ka radiation source. The data were collected at 293(2) K. The crystallographic molecule contains half a molecule of 1. Crystal data: C 42 H 48 N 18 O 18 Pd 3 ¥2H 2 O, M r = 1448.13; orthorhombic, space group Pmn21, a = 21.8807(4), b = 14.7319(3), c = 23.2315(2) ä, V = 7488.5(2) ä 3 , 1 calcd = 1182kgm À3 . Z = 8, F(000) = 2696, m(Mo Ka ) = 7.68 mm À1 , l = 0.71073 ä. 19837 reflections measured, 7874 observed reflec- tions (I > 2s(I)); number of parameters 648; R 1 = 0.1197; wR 2 = 0.3421. Further refinement was unsuccessful because of the high degree of disorder of the counter anions and the water molecules. b) CCDC-191629 (1) and CCDC-191630 (2) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/ conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB21EZ, UK; fax: (+ 44)1223-336-033; or deposit@ccdc.cam.ac.uk). [13] a) P. A. Gale, Coord. Chem. Rev. 2001, 213, 79 ± 128; b) P. A. Gale, Coord. Chem. Rev. 2000, 199, 181 ± 233; c) A. Bianchi, K. Bowman-James, E. GarcÌa-EspaÊa, Supramolecular Chemistry of Anions , Wiley-VCH, New York, 1997. [14] a) H. Sigel, K. H. Scheller, V. M. Rheinberger, B. E. Fischer, J. Chem. Soc. Dalton Trans. 1980,1022±1028; b) S. Shinkai, K. Araki, O. Manabe, J. Am. Chem. Soc. 1988, 110, 7214±7215. [15] M. Fujita, F. Ibukuro, K. Yamaguchi, K. Ogura, J. Am. Chem. Soc. 1995, 117,4175±4176. [16] Crystal structure analysis of 2. A single crystal with dimension of 0.25 î 0.15 î 0.05 mm was coated with a sealing material and mounted on a glass fiber. All measurements were made on a Rigaku RAXIS Rapid IP detector equipped with a graphite monochromated Mo Ka radiation source. The data was collected at 293(2) K. The crystallographic molecule contains a molecule of 2. Crystal data: C 66 H 48 N 18 O 18 Pd 3 ¥2H 2 O, M r = 1736.40, mono- clinic, space group C2/c, a = 39.366(8), b = 24.887(5), c = 18.217(4) ä, b = 106.69(3)8, V = 17095(6) ä 3 , 1 calcd = 1.544 kgm À3 , Z = 32, F(000) = 8192, m(Mo Ka ) = 0.902 cm À1 , l = 0.71073 ä; 19127 reflections measured, 7704 observed reflec- tions (I > 2s(I)); number of parameters 891; R 1 = 0.0931; wR 2 = 0.2575. [12b] [*] Prof. Dr. B. C. Gates, J. Guzman University of California Davis Department of Chemical Engineering and Materials Science One Shields Ave., Davis, CA95616-5294 (USA) Fax: (+ 1)530-752-1031 E-mail: bcgates@ucdavis.edu [**] This research was supported by DOE BES (FG02-87ER13790). We thank the Stanford Synchrotron Radiation Laboratory (Beamline 4-1), and the National Synchrotron Light Source (Beamline X-11A), both supported by DOE, for beam time. Zuschriften 714 ¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 0044-8249/03/11506-0714 $ 20.00+.50/0 Angew. Chem. 2003, 115, Nr. 6