The chemistry of [M3(CO)10(μ-dppm)](M=Ru, Os): Activating and maintaining the trinuclear core

Reactions of diphosphine-stabilized Os3 clusters with triphenylantimony: syntheses and structures of new antimony-containing Os3 clusters via Sb-Ph bond cleavage

The reactivity of the trimetallic clusters [Os₃(CO)₁₀(μ-dppm)] [dppm = bis(diphenylphosphino)methane] and [HOs₃(CO)₈{μ₃-Ph₂PCH₂PPh(C₆H₄-μ₂,σ¹)}] with triphenylantimony (SbPh₃) has been examined. [Os₃(CO)₁₀(μ-dppm)] reacts with SbPh₃ in refluxing toluene to yield three new triosmium clusters [Os₃(CO)₉(SbPh₃)(μ-dppm)] (1), [HOs₃(CO)₇(SbPh₃){μ₃-Ph₂PCH₂PPh(C₆H₄-μ₂,σ¹)}] (2), and [HOs₃(CO)₇(SbPh₃)(μ-C₆H₄)(μ-SbPh₂)(μ-dppm)] (3). [HOs₃(CO)₈{μ₃-Ph₂PCH₂PPh(C₆H₄-μ₂,σ¹)}] reacts with SbPh₃ (excess) at room temperature to afford [Os₃(CO)₈(SbPh₃)(η¹-Ph)(μ-SbPh₂)(μ-dppm)] (4) as the sole product. A series of control experiments have also been conducted to establish the relationship between the different products. The molecular structure of each product has been determined by single-crystal X-ray diffraction analysis, and the bonding in these new clusters has been investigated by electronic structure calculations.

A new synthetic route for the preparation of [Os3(CO)10(μ-OH)(μ-H)] and its reaction with bis(diphenylphosphino)methane (dppm): syntheses and X-ray structures of two isomers of [Os3(CO)8(μ-OH)(μ-H)(μ-dppm)] and [Os3(CO)7(μ3-CO)(μ3-O)(μ-dppm)]

The triosmium cluster [Os₃(CO)₁₀(μ-OH)(μ-H)] containing bridging hydride and hydroxyl groups at a common Os–Os edge was obtained in good yield (ca. 75%) from the hydrolysis of the labile triosmium cluster [Os₃(CO)₁₀(NCMe)₂] in THF at 67 °C. [Os₃(CO)₁₀(μ-OH)(μ-H)] reacts with dppm at 68 °C to afford the isomeric clusters 1 and 2 with the general formula [Os₃(CO)₈(μ-OH)(μ-H)(μ-dppm)] that differ by the disposition of bridging dppm ligand. Cluster 1 is produced exclusively from the reaction of [Os₃(CO)₁₀(μ-OH)(μ-H)] with dppm in CH₂Cl₂ at room temperature in the presence of added Me₃NO. Heating cluster 1 at 81 °C furnishes 2 in a process that likely proceeds by the release of one arm of the dppm ligand, followed by ligand reorganization about the cluster polyhedron and ring closure of the pendent dppm ligand. The oxo-capped [Os₃(CO)₇(μ₃-CO)(μ₃-O)(μ-dppm)] (3) has been isolated starting from the thermolysis of either 1 or 2 at 139 °C. Reactions of [Os₃(CO)₁₀(μ-dppm)] with ROH (R = Me, Et) in the presence of Me₃NO at 80 °C furnish [Os₃(CO)₈(μ-OH)(μ,η¹,κ¹-OCOR)(μ-dppm)] (4, R = Me; 5, R = Et). Clusters 1–5 have been characterized by a combination of analytical and spectroscopic studies, and the molecular structure of each product has been established by X-ray crystallography. The bonding in these products has been examined by electronic structure calculations, and cluster 1 is confirmed as the kinetic product of substitution, while cluster 2 represents the thermodynamically favored isomer.

The cluster [Os₃(CO)₁₀(μ-OH)(μ-H)] was obtained in 75% from the hydrolysis of [Os₃(CO)₁₀(NCMe)₂].

New molecular architectures containing low-valent cluster centres with di- and trimetalated 2-vinylpyrazine ligands: synthesis and molecular structures of Ru5(CO)15(μ5-C4H2N2CH[double bond, length as m-dash]CH)(μ-H)2 and Ru8(CO)24(μ7-C4H2N2CH[double bond, length as m-dash]C)(μ-H)3

Reaction of 2-vinylpyrazine with Ru₃(CO)₁₂ results in multiple C-H bond activations to afford penta- and octa-ruthenium clusters, Ru₅(CO)₁₅(μ₅-C₄H₂N₂CH[double bond, length as m-dash]CH)(μ-H)₂ (2) and Ru₈(CO)₂₄(μ₇-C₄H₂N₂CH[double bond, length as m-dash]C)(μ-H)₃ (3), in which a Ru₃ sub-unit is linked to Ru₂ and Ru₅ centres via di- and tri-metalated 2-vinylpyrazine ligands, exhibiting novel coordination modes including the loss of ring aromaticity in 2. The bonding of 2 and the mechanism for the fluxional behaviour of the hydrides have been examined by electronic structure calculations.

Synthesis of di- and trinuclear iridium polyhydride complexes surrounded by light-absorbing ligands

New di- and trinuclear iridium (Ir) penta- and hexahydride complexes containing light-absorbing diphosphine ligands have been developed. The trinuclear Ir complex possessed a higher absorption coefficient (standardized per Ir) than that of the parent mononuclear Ir complex, indicating the assembly effect. The trinuclear complex showed high reactivity toward catalytic hydrogenation of diphenylacetylene under mild conditions, and the reaction was considerably accelerated under photoirradiation.

Alkyne activation and polyhedral reorganization in benzothiazolate-capped osmium clusters on reaction with diethyl acetylenedicarboxylate (DEAD) and ethyl propiolate

The reactivity of the face-capped benzothiazolate clusters HOs₃(CO)₉[μ₃-C₇H₃(R)NS] (1a, R = H; 1b, R = 2-CH₃) with alkynes has been investigated. 1a reacts with DEAD at 67 °C to furnish the isomeric alkenyl clusters Os₃(CO)₉(μ-C₇H₄NS)(μ₃-EtO₂CCCHCO₂Et) (2a and 3a). X-ray crystallographic analyses of 2a and 3a have confirmed the stereoisomeric relationship of these products and the regiospecific polyhedral expansion that follows the formal transfer of the hydride to the coordinated alkyne ligand in HOs₃(CO)₉(μ-C₇H₄NS)(η²-DEAD). The significant structural differences between the two isomers, as revealed by the solid-state structures, derives from the regiospecific cleavage of one of the three Os-Os bonds in the intermediate alkenyl cluster Os₃(CO)₉(μ-C₇H₄NS)(η¹-EtO₂CCCHCO₂Et), which follows hydride transfer to the coordinated alkyne ligand in the pi compound HOs₃(CO)₉(μ-C₇H₄NS)(η²-DEAD). Control experiments confirm the reversibility of the reaction leading to the formation of 2a and 3a. Whereas heating either isomer in refluxing THF or benzene affords a binary mixture containing 2a and 3a, thermolysis in refluxing toluene leads to the activation of the alkenyl ligand and formation of the new cluster Os₃(CO)₉(μ-C₇H₄NS)(μ₃-EtO₂CCCH₂) (4). 4 was independently synthesized from 1a and ethyl propiolate at room temperature. The computed mechanisms that account for the formation of 2a and 3a are presented, along with the mechanism for the reaction of 1a with ethyl propiolate to give 4.

[μ2-Bis(di-phenyl-phosphan-yl)hexa-ne]bis-[undeca-carbonyl-triangulo-triruthenium(3 Ru-Ru)] hexane monosolvate: crystal structure and Hirshfeld surface analysis

In the title cluster complex hexane solvate, [Ru6(C30H32P2)(CO)22]·C6H14, two Ru3(CO)11 fragments are linked by a Ph2P(CH2)6PPh2 bridge with the P atoms equatorially disposed with respect to the Ru3 triangle in each case; the hexane solvent mol-ecule is statistically disordered. The Ru⋯Ru distances span a relatively narrow range, i.e. 2.8378 (4) to 2.8644 (4) Å. The hexyl chain within the bridge has an all-trans conformation. In the mol-ecular packing, C-H⋯O inter-actions between cluster mol-ecules, and between cluster and hexane solvent mol-ecules lead to a three-dimensional architecture. In addition, there are a large number of C≡O⋯π(arene) inter-actions in the crystal. The importance of the carbonyl groups in establishing the packing is emphasized by the contribution of 53.4% to the Hirshfeld surface by O⋯H/H⋯O contacts.

A sulfur mimic of 1,1-bis(diphenylphosphino)methane: a new ligand opens up

Tetrasubstituted-diphosphine monosulfides “open up” and coordinate to Ru(ii) as chelating bis(ditertiaryphosphino)thioethers.