Synthesis and First Separation of Chiral TrimetalCarbonyl Clusters containing an RuCoMo(m3-S) CoreEr-Run Ding,a Qing-Shan Li,a Yuan-Qi Yin*a and Jie SunbaState Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute ofChemical Physics, Chinese Academy of Science, Lanzhou 730000, ChinabShanghai Institute of Organic Chemistry, Chinese Academy of Science, Shanghai 200032, ChinaClusters RuCoMo(3-S)(CO)8C5H4R [R HC(O) 2, MeC(O) 3, PhC(O) 4, MeOC(O)C6H4C(O) 5] were obtained bythe reaction of (3-S)RuCo2(CO)9 1 and [M(CO)3RC(O)Cp]£¾, clusters 3 and 5 have been solved by single crystalX-ray diffraction and cluster 3 was resolved on amylopection tris(phenylcarbamate) (ATP) chiral stationary phases(CSPs).Transition-metal cluster compounds are currently underintensive scrutiny because of their potential catalytic appli-cations, both as models for understanding catalytic metalsurfaces1 and as catalysts in their own right.3 Our interest inthe reactivity of chiral clusters prompted us to prepare tetra-hedral skeleton complexes containing RuCoMoS cores andto nd a good method of resolution of enantiomers byliquid chromatography on CSPs.Reuxing a solution of NaMo(CO)3(C5H4)R [R HC(O),MeC(O), PhC(O), MeOC(O)C6H4C(O)] with cluster 1 inTHF gave clusters 2¡Ó5 in moderate yield (Scheme 1).Reduction of cluster 3 by NaBH4 in methanol at roomtemperature gave cluster 6.The IR spectra of all clustersexhibited a large number of absorption bands between 1856and 2087 cm£¾1, which were assigned to terminal carbonylvibrations.The spectra of the cluster 6 revealed OH absorp-tion peaks at 3383 cm£¾1. These results are consistent withthe reduction of the C.O groups (1686 cm£¾1) in cluster 3 bythe action of NaBH4.The structures of clusters 3 and 5 were determined byX-ray structure analysis and crystal data are collected inTable 1. The structure of cluster 3 unexpectedly revealsthe presence of two isomeric molecules A and B in the unitcell (Fig. 1). Each unit displays a RuCoMoS tetrahedralgeometry. The acute angles in the tetrahedral core of cluster3 about the basal atoms range from 50.12 to 64.098, andthose about the sulfur atom average 73.468, which deviateconsiderably from perfect tetrahedral geometry. This resultsbecause the metal¡Ómetal bonded RuCoMo triangle restrictsthe angles around the sulfur atom. The distances from thesulfur atom to the metal are not equal [Ru¡ÓS 2.330(3) A ,Mo¡ÓS 2.37692) A , Co¡ÓS 2.205(3) A ].The Ru¡ÓS bondlength is roughly equal to that in a known complexHRu3(CO)9[(m2-S)Mo(CO)3(NCMe)2] (Ru¡ÓS 2.334 A ) butis shorter than that found typically.11 Cluster 5 contains atetrahedral skeleton formed by Ru, Co, Mo and S, theslightly distanced triangular Ru¡ÓCo¡ÓMo moiety beingcapped by a sulde ligand as in cluster 3 (Fig. 2. The dis-tance of the Mo atom to the Cp ring center is 1.992 A .Treating m3-S as a four-electron donor and the cyclopenta-dienyl group as a ve-electron donor, cluster 5 contains atotal of 48 valence electrons and is electronically saturated.J.Chem. Research (S),1998, 624¡Ó625J. Chem. Research (M),1998, 2601¡Ó2657Table 1 Summary of crystal and intensity data for complexes 3 and 5Complex 3 5Formula C15H7O9SRuCoMo C22H11O11SCoRuMoMw 619.22 739.11Crystal system Orthorhombic TriclinicSpace group Pbca P1a/A 26.229(7) 8.174(3)b/A 18.200(6) 19.454(4)c/A 15.929(4) 8.042(3)a/8 92.78(2)b/8 108.74(3)g/8 88.73(1)Z 8 2V/A 3 7604(6) 1209.5(7)Dc/g cm£¾3 2.163 2.030l/A 0.71069 0.71069T/8C 20 20m(moKa) cm£¾1 24.51 19.51F(000) 4768.00 720.00No observations [I > 3.00s(I)] 3343 2674Total no.reflections 4883 3861Residuals: R, Rw 0.033, 0.045 0.056, 0.074Scheme 1*To receive any correspondence (e-mail: hcom@ns.lzb.ac.cn).624 J. CHEM. RESEARCH (S), 1998In our attempts to separate the enantiomers of 3 we found that a general separation procedure did not apply. However, an enantiomer separation via chromatography over an optically active adsorbent was successful.The chiral ability of the CSP depends on the thickness of the coating. Usually, the greater the amount of chiral agent, the better the chiral discrimination. For coated cellulose CSP, Okamoto et al.12 chose a coating of ca. 20¡¾25 mass%. However, we found that this level resulted in low optical resolution on the 25 mass % ATP-coated phase; a coating of 15 mass % appeared to be optimal. This indicates that it is important to reduce non-chiral interactions with Si¡¾OH or ¡¾NH2 groups by a well distributed and ordered coating and overloading may destroy this characteristic. Fig. 3 shows the chromatogram of 3 on a 15 mass % coated phase. We are grateful to the Laboratory of Organometallic Chemistry at Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences for the ¢çnancial support of our work. Techniques used: 1R, 1H NMR, MS, HPLC Table 2: Atomic coordinates and Biso/Beq for cluster 3 Table 3: Atomic coordinates and Biso/Beq for cluster 5 Table 4: Selected intramolecular distances (AE ) and bond angles (8) for cluster 3 Table 5: Selected intramolecular distances (AE ) and bond angles (8) for cluster 5 Table 6: The e€ects of propan-2-ol concentration on the resolution References: 18 Appendix: Crystallographic data for cluster 3 and 5 Received, 19th February 1998; Accepted, 15th June 1998 Paper E/8/01418C References cited in this synopsis 1 G.Su E ss-Fink, Angew. Chem., 1994, 104, 71. 3 J. R. Shapley, Strem Chem., 1978, 6, 3. 11 L. A. Hoferkamp, G. Rhenwald, H. Stoeckli-Evans and G. Suss- Fink, Organometallics, 1996, 15, 704. 12 Y. Okamoto, K. Hatada, T. Shibata, I. Okamato, H. Namikoshi and Y. Yuki, Eur. Pat. Appl., 1984, EP 147804. Fig. 1 Crystal structure of cluster 3 Fig. 2 Crystal structure of cluster 5 Fig. 3 The chromatograms of resolution of the cluster 3 on a 15% ATP-coated column Mobile phase: hexane¡¾propan-2- ol a 95:5 (v/v); Flow rate: 0.5 ml min¢§1; 0.02 AUF J. CHEM. RESEARCH (S), 1998 625