Caroline M. Martin

Synthesis of [M3H(CO)9(µ3-σ:η2:η2-C6H7)](M = Ru or Os). Molecular and crystal structure of the ruthenium cluster

The dienyl cluster compounds [M3H(CO)9(µ3-σ:η2:η2-C6H7)](M = Ru or Os) have been synthesised from [Os3H2(CO)10] or [M3(CO)10(MeCN)2](M = Ru or Os) with cyclohexa-1,3-diene. The molecular and crystal structure of [Ru3H(CO)9(C6H7)] has been established by single-crystal X-ray diffraction analysis: monoclinic, space group P21, a= 8.487(6), b= 12.031(3), c= 9.073(2)A, β= 92.43(4)° and Z= 2. The cyclohexadienyl ligand is involved in one σ and two π interactions with the metal triangle, while the H(hydride) ligand bridges the long Ru–Ru bond [3.052(1)A]. The other two Ru–Ru bond lengths are the same [2.837(1)A] and comparable to those observed in [Ru3(CO)9(µ3-η2:η2:η2-C6H6)]. The H(hyride) position afforded by the diffraction experiment has been compared with the result of potential-energy minimization procedures. The molecular organization within the lattice has been explored by means of atom–atom packing potential-energy calculations showing the presence of a network of C–H ⋯ O intermolecular hydrogen-bonding interactions.

The preparation, molecular structure and catalytic relevance of Ti(OSiPh3)4 and Ti(OGePh3)4

Abstract The preparation, spectroscopic characterisation and molecular structures of the four-coordinate, tetrahedral and monomeric compounds Ti(OSiPh3)4 and Ti(OGePh3)4 are presented and discussed. The catalytic inactivity of both of these compounds may be rationalised on the basis of the steric inaccessibility of the substrates to the Ti(IV) active sites, which are effectively shrouded by the bulky triphenyl groups.

Modelling the active sites of heterogeneous titanium-centred epoxidation catalysts with soluble silsesquioxane analogues

By synthesising and structurally characterising new soluble titanosilsesquioxanes, and by following the dynamics of epoxidation of cyclohexene in their presence, the tripodally anchored TiIV active sites in Ti–SiO2 heterogeneous catalysts are modelled structurally and catalytically.

Ruthenium cluster–[2.2]paracyclophane complexes

Abstract The last few years have seen a rapid expansion in the synthesis and characterisation of cluster–arene complexes. One arene ligand which has been found to be particularly versatile in cluster chemistry is [2.2]paracyclophane. In this article we review the chemistry of [2.2]paracyclophane clusters with regard to their synthesis, reactivity and structure.

New synthetic routes to [M3(CO)9(µ3-η2:η2:η2-C6H6)](M = Ru or Os)

A new, more convenient route to the benzene cluster [Ru3(CO)9(µ3-η2:η2:η2-C6H6)] directly from [Ru3(CO)12] has been established. Triruthenium dodecacarbonyl, [Ru3(CO)12], undergoes reaction with Me3NO–CH2Cl2 in the presence of cyclohexa-1,3-diene to give the clusters [Ru3H(CO)9(C6H7)] and [Ru3(CO)9(µ3-η2:η2:η2-C6H6)] in moderate yield. Triosmium dodecacarbonyl does not react similarly, but from the reaction of [Os3(CO)10(MeCN)2] with cyclohexa-1,3-diene a key intermediate compound [Os3(CO)10(η4-C6H8)] has been isolated and the solid-state structure of its acetonitrile solvate established by single crystal X-ray diffraction analysis at 150 K. The structure is monoclinic, space group P21/n, with a= 8.932(8), b= 17.387(13), c= 14.833(15)A, β= 105.69(6)° and Z= 4. The three osmium atoms form a regular triangle with a mean Os–Os distance of 2.877(12)A. Two osmium atoms, Os(1) and Os(2), are co-ordinated to four carbonyl ligands and one, Os(3), co-ordinates to two carbonyl ligands. All carbonyl ligands are terminal and approximately linear. The cyclohexadiene ligand is η4 co-ordinated to Os(3)via the 1,3-diene moiety, donating four electrons in total. On thermolysis, this compound is converted to [Os3H(CO)9(C6H7)] and then eventually to [Os3(CO)9(µ3-η2:η2:η2-C6H6)] by established means.

Multiple Coordination of Metal Atoms to Arenes: The Coordination of Six Ruthenium Atoms to Naphthalene‐1,8‐diyl in [Ru6(μ6‐C10H6)(μ3‐PPh)(CO)14]

Six ruthenium atoms are coordinated to the naphthalene-1,8-diyl ligand in the cluster [Ru6 (CO)14 (C10 H6 )(PPh)] through two Ru-C σ bonds, two η2 , and two η3 interactions (section of structure depicted on the right). The complex could, therefore, serve as a model for the chemisorption of naphthalene on a step-site on a (111) metal surface.

The synthesis of ruthenium and osmium carbonyl clusters with unsaturated organic rings

Abstract The reactivity of some ruthenium and osmium carbonyl clusters towards unsaturated organic ligands is described.

Preparation, characterisation, molecular and crystal structure of the octaruthenium arene clusters [Ru8H4(CO)18(η6-arene)](arene = C6H6 or C16H16)

Two octaruthenium arene clusters, [Ru8H4(CO)18(η-6-arene)](arene = C6H61 or C16H162), have been isolated from the thermolysis of [Ru3(CO)12] in octane, in the presence of cyclohexene (C6H10) or [2.2] paracyclophane (C16H16), respectively. Both compounds 1 and 2 have been characterised in the solid state by single-crystal X-ray diffraction and their molecular and crystal structures determined. The reaction of 2 with CO resulted in conversion to the carbido cluster [Ru6C(CO)14(µ3-η2:η2:η2-C16H16)] and [Ru3(CO)12] in quantitative amounts. Compound 1 did not react in the same way but yielded both [Ru4H4(CO)12] and [Ru4H2(CO)13].

Coordination of an anthracene-derived ligand through eight carbon atoms in the pentaruthenium bow-tie cluster [Ru5(CO)13(µ5-η1 : η2 : η3 : η3-C14H8-η1-PPh)]

The new pentaruthenium phenylphosphidoanthracene bow-tie cluster, [Ru5(CO)13(µ5-η1 : η2 : η3 : η3-C14H8-η1- PPh)], is prepared from the thermolysis of [Ru3(CO)12] and (9-anthracyl)diphenylphosphine, the crystal structure of which reveals a unique µ5-interaction of the ligand with the ruthenium cluster.

The cluster–surface analogy: the interaction of norbornene and norbornadiene with low-nuclearity ruthenium carbonyl clusters

The thermolysis of [Ru3(CO)12] with norbornene (nbe) and norbornadiene (nbd) leads to the tri- and tetra-ruthenium clusters, [(µ-H)2Ru3(CO)9(µ3-η1:η2:η1-C7H8)] 1 and [Ru4(CO)11(µ4-η1:η1:η2-η2-η2C7H6)] 2, respectively; the molecular structures of both clusters show organo-cluster interactions similar to the proposed organo-surface adsorption modes found on the Pt(111) surface, in which the bicyclic ring straddles a trimetallic face, coordinating through one alkenic bond and an agostic C–H⋯M interaction.