Reactivity of the osmium antimony cluster Os3(CO)10(MU H)(MU sbph2) with some group 16 compounds

REACTIVITY OF THE OSMIUM-ANTIMONY CLUSTER Os3(CO)10(µ-H)(µ-SbPh2) WITH SOME GROUP 16 COMPOUNDS TAN WEN LING B.Sc.(Hons.), UM A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE 2010 Acknowledgements First of all, I would like to thank my supervisors, A/P Fan Wai Yip, A/P Leong Weng Kee and A/P Richard Wong Chee Seng for their patient guidance and invaluable advice throughout the project. Next, I would like to thank all the members of the groups. In particular, I would like to express my gratitude to Seah Ling, Kien Voon, Garvin, Xue Ping, Rakesh, Boon Ying and Kai Ning, for their help, support and fruitful discussions. I am also grateful to all the staff in the instrument labs for making data acquisition possible. Last but not least, I would like to thank my lovely family members for their prayers and motivation support that made the project complete. i TABLE OF CONTENTS Acknowledgements i Table of Contents ii Abstract iv Molecular Numbering Scheme v Abbreviations xi List of Tables xii List of Figures xiii List os Schemes xiv Chapter 1: Organometallic chemistry of clusters containing osmium or ruthenium and the heavier group 15 elements p.1 1.1. Structural feature p.2 1.2. Reactivity p.9 1.3. References p.13 Chapter 2: Results and discussion p.16 2.1. Reaction of Os3(CO)10(µ-H)(µ-SbPh2) with REER and PhEH p.16 2.2. Conclusion p.27 2.3. References p.28 Chapter 3: Experimental p.29 3.1. General experimental p.29 3.2. Reaction of [PPN][HOs3(CO)11] with (p-tolyl)2SbCl p.30 3.3. Reaction of 1 or 2 with REER or REH (R = ph, Me; E = S, Se, Te) p.30 ii 3.4. Reaction of clusters 5 p.33 3.4.1. Thermolysis of 5b p. 33 3.4.2. Reaction of 5b with PPh3 p.33 3.4.3. Reaction of 5c with bromine p.34 3.5. Crystallography studies p.35 3.6. References p.37 Chapter 4: d-f block organometallic clusters p.38 4.1. Background p.38 4.2. Synthetic strategy p.39 4.3. Synthesis of organometallic clusters containing transition metal- lanthanide bonds p.41 4.4. Experimental p.43 4.4.1. General experimental p.43 4.4.2. Synthesis of Os3(CO)11L, [L = Ph2P(CH2CH2C9H7), Ph2P(OC4H3)] p.44 (a) Synthesis of Os3(CO)11[P(CH2CH2C9H7)Ph2], 13 p.44 (b) Synthesis of Os3(CO)11[P(OC4H3)Ph2], 14 p.44 4.4.3. Reaction of Cp*2Sm(THF)2 with 13 or 14 p.45 (a) Reaction with Os3(CO)11[P(CH2CH2C9H7)Ph2], 13 p.45 (b) Reaction with Os3(CO)11[P(OC4H3)Ph2], 14 p.45 4.4.4. Synthesis of (THF)Yb[(C9H7CH2CH2)PPh2]3, 15 p.45 4.4.5. Reaction of (THF)Yb[(C9H7CH2CH2)PPh2]3 with Os3(CO)11(NCMe) p.46 4.5. References Appendices p.47 CDROM iii ABSTRACT The reaction of the osmium-antimony cluster Os3(CO)10(µ-H)(µ-SbPh2) with the group 16 compounds REER or PhEH (R = Ph, Me; E = S, Se, Te) led to the isolation of the compounds Os3(CO)10(µ-H)(µ-SER) and Os3(CO)10(µ-SbPh2)(µ-EPh). However, the as-yet unidentified major products were yellow powders which contained a 2:1 ratio of ER and SbPh2. iv MOLECULAR NUMBERING SCHEME The short line extending from Os (in the molecular structure diagrams) represents a coordinative bond from carbon monoxide to osmium (Os-CO). 1. Os3(CO)10(µ-H)(µ-SbPh2) SbPh2 Os H Os Os 2. Os3(CO)10(µ-H)[µ-Sb(p-OCH3C6H4)2] Sb(p-tolyl)2 Os H Os Os 3a. Os3(CO)10(µ-H)(µ-SPh) SPh Os H Os Os 3b. Os3(CO)10(µ-H)(µ-SePh) SePh Os H Os Os v 3c. Os3(CO)10(µ-H)(µ-TePh) TePh Os H Os Os 4a. Os3(CO)10(µ-SbPh2) (µ-SPh) Os SbPh2 Os Os S Ph 4b. Os3(CO)10(µ-SbPh2) (µ-SePh) Os SbPh2 Os Se Ph Os 5a. 5b. 5c. Unknown compounds from reaction of 1 or 2 with REER or REH 5d. (R = Ph, Me, p-tolyl; E = S, Se, Te) 5e. 6. Unknown compounds from reaction of 5b with PPh3 7. 8. 9. Unknown compounds from reaction of 5b with bromine 10. vi 11. Os3(CO)11(NCCH3) Os Os Os H3CCN 12. Cp*2Sm(THF)2 THF Sm THF 13. Os3(CO)11[P(CH2CH2C9H7)Ph2] Os Os Os 14. P(CH2CH2C9H7)Ph2 Os3(CO)11[P(OC4H3)Ph2] Os Os Os 15. P(OC4H3)Ph2 (THF)Yb[(C9H7CH2CH2)PPh2]3 Yb O PPh2 3 vii 16. Unknown compounds from reaction of 11 with 15 A. Os3(CO)10(µ-SbPh2)2 Os SbPh2 Os Os Sb Ph2 B. [Os3(CO)10(µ-SbPh2)2]2 Ph2 Sb Os Os Os H H Os Os Os Sb Ph2 C. HOs3(CO)10(µ-SbPh2)L, L = EPh3, CO or tBuNC H Os Os SbPh2 Os L D. HOs3(CO)10(µ-SbPh2)L H Os Os SbPh2 Os L viii E. HOs3(CO)10(µ-SbPh2)L H Os Os SbPh2 Os L F. Os3(CO)9(µ-H)(µ-SbPh2)(AsPh3) SbPh2 Os H Os Ph3As G1. Os Os3(CO)10(µ-ER)2, E = S, Se or Te Os ER ER Os Os G2. Os3(CO)10(µ-ER)2 Os ER Os E R Os ix H. HOs3(CO)10(µ-SbPh2)( R2E2) or HOs3(CO)10(µ-SbPh2)(REH), R = Ph or Me; E = S, Se or Te H Os Os SbPh2 Os E ER or H R x Abbreviations EA Elemental Analyses ESI Electrospray Ionization FAB Fast Atom Bombardment IR Infrared Q-Tof Quadrupole Time-of-Flight MS Mass Spectrometry NMR Nuclear Magnetic Resonance ORTEP Oak Ridge Thermal Ellipsoid Plot THF Tetrahydrofuran TLC Thin Layer Chromatography xi LIST OF TABLES Table 1.1 Known EM clusters (M = Ru, Os; E = As, Sb, Bi). p.3 Table 1.2 Ranges of the M-E bond lengths. p.8 Table 2.1 Selected bond lengths (Å) and angles (°) for 4a, 4b, 4e and 4f. p.21 Table 2.2 IR spectra and 1H NMR spectra of compounds 5. p.23 Table 3.1 Amount of reactants, reaction time and the reaction products. p.31 Table 3.2 Spectroscopic data of the reaction products. p.32 Table 3.3 Crystallographic table for clusters 4a and 4b. p.36 xii LIST OF FIGURES Figure 2.1 Infrared spectrum (in hexane) of Os3(CO)10(µ-H)(µ-SPh), 3a. p.17 Figure 2.2 Infrared spectrum (in hexane) of Os3(CO)10(µ-SbPh2)(µSPh), 4a. p.18 Figure 2.3 ORTEP diagram for 4a. p.20 Figure 2.4 IR spectra (in CH2Cl2) of compounds 5c. p.24 Figure 2.5 1 H NMR (500 MHz, CDCl3) of compounds 5c. p.25 Figure 2.6 1 H NMR (500 MHz, CDCl3) spectrum of compound 5e. p.26 Figure 2.7 Variable temperature 1H NMR (400 MHz, d8-toluene) of 5e (Top: 80°C; middle: 22°C; bottom: -80°C). p.26 Figure 4.1 Organometallic compounds that contain Ln-M bond. p.39 xiii LIST OF SCHEMES Scheme 1.1 Preparation of cluster 1. p.10 Scheme 1.2 Reaction of 1 with nucleophiles. p.11 Scheme 1.3 Reaction of triosmium clusters and R2E2 (R = Ph or Me; E = S, Se or Te). p.12 Scheme 2.1 Reaction of Os3(CO)10(µ-H)(µ-SbPh2) with REER and REH. p.16 Scheme 2.2 Proposed reaction scheme for the formation of 4a and 4b. p.22 Scheme 4.1 Synthesis of organometallic clusters containing Ln-M bonds through ligand assistance. p.40 Scheme 4.2 Synthesis of organometallic clusters containing Ln-M bonds through ligand assistance. p.41 Scheme 4.3 Synthetic scheme. p.42 xiv Chapter 1 Organometallic chemistry of clusters containing osmium or ruthenium and the heavier group 15 elements Organometallic clusters are compounds with two or more metal atoms in which metal-metal bonding is present.1 Beginning from the 1970s, numerous novel clusters have been reported every year.2 The initial stimulus was the cluster-surface analogy, i.e., a metal cluster may serve as a structural model for the interaction of organic ligands on the surface of bulk metal. The gradual evolution of cluster structure, magnetic behavior, and ionization potential with increasing cluster size is another reason for the interest in cluster compounds. When several transition metal atoms bind together, they tend to agglomerate in order to form the maximum number of metal-metal bonds, instead of forming chains. 3 Main group-transition metal cluster compounds have been of great interest in the field of organometallic chemistry due to their unique structural and reactivity patterns. The introduction of main group elements into a transition metal cluster framework enhances its polarity and changes the reactivity chemistry from that of the homometallic system; this is the interplay between the differing properties of the elements. Furthermore, there is a steady movement towards the view that the main group elements in many such compounds should be better regarded as an integral part of the cluster core, rather than as ligands.4-6 Of the transition metals, among those most well-studied because of their propensity to form metal-metal bonded compounds are the heavier group 8 metals – ruthenium and osmium. The chemistry of these two metals are often similar, differing mainly in their reactivity. The next section will therefore examine the structural types that are known 1 for mixed metal clusters containing ruthenium or osmium and the heavier group 15 elements, viz., As, Sb and Bi. 1.1 Structural feature In contrast to the large number of structures known for Os-P and Ru-P clusters, there are very few examples of clusters containing osmium or ruthenium with the heavier group 15 elements. Many of the clusters containing a heavier group 15 element have them present as a terminal ER3 (E = As, Sb, Bi) ligand. Examples include Os3(CO)10(AsPh3)2,7 Os3(CO)11(SbPh3),8 and Ru3(CO)9(SbPh3)(Ph2PCH2PPh2).9 Clusters in which the E atom is bonded to two or more metal atoms are given in Table 1.1. In comparison with Os-P clusters, those containing a heavier group 15 element tend to adopt an open structure via M-M bond cleavage. This may be due to the larger size of the heavier group 15 elements favoring bridging over a longer M…M distance. As has been observed elsewhere, metal-metal bond lengths involving transition metals vary over a wide range and are very prone to steric and electronic effects of the substituents.10-11 The Ru-Ru bond lengths for the clusters in Table 1.1 span the range 2.731(1) to 3.1700(5) Å, i.e., a spread of 0.44 Å; the corresponding range for the OsOs bond is 2.7524(6) to 3.2332(12) Å, i.e., a spread of 0.48 Å. The bridging hydride is an example of ligand effects on metal-metal bond lengths. The presence of a bridging hydride tends to lengthen the Os-Os bond, while a doubly hydride-bridged Os-Os bond tends to be contracted.10-11 The range from the M-E bond lengths are given in Table 1.2. The ranges reflect the covalent radii of the group 15 elements (1.19 Å, 1.38 Å and 1.46 Å for As, Sb and Bi, respectively.) 2 Table 1.1 Known EM clusters (M = Ru, Os; E = As, Sb, Bi). No. of atoms 3 Metal Skeleton E Clusters M2E: HOs2(CO)6(AsMe2)(C6H4) H2Os3(CO)11(AsR); R = H, Me. Ph Ru2(CO)6(µ-H)(AsMe2){C6H4Cr(CO)3} 4 Ref. 12 13, 14 15 M2E2: Os2(CO)6(AsMe2)(C6H4) 12 E M3E: HOs3(CO)9(AsMe2)(L); L = CHCH, CCH2, C6H4, 16, 17 C6H3Me-4, C6H3iPr, C6H3OMe-3 HOs3(CO)11(AsMe2) 18 Os3(CO)9(µ-H)(AsPh2)(µ3,η2-C6H4) 19 Os3(CO)9(µ-H)(SbMeR)(µ3,η2-C6H4); R = Me, Ph 20 Os3(CO)9(µ-H)(SbMe2)(µ3,η2-C6H3-4-Me) 20 Os3(CO)10(µ-H)(SbMe2)(µ,η2-C6H4) 20 Os3(CO)9(SbMe2)(µ3,η1:η2:η2-C6H3Me2) 20 HOs3(CO)10(SbPh2)L; L = PPh3, AsPh3, SbPh3, CO, t 21,22 BuNC Os3(CO)7(SbPh2){µ,η4- C6H4C(H)CPh}{µ,η2- 23 HC=C(H)Ph} Os3(CO)9(SbPh2)(µ3,η2-CCBut) 23 Os3(CO)9(µ-H)(SbPh2)(µ3,η2-C6H4) 24 Os3(CO)9(µ-H)(SbPh2)(C6H4)(AsPh3) 25 Os3(CO)8(µ-H)(SbPh2)(µ3,η2-C6H4)(AsPh3) 25 Os3(CO)9(µ-H)(SbPh2)(C6H4)(CN tBu) 25 Os3(CO)8(µ-H)(SbPh2)(C6H4)( CN tBu) 25 3 Table 1.1 Continued. No. of atoms 4 Metal Skeleton Clusters Ref. Os3(CO)9(µ-H)(SbPh2)(C6H4)L ; L = PPh3, P(p-tolyl)3, 26 PMe2Ph E Os3(CO)8(µ-H)(SbPh2)(µ3,η2-C6H4)L ; L = PPh3, 26 PMe2Ph 26 Os3(CO)8(SbPh2)(PPh2C6H4)(PPh3)2 26 Os3(CO)7(µ-H)2(SbPh2)(µ3,η2-C6H4)(PPh3)2 26 Os3(CO)8(SbPh2){µ-P(p-tolyl)2(C6H3CH3)}(PPh3)2 9 Ru3(CO)10(SbPh2)(COPh) M2E2: E Ru2(CO)6(AsPh2)2 27 Ru2(CO)6{µ2-As(C6H5)H}2 28 E M3E: E Os3(CO)9(AsC6H4Me)(C6H3Me) 29 Os3(CO)8(AsC6H4Me)(C6H3Me){As(p-tolyl)3} 30 Os3(CO)9(µ3-AsPh)(µ3,η2-C6H4) 19 Os3(CO)8(µ3-AsPh)(µ3,η2-C6H4) (AsPh3) 19 M3E: Os3(CO)10(µ-H)(AsMe2) 18 HOs3(CO)9{AsC10H9(SiMe3)2} 31 H2Os3(CO)9(AsC5H4SiMe3) 31 Os3(CO)9(µ-H)(SbPh2)(AsPh3) 31 Os3(CO)10(µ-H)(SbPh2) 32 Os3(CO)9(µ-H)(SbPh2)(C6H5)L ; L = PPh3, PMe2Ph 26 Ru3(CO)8(µ-H)(AsMe2){C6H4Cr(CO)3} 15 Ru3(CO)6(µ-CO)(AsPh2)(µ-OCC12H7) 33 Ru3(CO)10{µ-cyclo-(AsPh)6} 34 E 4 Table 1.1 Continued. No. of atoms 4 Metal Skeleton Clusters Ref. M3E: E 5 E HOs3(CO)8(AstBu)(NSNAstBu2) 35 H2Os3(CO)9(AsPh2) 36 H3Os3(CO)9(Bi) 37 Ru3(µ2-H)2(CO)9(µ3-AsC6H5) 28 H2Ru3(CO)8(AsPh3)(AsPh) 38 H2Ru3(CO)7(AsPh3)2(AsPh) 38 Ru3H3(CO)9Bi 37 M3E2: Os3(CO)10(SbPh2)(EPh2); E = Sb, P 39 Os3(CO)10(SbPh2){Sb(p-tolyl)2} 39 E E M3E2: Os3(CO)7(AsMe2)2(L); L = C6H4, C6H3iPr 12, 14 E E H2Os3(CO)8(AsMe2)2 18 Os3(CO)7(AsPh2)2(µ3,η2-C6H4) 19 M3E2: Ru3(CO)9Bi2 37 E M4E: H2Os4(CO)12(AsPh) 14 E Ru4(CO)12(µ-H)3{µ-As(CF3)2} 40 E M4E: Ru4(CO)13(µ-H)2(µ4-AsCF3) 41 5 Table 1.1 Continued. No. of Metal atoms Skeleton 5 Clusters Ref. M4E: E 6 Ru4(CO)10(µ-CO)(µ4-AsPh)(µ4,η4-C6H4) 27 Ru4(CO)10(µ-CO){µ4-As(C10H7)}( µ4-C10H6) 42 M4E2: E E Ru4(CO)13(µ3-AsCF3)2 40, 41 Ru4(CO)13(µ3-AsPh)2 34, 43 M4E2: Ru4(CO)14{µ-As(CF3)2}2 40 E E M4E2: Ru4(µ-H)2(CO)12(µ3-AsCF3)2 E 41 M4E2: E Os4(CO)12Bi2 37 M4E2: 37 E E Ru4(CO)12Bi2 E M5E: E Os5(CO)15(µ4-AsPh) 14 Ru5(CO)15(µ4-AsCF3) 40 M5E: E Ru5(CO)13(µ4-AsPh)( µ5,η6-C6H4) 27 M5E: E H2Os5(CO)18(AsH) 13 6 Table 1.1 Continued. No. of atoms 7 Metal Skeleton Clusters Ref. M4E3: E E Ru4(µ-H)2(CO)12(µ3-AsCF3)2(µ-AsCF3) 40 E M5E2: E E Os5(CO)14(µ-H)(SbPh2)(µ4-Sb)(µ3,η2-C6H4)(Ph) 44 M6E: E Os6(CO)20(µ3-SbPh)(µ3,η2-C6H4) 24 Os6(CO)20(µ3-SbMe)(µ3,η2-C6H4) 20 M6E: E H5Os6(CO)18(As) 13 H3Os6(CO)20(As) 13 M6E: E Os6(CO)16(µ-H)(µ4-Sb)(µ3,η2-C6H4)(µ3,η4-C12H8) 24 M6E: E Ru6(CO)18(µ-H)3(µ5-Sb)(SbPh3) 8 36 M4E4: E E Ru4(CO)12(µ3-AsCF3)4 E 40 E M5E3: E Ru5(µ-H)2(CO)15(µ3-AsCF3)3 41 E E E M6E2: Os6(CO)17(µ-H)(µ5-Sb)(µ3,η2-C6H4) 36 7 Table 1.1 Continued. No. of atoms 8 Metal Skeleton E E Clusters Ref. M6E2: Os6(CO)16(µ-H)(µ4-Sb)(SbMe2)(µ3,η2-C6H4)2(CH3) 20 Os6(CO)15(µ-H)2(µ4-Sb)(SbPh2)(µ3,η2-C6H4)(µ3,η4- 24 C12H8) 24 Os6(CO)16(µ-H)(µ4-Sb)(SbPh2)(µ3,η2-C6H4)2(C6H5) 24 Os6(CO)15(µ-H)(µ4-Sb)(SbPh2) (µ3,η2-C6H4)(µ3,η6C6H4) (C6H5) 24 Os6(CO)14(µ-H)2(µ4-Sb)(SbPh2)(SbPh3)(µ3,η2-C6H4) (µ3,η4-C12H8) E E M6E2: Os6(CO)14(µ-H)(µ4-Sb)(SbPh2)(µ3,η4-C12H8)(C6H5) 45 (CNtBu)4 Os6(CO)15(µ-H)(µ4-Sb)(SbPh2)(µ3,η4-C12H8)(C6H5) 45 (CNtBu)3 E M6E2: {Os3(CO)10(µ-H)(SbPh2)}2 39 [Ru3(CO)10(µ-H){µ- As(CF3)2}]2 40 E Table 1.2 Ranges of the M-E bond lengths. Ru-E Bond lengths (Å) Os-E Bond lengths (Å) Ru-As 2.366(1)-2.8568(4) Os-As 2.406(1)-2.5730(7) Ru-Sb 2.5973(4)-2.7905(5) Os-Sb 2.5376(11)-2.8916(6) Ru-Bi 2.756(1)-2.839(1) Os-Bi 2.799(2)-2.923(1) 8 1.2 Reactivity Earlier work from our group has shown that osmium-antimony clusters often show novel reactivity patterns which are different from the phosphorus or arsenic analogues. One of the more well-studied cluster among these is Os3(CO)10(µ-H)(µ-SbPh2), 1, which can be obtained in reasonable yield from the salt elimination reaction of [Os3(µ-H)(CO)10(µ-CO)]- and an excess of Ph2SbCl in THF (Scheme 1.1). Two other products, Os3(CO)10(µ-SbPh2)2, A, with an SbPh2 bridging a closed Os-Os edge, and [Os3(CO)10(µ-H)(µ-SbPh2)]2, B, a dimeric version of cluster 1 which comprises two Os3(CO)10(µ-H)(µ-SbPh2) moieties linked via two SbPh2 bridges, are also obtained. Cluster A can also be obtained from the reaction of 1 and Ph2SbCl, and the Os-Os bond bridged by the SbPh2 moiety is fluxional.39 Cluster 1 undergoes nucleophilic addition reactions with two-electron donors L (where L = EPh3, CO or tBuNC) via an Os-Os bond cleavage. Depending on the identity of L, up to three isomers have been observed (Scheme 1.2).21-22 It has been established that tertiary phosphines and arsines tend to occupy equatorial positions while N and C donor ligands which are rod-like, such as nitriles and isonitriles, tend to occupy axial positions; this has been attributed to stereoelectronic reasons;2 The axial position is electronically favored as it places poorer π-acid ligands trans to a CO, as opposed to mutually trans COs if the ligand is in an equatorial position. For phosphines and related sterically bulky ligands, the greater steric hindrance of the axial position disfavors it. In the reaction of cluster 1 with tBuNC, however, three isomers were observed, in which the isonitrile ligand occupied equatorial and axial positions.22 These adducts can undergo decarbonylation, especially at elevated temperatures. For example, the reaction of cluster 1 with AsPh3 at 65°C gave 9 10 Os 1 Os Os H SbPh2 Ph2SbCl + Sb Ph2 A Os Os SbPh2 THF Os H RT - + Scheme 1.1 Preparation of cluster 1. Os Os Os CO + Os Ph2SbCl Os Os H B Sb Ph2 H Ph2 Sb Os Os Os Os3(CO)9(µ-H)(µ-SbPh2)(AsPh3), F, in which all the three Os-Os bonds remained intact and the AsPh3 occupied an equatorial position on the unique unbridged osmium.21 SbPh2 Os H Os + L Os L = EPh3, CO, tBuNC; 1 E = Sb, As, P H H H Os Os Os Os SbPh2 + Os SbPh2 + Os SbPh2 Os Os L C L D Os L E Scheme 1.2 Reaction of 1 with nucleophiles. 11 In contrast to the above, the reactivity of 1 with the chalcogens are unexplored. The contribution of transition metal-carbonyl compounds and the chalcogens introduces novel structural and reactivity features. For example, it has been found that Os3(CO)12-n(NCCH3)n (n = 1 or 2) reacted with R2E2 (R = Ph or Me; E = S, Se or Te) to afford clusters Os3(CO)10(µ-ER)2, G, in two isomeric forms G1 and G2. 46-48 In line with our general interest in transition metal-main group element mixed-metal clusters, we embarked on an exploration of the chemistry of 1 with some compounds of the group 16 elements. Os Os ER G1 Os ER Os Os Os H3CCN R2E2 or/ and or NCCH3 R = Ph or Me E = S, Se or Te Os Os ER G2 Os Os Os H3CCN E R Os Scheme 1.3 Reaction of triosmium clusters and R2E2 (R = Ph or Me; E = S, Se or Te). 12 1.3 References 1 Mingos, D. M. P.; Wales, D. J. Introduction to Cluster Chemistry, 1990. 2 Deeming, A. J. In Comprehensive Organometallic Chemistry II; Abel, E. W.; Stone, F. G. A.; Wilkinson, G.; Eds.; Elsevier: Oxford, 1995; Vol. 7, Chap. 12, pp. 683746. 3 Crabtree, R. H. The Organometallic Chemistry of the Transition Metals; Wiley, 2005, 379. 4 See, for example, Fehlner, T. P. Inorganomettalic Chemistry; Plenum: New York, 1992; Hermann, W. A. Angew. Chem., Int. Ed. Engl. 1986, 25, 56; Nicholls, J. N. Polyhedron 1984, 3, 1307. 5 Whitmire, K. H. Adv. Organomet. Chem. 1998, 42, 1. 6 Leong, W. K. Bull. Sing. N. I. C. 1996, 24, 51. 7 Bradford, C. W.; Nyholm, R. S. J. Chem. Soc., Dalton Trans. 1973, 529. 8 J. N. Nicholls, M. D. Vargas, Inorg. Synth. 1989, 28, 232. 9 Shawkataly, O.; Ramalingam, K.; Fun, H. K.; Abdul Rahman, A.; Razak, I. A. J. Cluster Sci. 2004, 15, 387. 10 Pomeroy, R. K. In Comprehensive Organometallic Chemistry II; Abel, E. W.; Stone, F. G. A.; Wilkinson, G.; Eds.; Elsevier: Oxford, 1995; Vol. 7, Chap. 15, pp. 835906. 11 Broadhurst, P. V.; Johnson, B. F. G.; Lewis, J. J. Chem. Soc., Dalton Trans. 1982, 1881. 12 Deeming, A. J.; Kimber, R. E.; Underhill, M. J. Chem. Soc., Dalton Trans. 1973, 2589. 13 Guldner, K.; Johnson, B. F. G.; Lewis, J.; Massey, A. D.; Bott, S. J. Organomet. Chem. 1991, 408, C13. 14 Guldner, K.; Johnson, B. F. G.; Lewis, J. J. Organomet. Chem. 1988, 355, 419. 15 Cullen, W. R.; Rettig, S. J.; Zhang, H. Organometallic 1993, 12, 1964. 16 Arce, A. J.; Deeming, A. J. J. Chem. Soc., Dalton Trans. 1982, 1155. 17 Cooksey, C. J.; Deeming, A. J.; Rothwell, I. P. J. Chem. Soc., Dalton Trans. 1981, 1718. 18 Guldner, K.; Johnson, B. F. G.; Lewis, J.; Owen, S. M.; Raithby, P. R. J. Organomet. Chem. 1988, 341, C45. 13 19 Tay, C. T.; Leong, W. K. J. Organomet. Chem., 2001, 625, 231. 20 Chan, K. H; Leong, W. K.; Mak, K. H. Garvin Organometallic, 2006, 25, 250. 21 Chen, G.; Leong, W. K. J. Chem. Soc., Dalton Trans. 1998, 2489. 22 Chen, G.; Leong, W. K. J. Organomet. Chem. 1999, 574, 276. 23 Deng, M.; Leong, W. K. Organometallics 2002, 21, 1221. 24 Chen, G.; Leong, W. K. Organometallic 2001, 20, 2280. 25 Chen, G.; Deng, M.; Lee, C. K.; Leong, W. K.; Tan, J.; Tay, C. T. J. Organomet. Chem. 2006, 691, 387. 26 Chen, G.; Deng, M.; Lee, C. K.; Leong, W. K. Organomeallic 2002, 21, 1227. 27 Knox, S. A. R.; Lloyd, B. R.; Morton, D. A. V.; Nicholls, S. M.; Orpen, A. G.; Vinas, J. M.; Weber, M.; Williams, G. K. J. Organomet. Chem. 1990, 394, 385. 28 Ang, H. G.; Ang, S. G.; Du, S. W. J. Organomet. Chem. 1999, 590, 1. 29 Johnson, B. F. G.; Lewis, J.; Massey, A. D.; Braga, D.; Grepioni, F. J. Organomet. Chem. 1989, 369, C43. 30 Jackson, P. A.; Johnson, B. F. G.; Lewis, J.; Massey, A. D.; Braga, D.; Gradella, C.; Grepioni, F. J. Organomet. Chem. 1990, 391, 225. 31 Arce, A. J.; Deeming, A. J.; DeSanctis, Y.; Garcia, A. M.; Manzur, J.; Spodine, E. Organometallic 1994, 13, 3381. 32 Johnson, B. F. G.; Lewis, J.; Whitton, A. J.; Bott, S. J. Organomet. Chem. 1990, 389, 129. 33 Shawkataly, O.; Puvanesvary, K.; Fun, H. K.; Sivakumar, K. J. Organomet. Chem. 1998, 565, 267. 34 De Silva, R. M.; Mays, M. J.; Solan, G. A. J. Organomet. Chem. 2002, 664, 27. 35 Süss-Fink, G.; Guldner, K.; Herberhold, M.; Gieren' A.; Huebner, T. J. Organomet. Chem. 1985, 279, 447. 36 Chen, G.; Leong, W. K. J. Cluster Sci. 2006, 17, 111. 37 Ang, H. G.; Hay, C. M.; Johnson, B. F. G.; Lewis, J.; Raithby, P. R.; Whitton, A. J. J. Organomet. Chem. 1987, 330, C5. 38 Gremaud, G.; Jungbluth, H.; Stoeckli-Evans, H.; Süss-Fink, G. J. Organomet. Chem. 1990, 388, 351. 14 39 Chen, G.; Leong, W. K. J. Chem. Soc., Dalton Trans. 2000, 4442. 40 Lee, Y. W.; Ph.D. thesis, National University of Singapore, 1995. 41 Ang, H. G.; Ang, S. G.; Du, S.; Sow, B. H.; Wu, X. J. Chem. Soc., Dalton Trans. 1999, 2799. 42 Cullen, W. R.;. Rettig, S. J;. Zheng, T. C Organometallic 1995, 14, 1466. 43 Field, J. S.; Haines, R. J.; Smit, D. N. J. Organomet. Chem. 1982, 240, C23. 44 Deng, M.; Leong, W. K. J. Chem. Soc., Dalton Trans. 2002, 1020. 45 Chen, G.; Leong, W. K. Organometallic 2001, 20, 5771. 46 Johnson, B. F. G. In Transition Metal Clusters; Johnson, B. F. G.; Ed.; Wiley: Chichester, 1980; Chap. 1. 47 Arce, A. J.; Arrojo, P.; De Sanctis, Y. Polyhedron 1992, 11, 1013. 48 Zhang, J.; Leong, W. K. J. Chem. Soc., Dalton Trans. 2000, 1249. 15 Chapter 2 Reaction of Os3(CO)10(µ-H)(µ-SbPh2), 1 with group 16 compounds As mentioned in the previous chapter, antimony-containing osmium clusters are known to undergo nucleophilic addition.1-2 While triosmium clusters are known to react with group 16 elements, in contrast, the reactivity of antimony-containing osmium clusters with group 16 elements has not been explored. In this section, the synthesis and reactivity of the cluster Os3(CO)10(µ-H)(µ-SbPh2), 1 with some group 16 compounds are reported. 2.1 Reaction of Os3(CO)10(µ-H)(µ-SbPh2) with REER and PhEH The cluster Os3(CO)10(µ-H)(µ-SbPh2), 1 reacted with an equimolar of REER or PhEH (R = Ph, Me; E = S, Se, Te) in hexane at room temperature to afford a yellow solid (5); TLC separation of the supernatant gave several bands in low yields, of which the two major ones (3 and 4) have been characterised (Scheme 2.1). SbPh2 Os + H Os REER or REH Os R = Ph, Me E = S, Se, Te Hex ER Os H Os Os + Os Os RE 3 3a: R = Ph, E = S 3b: R = Ph, E = Se 3c: R = Ph, E = Te 3d: R = Me, E = Se RT SbPh2 + Unknown Os 4 4a: R = Ph, E = S 4b: R = Ph, E = Se 5 5a: R = Ph, E = S 5b: R = Ph, E = Se 5c: R = Ph, E = Te 5d: R = Me, E = Se Scheme 2.1 Reaction of Os3(CO)10(µ-H)(µ-SbPh2) with REER and REH. 16 The identities of Os3(CO)10(µ-H)(µ-SPh) (3a), Os3(CO)10(µ-H)(µ-SePh) (3b), Os3(CO)10(µ-H)(µ-TePh) (3c) and Os3(CO)10(µ-H)(µ-SeMe) (3d) were made on the basis of their IR spectra in the carbonyl region and bridging hydride resonance in their 1 H NMR spectra, which matched those reported earlier;3-5 the IR spectrum for 3a 2200 2150 2100 2050 Wavenumber cm-1 2000 1990.65 1985.91 2002.71 2025.16 2019.57 2060.02 2068.70 2109.54 50 60 Transmittance [%] 70 80 90 100 (Figure 2.1) is typical. 1950 Figure 2.1 Infrared spectrum (in hexane) of Os3(CO)10(µ-H)(µ-SPh), 3a. C:\Documents and Settings\NTU\My Documents\wenling\HOs3(CO)10(SPh) in Hex (bottom).0 HOs3(CO)10(SPh) in Hex (bottom) 1900 Hex 18/03/2010 Page 1/1 17 The profiles of the CO stretching vibrations of 4a and 4b were similar, indicating that they were analogous products (Figure 2.2). The pattern was also different from that for the two known clusters Os3(CO)10(µ-SbPh2)(µ-EPh2) (E = P or Sb, 4e and 4f, respectively), in particular, an extra peak at 2031 cm-1 or 2029 cm-1 was observed for 2200 2150 2100 2050 Wavenumber cm-1 1960.10 1972.08 1993.43 2008.17 2036.66 2031.34 2024.90 2061.91 2101.37 92 Transmittance [%] 94 96 98 100 4a and 4b, respectively. 2000 1950 1900 C:\Documents and Settings\NTU\My Documents\wenling\SbEPh & Os2\SbSPh in Hex.0 4b SbSPh in Hex Hex 16/09/2009 2101mw, 2060vs, 2037s, 2029s, 2024s, 2008w, 1992mw, 1970mw, 1959w 4e Page1992mw, 1/1 2104w, 2062mw, 2027s, 2000mw, 1967w, 1955m 4f 2102mw, 2054mw, 2033sh, 2026s, 2001w, 1983mw, 1972w, 1960mw Figure 2.2 Infrared spectrum (in hexane) of Os3(CO)10(µ-SbPh2)(µ-SPh), 4a, and tabulated values for 4b, 4e and 4f.6 18 The identities 4a and 4b were established by single crystal X-ray diffraction studies as the clusters Os3(CO)10(µ-SbPh2)(µ-SPh) and Os3(CO)10(µ-SbPh2)(µ-SePh), respectively. The ORTEP diagram of 4a is shown in Figure 2.3, and selected bond parameters for 4a, 4b, 4e and 4f are given in Table 2.1. The structures of both 4a and 4b show a SbPh2 moiety bridging an open Os-Os edge and an SPh or SePh moiety bridging a closed Os-Os edge. This indicated that 4a and 4b have undergone a novel nucleophilic addition in which a metal-metal bond has been cleaved. In contrast to 4e and 4f, the Os2E (E = S or Se) plane in 4a and 4b is roughly perpendicular to the Os3Sb plane; the dihedral angles between the Os3Sb and Os2E planes are 93.1(1)° and 92.3(1)° for 4a and 4b, respectively. In contrast, the EPh2 ligand bridging the closed Os-Os edge in 4e and 4f is roughly coplanar with the Os3Sb quadrilateral, with the dihedral angle being 1.6° and 1.2°, respectively. This difference in structure is presumably due to the additional Ph group for E = P or Sb; bending of the EPh 2 group out of the Os3Sb plane would not meet with steric hindrance from the axial carbonyl on the unbridged osmium (eg., CO(34) in figure 2.3).6 As may be expected, the Os-E bond length increases, and the Os-E-Os bond angle decreases, with increasing size of the atom E (covalent radii: S = 1.05 Å; P = 1.07 Å; Se = 1.20 Å; Sb = 1.39 Å). That the EPh group in 4a and 4b is approximately perpendicular to the Os3Sb plane compared to the almost coplanarity for the EPh2 group in the P and Sb analogues, has significant effects on bond parameters. Thus the Os(1)-E(5) and Os(2)-E(5) lengths are significantly different in the latter pair of clusters but not so for 4a and 4b. This may be attributed to the fact that as the EPh2 fragment is coplanar with the Os3Sb ring, E(5) is trans to Sb(4) along the E(5)-Os(1) 19 direction, but to Os(3) along the E(5)-Os(2) direction. This may imply that the trans influence of Os is weaker than Sb. Figure 2.3 ORTEP diagram for 4a. 20 Table 2.1 Selected bond lengths (Å) and angles (°) for 4a, 4b, 4e and 4f. 6 Ph Ph E(5) Os(1) E(5) Sb(4) Os(1) Sb(4) Ph Os(2) Bond parameters Os(3) Os(2) Os(3) 4e 4f 4a 4b P Sb S Se Os(1)-Os(2) 2.9436(5) 3.0408(6) 2.8622(2) 2.8680(6) Os(2)-Os(3) 2.9968(5) 2.9967 (6) 3.0062(2) 2.9933(6) Os(1)-Sb(4) 2.6334(6) 2.6384(8) 2.6585(3) 2.6488(8) Os(3)-Sb(4) 2.6993(6) 2.7132(8) 2.6782(3) 2.6650(8) Os(1)-E(5) 2.350(2) 2.6164(9) 2.4057(10) 2.5175(10) Os(2)-E(5) 2.311(2) 2.6023(9) 2.4042(10) 2.5178(11) Os(1)-Sb(4)-Os(3) 109.07(2) 110.61(3) 106.871(10) 106.77(3) Os(1)-Os(2)-Os(3) 93.965(14) 93.574(17) 93.812(6) 93.359(16) Os(2)-E(5)-Os(1) 78.33(7) 71.28(2) 73.03(3) 69.44(3) 1.6 1.2 93.1 92.3 1.05 1.07 1.20 1.39 E Dihedral angle between Os3Sb and Os2E Covalent Radius of E 21 A plausible mechanism for the formation of 4a and 4b that is in accordance with that for the phosphorus and antimony analogues,6, 7 is shown in Scheme 2.2. Evidence for the intermediate H is provided by the presence of a resonance at δ -8.70 when the reaction with PhSeSePh was monitored by 1H NMR spectroscopy. After formation of H, an isomer of 4 in which the ER group bridged the open Os-Os bond is formed. The isostructural analogue of 4 then undergo a rearrangement due to the higher tendency for an SbPh2 to span an open Os…Os edge compared to an ER group, via a metalmetal bond rearrangement. Such a rearrangement has been reported earlier.6 H SbPh2 Os + H Os Os REER or REH Os SbPh2 Os Os E ER or H R H Os SbPh2 Os RE Os Os rearrangement SbPh2 Os RE Os 4 Scheme 2.2 Proposed reaction scheme for the formation of 4a and 4b. 22 Compounds 5 are the major product from the reaction of Os3(CO)10(µ-H)(µ-SbPh2), 1 with REER or REH. The presence of CO absorption in the region from 2200 to 1800 cm-1 in their IR spectra showed that they are osmium-containing clusters (Table 2.2). The IR spectrum of 1 with REER or REH shows similar CO absorption patterns (2087w, 2022s and 1958sh for 5c is typical) suggested that they have similar structures (Figure 2.4). The amount of 5 formed increased with reaction time until the starting material is consumed. Stirring separate hexane solutions of 3b or 4b at room temperature showed changes in their IR spectra but there was no conversion to 5b. Compound 5b is thermally stable; it remained unreacted after heating at 115 °C for 36 h. Thus we believe that compounds 3, 4 and 5 were formed via different pathways. Table 2.2 IR and 1H NMR spectra of compounds 5. Compounds ν(CO) (CH2Cl2, cm-1) 1 H NMR (CDCl3) 5a 2111w, 2022mw, 2015s, 1967m δ 8.50-6.00 (br, Ph) 5b 2110w, 2091w, 2074w, 2026s, 1963m δ 8.50-6.00 (br, Ph) 5c 2087w, 2022s, 1958m δ 8.00-6.50 (br, Ph) 5d 2089w, 2055mw, 2007s δ 8.00-7.00 (br, Ph), 3.00-1.90 (br, Me) δ 7.95-6.55 (br, 16H, Ph), 5e 2087w, 2025s, 1962m 4.00-3.50 (br, 6H, OMe), 2.52-2.11 (br, 6H, Me) 23 100 98 Transmittance [%] 92 94 96 Ph2Te2 2200 2150 2100 2050 1958.15 2021.50 2086.72 88 90 PhTeH 2000 1950 1900 1850 1800 Wavenumber cm-1 C:\Documents and Settings\NTU\My Documents\wenling\Solid, recrystalline\WL113p, Ph2Te2, DCM.0 WL113p, Ph2Te2, DCM C:\Documents and Settings\NTU\My Documents\wenling\Solid, recrystalline\WL123p, PhTeH, DCM.0 WL123p, PhTeH, DCM Figure 2.4 IR spectra (in CH2Cl2) of compound 5c. DCM DCM 09/11/2009 09/11/2009 Page 1/1 The 1H NMR spectra of 5 showed a broad peak in the aromatic region; that for 5c is shown in Figure 2.5. Likely causes for such peak broadening include paramagnetism, fluxionality or a fast equilibrium. The magnetic susceptibility of 5, as determined with a magnetic susceptibility balance, was zero (for 5a, 5b and 5c), and T1 for the aromatic protons, as estimated by the inversion recovery method was long (2.5s for 5c), showing that 5 were not paramagnetic. 24 Figure 2.5 1H NMR (500 MHz, CDCl3) of compounds 5c. In order to establish if 5 was fluxional, and to obtain some information on its composition, the compound 5e was prepared from the reaction of Os3(CO)10(µ-H)[µSb(p-OCH3C6H4)2] with (p-tolyl)2Te2. The 1H NMR spectrum of 5e showed a broad aromatic resonance at 7.95-6.55 ppm, OMe at 3.81 ppm and Me at 2.36 ppm, in the integration ratio of 2.7, 1.0 and 1.0, respectively (Figure 2.6). This suggested that 5e consisted of one Sb(p-OCH3C6H4)2 group and one (p-tolyl)2Te2 group. A variable temperature 1H NMR spectroscopic study showed no change in the spectrum with temperature except for a decrease in intensity on lowering the temperature, which may be accounted for by precipitating out of the sample (Figure 2.7). 25 Figure 2.6 1H NMR (500 MHz, CDCl3) spectrum of compound 5e. Figure 2.7 Variable temperature 1H NMR (400 MHz, d8-toluene) of 5e (Top: 80°C; middle: 22°C; bottom: -80°C). 26 Attempts were also made on the characterisation of the compounds 5 by studying their reactivity. Thus 5b remained largely unreacted after heating with PPh3 in toluene at 60 °C over 2 d. TLC separation of the reaction mixture did yield two yellow crystalline solids, 6 and 7. The spectroscopic data for 6 and 7 suggested that they contain phosphorus, but they remain otherwise unidentified. A reaction of 5c with excess bromine in dichloromethane afforded three products after recrystallization. The products remain unidentified at this stage. 2.2 Conclusion The reaction of Os3(CO)10(µ-H)(µ-SbPh2) with REER or PhEH (R = Ph, Me; E = S, Se, Te) gave the known compounds Os3(CO)10(µ-H)(µ-SER), 3a-d, the new compounds Os3(CO)10(µ-SbPh2)(µ-EPh), 4a-b, and the as-yet unidentified compounds, 5a-d. Compounds 3, 4 and 5 were formed via different pathways. The new compounds 4 appear to have resulted from nucleophilic addition of an EPh group, with cleavage of an Os-Os bond. Unlike the structurally related clusters Os3(CO)10(µSbPh2)(µ-EPh2) where E = P or Sb, the EPh group in 4 is roughly perpendicular to the Os3Sb plane. 27 2.3 References 1 Chen, G.; Leong, W. K. J. Chem. Soc., Dalton Trans. 1998, 2489. 2 Chen, G.; Leong, W. K. J. Organomet. Chem. 1999, 574, 276-278. 3 G. R. Crooks, B. F. G. Johnson, J. Lewis, and I. G. Williams, J. Chem. Soc. A, 1969, 797. 4 Adams, R. D.; Horvath, I. T. Inorg. Chem. 1984, 23, 4718. 5 Zhang, J.; Leong, W. K. J. Chem. Soc., Dalton Trans. 2000, 1249. 6 Chen, G.; Leong, W. K. J. Chem. Soc., Dalton Trans. 2000, 4442. 7 Chen, G.; Leong, W. K. J. Chem. Soc., Dalton Trans. 1998, 15, 2489. 28 Chapter 3 Experimental 3.1 General experimental All manipulations were carried out using standard Schlenk techniques under an inert atmosphere of argon. Solvents that were used for reactions were distilled over the appropriate drying agents under argon before use. The products were generally separated on 20 X 20 cm TLC plates coated with silica gel 60F254. 1H and 31 P{1H} NMR spectra were recorded on a Bruker AC 300 or AMX 500 FT-NMR spectrometer, with chemical shifts referenced to residual solvent peaks in CDCl3, unless otherwise stated. Infrared spectra were recorded on a Bruker Alpha FT-IR spectrometer at a resolution of 2 cm-1, as solutions in hexane (unless otherwise stated) in a solution cell with NaCl windows. ESI-MS and Q-Tof spectra were recorded on MATLCQ and MassLynx V4.1 spectrometers, respectively. Elemental analyses were performed by the microanalytical laboratory at NUS. Crystal data were collected on a Bruker-AXS Smart Apex CCD single-crystal diffractometer in NUS or a Bruker-AXS Smart ApexII CCD single-crystal diffractometer in NTU. Single crystal X-ray crystallographic studies were carried out by A/P Leong Weng Kee and Dr Li Yongxin. The compounds Os3(CO)10(µ-H)(µ-SbPh2), 1,1-2 (p-OCH3C6H4)2SbCl,3 (p-tolyl)2Te2,4 and PhTeH,5 were prepared according to reported procedures. All other reactants and reagents were purchased from commercial sources and used as supplied without further purification. 29 3.2 Reaction of [PPN][HOs3(CO)11] with (p-OCH3C6H4)2SbCl To a Schlenk tube containing [PPN][HOs3(CO)11] (200 mg, 0.14 mmol) and THF (35 ml) was added (p-OCH3C6H4)2SbCl (156 mg, 0.42 mmol). The color of the solution changed from dark red to yellow immediately. The mixture was allowed to stir for 5 min at room temperature. TLC separation using dichloromethane/hexane (1:4, v/v) as eluant gave two bands. Band 1 (Rf = 0.31) gave a yellow solid of Os3(CO)10(µ-H)[µ-Sb(p-OCH3C6H4)2], 2. Yield = 11 mg, 7%. IR (cm-1): νCO 2101m, 2052vs, 2020s, 2011ms, 1996mw, 1988m, 1978w 1 H NMR (CDCl3):  7.79-6.85 (m, 10H, Ph), -19.81 (s, 1H, OsHOs) TOF-MS: 1189 [M+H]+ Band 2 (baseline) gave yellow solid. Yield = 109 mg. This band was not characterized. 3.3 Reaction of 1or 2 with REER or REH (R = Ph, Me; E = S, Se, Te) In a typical experiment, to a Schlenk tube containing 1 (60 mg, 50 µmol) and hexane (20 ml) was added an equimolar amount of PhEEPh. The reaction mixture was stirred at room temperature until the IR spectrum of the solution showed that 1 has been consumed. A yellow solution with a yellow precipitate was obtained. The yellow precipitate (5) was collected by filtration through a sinter and the supernatant was chromatographed on silica gel plates using dichloromethane/hexane (1:2, v/v) as eluant to afford two bands - Os3(CO)10(µ-H)(µ-ER) (3) and Os3(CO)10(µ-SbPh2)(µEPh) (4). The amount of reactants, reaction time, and the reaction products, are summarised in Table 3.1; spectroscopic data of the reaction products are summarised in Table 3.2. 30 31 ~3.5 ~1.5 ~4 ~4 Ph2Te2 (22, 50) Me2S2 (4, 40) Me2Se2 (8, 40) (p-tolyl)2Te2 (4, 8) PhSH (5, 40) PhSeH (5, 40) PhTeH (from Ph2Te2; 10, 20) 1 (60, 50) 1 (50, 40) 1 (50, 40) 2 (10, 8) 1 (50, 40) 1 (50, 40) 1 (50, 40) ~2 ~12 ~9 ~2.5 Ph2Se2 (17, 50) 1 (60, 50) ~2 (d) Ph2S2 (12, 50) (mg, µmol) (mg, µmol) Reaction Time 1 (60, 50) R2E2/ REH Cluster Products 3c (Rf = 0.68, 1 mg, 2 %); 5c (55 mg) 3b (Rf = 0.61, 2 mg, 4 %); 4b (Rf = 0.45, 2 mg, 4 %); 5b (37 mg) 3a (Rf = 0.58, 1 mg, 1 %); 4a (Rf = 0.38, 1 mg, 2 %); 5a (54 mg) 5e (8 mg) 3d (Rf = 0.82, 2 mg, 4 %); 5d (30 mg) No reaction 3c (Rf = 0.68, 2 mg, 4 %); 5c (70 mg) 3b (Rf = 0.61, 2 mg, 4 %); 4b (Rf = 0.45, 1 mg, 1 %); 5b (62 mg) 3a (Rf = 0.58, 2 mg, 4 %); 4a (Rf = 0.38, 1 mg, 2 %); 5a (54 mg) Table 3.1 Amount of reactants, reaction time and the reaction products. 32 7.61-7.05 (m, 5H, Ph), -18.84s (s, 1H, OsHOs) 7.82-7.05 (m, 5H, Ph), -17.85s (s, 1H, OsHOs) 7.60-7.05 (m, Ph) 8.50-6.00 (br, Ph) 8.00-6.50 (br, Ph) 8.00-6.50 (br, Ph) 8.00-7.00 (br, Ph), 3.00-1.90 (br, Me) 7.95-6.55 (br, 16H, Ph), 4.00-3.50 (br, 6H, OMe), 2.52-2.11 (br, 6H, Me) 2105w, 2065vs, 2055sh, 2025s, 2009s, 1999mw, 1986w 2108w, 2066vs, 2057sh, 2024vs, 2015s, 1999m, 1988mw 2101mw, 2062vs, 2037s, 2031s, 2025s, 2008w, 1993mw, 1972mw, 1960w 2101mw, 2060vs, 2037s, 2029s, 2024s, 2008w, 1992mw, 1970mw, 1959w 2111w, 2022mw, 2015s, 1967m 2110w, 2091w, 2074w, 2026s, 1963m 2087w, 2022s, 1958m 2089w, 2055mw, 2007s 2087w, 2025s, 1962m 3c (R = Ph, E = Te) 3d (R = Me, E = Se) 4a (E = S)b 4b (E = Se)c 5a 5b 5c 5d 5e b Infrared spectrum of 5 is recorded in CH2Cl2 TOF-MS: 1238 [M+H]+ c TOF-MS: 1283 [M]+ a 7.61-7.13 (m, 5H, Ph), -17.64 (s, 1H, OsHOs) 2108w, 2067vs, 2058sh, 2024vs, 2015m, 2002mw, 1989w 3b (R = Ph, E = Se) 7.70-7.05 (m, Ph) 7.51-7.21 (m, 5H, Ph), -17.04 (s, 1H, OsHOs) 2109w, 2069vs, 2060sh, 2025vs, 2020sh, 2003mw, 1991w, 1986w H NMR (δ) 3a (R = Ph, E = S) 1 ν(CO)a (cm-1) Products Table 3.2 Spectroscopic data of the reaction products. 3.4 Reaction of clusters 5 3.4.1 Thermolysis of 5b Compound 5b (13 mg) was placed in a Carius tube with toluene (5 mL) and the reaction mixture degassed by three freeze-pump-thaw cycles. The suspension was then heated at 115 °C for 36 h upon which the color of the solution changed from yellow to brown. TLC separation of the mixture using dichloromethane/hexane (1:1, v/v) as eluant gave three bands. Bands 1 and 2 were obtained in low yield. Baseline gave unreacted 5b (3 mg) as identified spectroscopically. 3.4.2 Reaction of 5b with PPh3 PPh3 (6 mg, 23 µmol) was added to a toluene solution (5 ml) of cluster 5b (30 mg). The reaction mixture was stirred at 60 °C for 2 d. The solvent was removed in vacuo and redissolved in dichloromethane to give a yellow solution. Recrystallization of the yellow residue from dichloromethane/ hexane gave unreacted (5b); TLC separation of the supernatant using dichloromethane/hexane (1:1, v/v) as eluant gave two bands. Band 1 (Rf = 0.69) afford yellow crystalline of 6. Yield = 6 mg. IR (cm-1): νCO 2094w, 2060vs, 2017m, 2010m, 1997s, 1987s, 1971ms, 1941m 1 H NMR (C6D6):  7.75-6.89 (m, Ph), -12.07 (d, JPH = 5.50 Hz) P{1H} NMR (C6D6):  19.56 (s), 5.20 (s) 31 Band 2 (Rf = 0.55) afforded yellow crystalline 7. Yield = 3 mg. IR (cm-1): νCO 2013s, 1950s 1 H NMR (C6D6):  7.59-6.87 (m, Ph) P{1H} NMR (C6D6):  -15.14 (s) 31 33 3.4.3 Reaction of 5c with bromine Bromine (0.05 mL) was added dropwise to a dichloromethane solution (5 ml) of cluster 5c (40 mg). The reaction mixture was stirred at room temperature for 5 h. A dark yellow solution with a yellowish green precipitate was obtained. The yellowish green precipitate (8) was collected by filtration through a sinter. After removal of solvent, the filtrate was recrystalized from dichloromethane/ hexane to give a yellow solid (9). Removal of solvent from the supernatant afforded a yellow residue (10). 8: Yield = 14 mg. IR (KBr, cm-1): νCO 2128w, 2042s, 1971m 1 H NMR (d6-DMSO):  8.50-6.90 (br, Ph) 9: Yield = 24 mg. IR (CH2Cl2, cm-1): νCO 2121m, 2097w, 2068vs, 2061vs, 2036sh, 1995w 1 H NMR (C6D6):  8.21-6.76 (m, Ph) 10: Yield = 5 mg. IR (cm-1): νCO 2176w, 2120sh, 2112vs, 2089s, 2078vs, 2067sh, 2050vs, 2041m, 2033m, 1993w, 1980w 1 H NMR (C6D6):  8.18-6.80 (m, Ph) 34 3.5 Crystallographic studies Crystals of diffraction quality were grown by slow evaporation of a dichloromethane/ hexane mixture. X-ray crystallographic data were collected on a Bruker APEX diffractometer equipped with a CCD detector, employing Mo K radiation ( = 0.71073 Å), at 298 K (in NUS) and 173 K (in NTU) with the SMART suite of programs.6 Data were processed and corrected for Lorentz and polarisation effects with SAINT,7 and for absorption effects with SADABS.8 Structural solution and refinement were carried out with the SHELXTL suite of programs.9 Crystal and refinement data of 4a and 4b are summarised in Table 3.3. 35 Table 3.3 Crystallographic table for clusters 4a and 4b. Clusters 4a 4b C28H15O10Os3SSb 1235.81 Yellow, block 0.24 x 0.20 x 0.14 Triclinic Pī 8.4366(3) C28H15O10Os3 1282.71 Yellow, block 0.42 x 0.33 x 0.29 Triclinic Pī 8.2782(4) b, Å c, Å , deg deg 12.0998(4) 16.4773(6) 81.4320(10) 77.0250(10) 12.0971(6) 16.2558(8) 80.978(3) 77.261(2) deg Volume, Å3 Z Density, Mgm-3 Abs. coefficient, mm-1 72.0680(10) 1553.66(9) 2 2.642 13.209 73.478(3) 1514.53(13) 2 2.813 14.683 F(000)  range for data collection Index ranges 1116 2.09 to 30.47 1152 2.08 to 26.37 -11[...]... clusters are known to react with group 16 elements, in contrast, the reactivity of antimony- containing osmium clusters with group 16 elements has not been explored In this section, the synthesis and reactivity of the cluster Os3(CO)10(µ-H)(µ -SbPh2), 1 with some group 16 compounds are reported 2.1 Reaction of Os3(CO)10(µ-H)(µ -SbPh2) with REER and PhEH The cluster Os3(CO)10(µ-H)(µ -SbPh2), 1 reacted with. .. regarded as an integral part of the cluster core, rather than as ligands.4-6 Of the transition metals, among those most well-studied because of their propensity to form metal-metal bonded compounds are the heavier group 8 metals – ruthenium and osmium The chemistry of these two metals are often similar, differing mainly in their reactivity The next section will therefore examine the structural types that... for mixed metal clusters containing ruthenium or osmium and the heavier group 15 elements, viz., As, Sb and Bi 1.1 Structural feature In contrast to the large number of structures known for Os-P and Ru-P clusters, there are very few examples of clusters containing osmium or ruthenium with the heavier group 15 elements Many of the clusters containing a heavier group 15 element have them present as a... potential with increasing cluster size is another reason for the interest in cluster compounds When several transition metal atoms bind together, they tend to agglomerate in order to form the maximum number of metal-metal bonds, instead of forming chains 3 Main group- transition metal cluster compounds have been of great interest in the field of organometallic chemistry due to their unique structural and reactivity. .. structural and reactivity patterns The introduction of main group elements into a transition metal cluster framework enhances its polarity and changes the reactivity chemistry from that of the homometallic system; this is the interplay between the differing properties of the elements Furthermore, there is a steady movement towards the view that the main group elements in many such compounds should be better... Os3(CO)10(µ-ER)2, G, in two isomeric forms G1 and G2 46-48 In line with our general interest in transition metal-main group element mixed-metal clusters, we embarked on an exploration of the chemistry of 1 with some compounds of the group 16 elements Os Os ER G1 Os ER Os Os Os H3CCN R2E2 or/ and or NCCH3 R = Ph or Me E = S, Se or Te Os Os ER G2 Os Os Os H3CCN E R Os Scheme 1.3 Reaction of triosmium clusters and R2E2... that osmium- antimony clusters often show novel reactivity patterns which are different from the phosphorus or arsenic analogues One of the more well-studied cluster among these is Os3(CO)10(µ-H)(µ -SbPh2), 1, which can be obtained in reasonable yield from the salt elimination reaction of [Os3(µ-H)(CO)10(µ-CO)]- and an excess of Ph2SbCl in THF (Scheme 1.1) Two other products, Os3(CO)10(µ -SbPh2)2 , A, with. .. electronic effects of the substituents.10-11 The Ru-Ru bond lengths for the clusters in Table 1.1 span the range 2.731(1) to 3.1700(5) Å, i.e., a spread of 0.44 Å; the corresponding range for the OsOs bond is 2.7524(6) to 3.2332(12) Å, i.e., a spread of 0.48 Å The bridging hydride is an example of ligand effects on metal-metal bond lengths The presence of a bridging hydride tends to lengthen the Os-Os bond,... for the formation of 4a and 4b p.22 Scheme 4.1 Synthesis of organometallic clusters containing Ln-M bonds through ligand assistance p.40 Scheme 4.2 Synthesis of organometallic clusters containing Ln-M bonds through ligand assistance p.41 Scheme 4.3 Synthetic scheme p.42 xiv Chapter 1 Organometallic chemistry of clusters containing osmium or ruthenium and the heavier group 15 elements Organometallic clusters... difference in structure is presumably due to the additional Ph group for E = P or Sb; bending of the EPh 2 group out of the Os3Sb plane would not meet with steric hindrance from the axial carbonyl on the unbridged osmium (eg., CO(34) in figure 2.3).6 As may be expected, the Os-E bond length increases, and the Os-E-Os bond angle decreases, with increasing size of the atom E (covalent radii: S = 1.05 Å; P ... react with group 16 elements, in contrast, the reactivity of antimony- containing osmium clusters with group 16 elements has not been explored In this section, the synthesis and reactivity of the cluster. .. Os3(CO)10(µ-H)(µ -SbPh2), with some group 16 compounds are reported 2.1 Reaction of Os3(CO)10(µ-H)(µ -SbPh2) with REER and PhEH The cluster Os3(CO)10(µ-H)(µ -SbPh2), reacted with an equimolar of REER or... Reaction of (THF)Yb[(C9H7CH2CH2)PPh2]3 with Os3(CO)11(NCMe) p.46 4.5 References Appendices p.47 CDROM iii ABSTRACT The reaction of the osmium- antimony cluster Os3(CO)10(µ-H)(µ -SbPh2) with the group 16