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Synthesis, characterisation and natural abundance Os NMR spectroscopy of hydride bridged triosmium clusters with chiral diphosphine ligands |
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| Authors: | Marc J. Stchedroff,Emilio Rodriguez,Jark Bö ttcher,Ebbe Nordlander,Magda Monari |
| Affiliation: | a Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK b Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden c Dipartimento di Chimica “G. Ciamician”, Università degli Studi di Bologna, Via Selmi 2, I-40126 Bologna, Italy d Department of Chemistry, University Science Laboratories, University of Durham, South Road, Durham DH1 3LE, UK |
| Abstract: | Treatment of [Os3(μ-H)2(CO)10] with the chiral diphosphines BINAP, tolBINAP [(R)-2,2′-bis(di-4-tolylphosphino)-1,1′-binaphthyl], DIOP [(4R,5R)-(−)-O-isopropenylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane] affords [Os3(μ-H)2(CO)8(μ-L)] (L = BINAP (1), tolBINAP (2), DIOP (4)) in high yield. The X-ray structures for 1, 2 and 4 are reported, and structural and spectroscopic comparisons are made between these clusters and [Os3(μ-H)2(CO)8(μ-L)] (L = dppm (5), dppe (6), dppp (7)) which were synthesised similarly. Compounds 5 to 7 were previously synthesised by hydrogenation of 1,2-[Os3(CO)10(μ-L)] but the route from [Os3(μ-H)2(CO)10] is preferable. The H-bridged Os?Os distances are similar in 1, 2 and 4 indicating that these species are formally unsaturated 46-electron clusters. The P?P distances vary from 4.24 to 4.30 Å in 1 and 2, respectively, to 4.53 Å in 4 and there are related changes in the angles associated with the ligand set around the H-bridged osmium atoms. Introduction of the diphosphine ligands completely suppresses the ability to add CO, to insert acetylene to form a μ-η1,η2-vinyl compound, and to exchange hydride ligands with styrene-d8, which are reactions characteristic of [Os3(μ-H)2(CO)10]. Clusters 2 and 5-7 were also used to examine the potential of natural abundance 187Os NMR spectroscopy through techniques based on inverse detection by HMQC, HSQC and HMBC spectroscopy. |
| Keywords: | Cluster Osmium Chiral phosphine NMR |
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