The synthesis ~nd .study of the dynamic behaviour of (Il-H)4Ru4 (CO)9 (HC (PPhz)3) are described. The X-ray structural determination shows this cluster to be chiral, the asymmetry arising from a helical array of phenyl groups on the tripod ligand. Core structure A, (Du symmetry) bas hydride ligands bridging four edges of the tetrahedron so that two opposite In a recent study t we showed that the ligand HC(PPhlh edges remain vacant. This has been found for (hereafter tripod) could serve to complex three metal atoms (JI.-H).Ru.(CO)12 3, (JI.-H).Ru.(CO)uP(OMeh ., and in a triangular array e. g. "cap" a triangular face of clusters (JI.-H).Ru.(CO)to(PPb3h 3. Core structure B (C. symmetry) such as M.(CO)ll (M;"Co, Rh). We found that the analo­ has been established for both isomers ~. 6 of gous complex, H.Ru.(CO)12 also reacted 1 smoothly with (J.l-H).Ru. (CO) '0 (Ph2PCH2CH2PPhJ. Since the tripod tripod to yield the complex H.Ru.(CO)9(tripod). The spec­ ligand imposes facial substitution (assuming all phosphorus troscopic data (IR, NMR) of this molecule, altbough consis­ atoms are bound), we anticipated the limiting low tempera­ tent with a capped structure, sbowed some unexpected featu­ ture spectrum of the hydride region to show either a 2H : 2H res wbich we decided to investigate further. pattern (A) or a 1H : 2 H : 1H pattern (B). However four separate resonances are observed which prompted us to inves­ There have been several structural and spectroscopic stu­ tigate in more detail the spectroscopy and carry out an X-ray dies of phosphine substituted derivatives of H.Ru.(CO)12' diffraction analysis of this compound Interest has mainly focused on the position of the hydride ligands on the cluster surface and the mechanism of their intramolecular site exchange. Two structural forms for the M.H.. core have been established which are shown schemati­ cally below.

A novel tridentate hemilabile ligand 2 containing phosphine, imine and pyridyl donor groups has been prepared in analogy with the synthesis of the known related ligand 1. The reaction of 1 or 2 with [Rh(COE)(2)Cl](2) resulted in the formation of the neutral complexes [Rh(L)Cl]. By a method using [M(diene)Cl](2) as starting material, cationic complexes of the type [M(diene)(L)]X were also obtained (M = Rh, diene = NBD, L = 1, 2; M = Ir, diene = COD, L = 1; X = BF4, OTf). A comparative study of the catalytic activity of the new complexes towards the hydrogenation of various olefins has been reported. In particular, the catalysts of the type [Rh(L)Cl] are remarkably active when prepared in situ, especially for the reduction of hindered olefins. (C) 2002 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.

The reaction of the 3,6-bis (2′-pyridyl) pyridazine (dppn) ligand, with one and two equivalents of [Rh (CO) 2Sn] (PF6) , (s = THF) , yields respectively the mononuclear complex [Rh (CO) 2 (dppn) ] (PF6) 1 and the binuclear complex [Rh2 (CO) 4 (dppn) ] (PF6) 2 3. Furthermore, the reaction of 1 with PPh3 results in a substitution reaction to give [Rh (CO) (dppn) (PPh3) 2] (PF6) 2. The unsaturated complex 3 reacts with the monodentate phosphine PPh3 to yield a mixture of the known compound [Rh (CO) 2 (PPh3) 2] (PF6) and of the mononuclear [Rh (CO) (dppn) (PPh3) ] (PF6) 4, the crystal structure of which was established by X-ray diffraction. Moreover, 3 reacts with the bis (diphenylphosphino) methane (dppm) ligand in a 1 : 2 ratio to form the binuclear A-frame complex [Rh2 (CO) 2 (dppn) (μ-dppm) 2] (PF6) 2 5. However, the reaction of 3 with excess dppm (1 : 4 ratio) gives the known complex [Rh (CO) (dppm) 2] (PF6) 6.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Treatment of [M(COD){HC(PPh2)3}]BF4 (M = Rh, Ir; 1a, 1b) with 1 equiv of the complex [Au(PPh3)(THF)]BF4 in THF/CH2Cl2 at room temperature afforded the binuclear species [M(COD){HC(PPh2)3}Au(PPh3)](BF4)2 (M = Rh, Ir;2a, 2b). The molecular structure of 2a showed both rhodium and gold bound to a single tripod ligand in a clamped arrangement with a rhodium to gold separation of 5.431 (1) angstrom. The reactions of molecular hydrogen and carbon monoxide with these complexes have been studied. When the mononuclear species [Rh(COD){HC(PPh2)3}]BF4 (1a) was treated with [Cu(CH3CN)4]BF4 in acetonitrile, the heterobinuclear complex [Rh(CH3CN)3Cu{HC(PPh2)3}](BF4)2 (6) was obtained. 6 transforms in CH2Cl2/THF to give the trinuclear species [RhCu2{HC(PPh2)3}2(THF)2(CH3CN)2](BF4)2(F) (7) for which an X-ray molecular structure was also determined. In the structure the rhodium lies on a center of symmetry, the two copper(I) ions each being 5.353 (4) angstrom distant from rhodium. The tetracoordinate planar arrangement of four phosphorus atoms about the rhodium results from the coordination of two tripod ligands, each providing two donor sites, leaving one phosphorus atom on each tripod to bind each Cu(I), which possesses a trigonal-planar coordination geometry. The catalytic properties of these new complexes for the hydrogenation of olefins have been briefly compared in order to probe the effect of the presence of the coinage metal on such processes. 2a.2H2O.Et2O crystallizes in the monoclinic space group P2(1)/n (No. 14), a = 20.704 (5) angstrom, b = 13.686 (3) angstrom, c = 23.573 (5) angstrom, beta = 109.42 (2)-degrees, and Z = 4. The structure was refined to R = 6.4 and R(w) = 10.7%, using 6924 reflections. 7.2C6H6 crystallizes in the triclinic space group P1BAR (No.2), a = 13.544 (3) angstrom, b = 14.741 (3) angstrom, c = 13.156 (3) angstrom, alpha = 101.69 (2)-degrees, beta = 98.29 (2)-degrees, gamma = 62.76 (2)-degrees, and Z = 1. The structure was refined to R = 10.1 and R(w) = 13.6%, using 4437 reflections.

The one-electron-oxidized cluster [Co4(CO)9{HC(PPh2)3}]˙+ reacts with PPh3 and P(OMe)3. The reaction mechanisms involve the substitution of CO by PR3. The P(OMe)3 substituted cluster is stable, whereas the PPh3 substituted cluster undergoes an intramolecular electron transfer which regenerates the initial cluster. A general reaction scheme is proposed for the one-electron-oxidized and the one-electron-reduced cluster.

The tripod ligand HC(PPh2)3 reacts with Mo(CO)3(CH3CN)3 yielding Mo(CO)3(CH3CN)(HC(PPh2)3). Reaction of this Mo0 complex with [Rh(CO)2Cl]2 gives unexpectedly the tetranuclear species [Rh2(CO)(HC(PPh2)3)]2(μ-Cl)+3 (3) which crystallizes as the Rh(CO)2Cl−2 salt (3a). This complex crystallizes in the monoclinic space group P21/c with Z = 4, with all dimensions a = 19.685(3), b = 19.524(3), c = 22.657(4) Å, and β = 96.96(2)°. A direct route to the PF−6 salt of 3 (3b) is also presented. The 31P NMR data show 3a and 3b to be identical and that the tetranuclear structure is retained in solution, i.e. two units of binuclear RhI species bridged by three chlorine atoms. In each binuclear unit, the tripod ligand spans two RhI which are linked directly by a metal-metal bond (RhRh = 2.696 Å).

The complexes M(1,5 cyclooctadiene)(HC(PPh2)3)+BF4− (M = Rh, Ir) have been synthesized characterized. The 31P 1H NMR spectra show that in the ground-state structure the tripod ligand forms a bidentate chelate with the metal, the third phosphorus atom remaining uncoordinated. However, VTNMR studies show a rapid exchange process to be occurring at room temperature causing equilibration of all the phosphorus nuclei as well as the vinylic and methylenic protons of the diene ligand. An associative intramolecular exchange mechanism is proposed.

AbstractThe ligands L in (III) may be triflate ions in the solid state.

Starker Donor‐Acceptor‐Charakter kennzeichnet die Rh–Rh‐Bindung in 1 mit zwei koordinativ ungesättigten, benachbarten RhI‐Zentren. Das „offenere”︁, nahezu quadratisch‐pyramidal koordinierte Rh‐Zentrum wird dadurch so elektronenarm, daß sich CO bei der Reaktion mit 1 (L = MeCN) an das quadratisch koordinierte Rh‐Zentrum addiert. Ein zu 1 analoger Komplex katalysiert Hydrierungen.magnified image

A. A. Bahsoun, J. A. Osborn, P. H. Bird, D. Nucciarone and A. V. Peters, J. Chem. Soc., Chem. Commun., 1984, 72 DOI: 10.1039/C39840000072

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComplexation of triangular faces of tetranuclear clusters by the tripod ligands HC(PPh2)3 and HC(AsPh2)3. Molecular structure of (.pi.-toluene)[HC(PPh2)3]Co4(CO)6A. A. Bahsoun, J. A. Osborn, C. Voelker, J. J. Bonnet, and G. LavigneCite this: Organometallics 1982, 1, 9, 1114–1120Publication Date (Print):September 1, 1982Publication History Published online1 May 2002Published inissue 1 September 1982https://doi.org/10.1021/om00069a002Request reuse permissionsArticle Views117Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (962 KB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

AbstractEine Lösung des Titelliganden (I) in Toluol und Rh4(CO)" in Hexan reagieren unter Argon zu dem Cluster‐Komplex (IIa).