The reaction of metal carbonyl compounds with group 6 and 8 metallaboranes led us to report the synthesis and structural characterization of several novel mixed-metal chalcogenide tetrahedral clusters. Thermolysis of arachno-[(Cp∗RuCO)2B2H6], 1, and [Os3(CO)12] in the presence of 2-methylthiophene yielded [Cp∗Ru(CO)2(μ-H){Os3(CO)9}S], 3, and [Cp∗Ru(μ-H){Os3(CO)11}], 4. In a similar fashion, the reaction of [(Cp∗Mo)2B5H9], 2, with [Ru3(CO)12] and 2-methylthiophene yielded [Cp∗Ru(CO)2(μ-H){Ru3(CO)9}S], 5, and conjuncto-[(Cp∗Mo)2B5H8(μ-H){Ru3(CO)9}S], 6. Both compounds 3 and 5 can be described as 50-cve (cluster valence electron) mixed-metal chalcogenide clusters, in which a sulfur atom replaces one of the vertices of the tetrahedral core. Compounds 3 and 5 possess a [M3S] tetrahedral core, in which the sulfur is attached to an exo-metal fragment, unique in the [M3S] metal chalcogenide tetrahedral arrangements. All the compounds have been characterized by mass spectrometry, IR, and 1H, 11B and 13C NMR spectroscopy in solution, and the solid state structures were unequivocally established by crystallographic analysis of compounds 3, 5 and 6. © 2014 the Partner Organisations.

Sundargopal Ghosh

Department Of Chemistry

Kuppusamy Yuvaraj

Babu Varghese

Metal chalcogenide

METAL FRAGMENTS

Tetrahedral clusters

Fulltext

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IIT Madras

Dalton Transactions

To build upon our earlier results of heterometallic metallaboranes employing metal carbonyls, we performed the reaction of nido-[(Cp*Rh)2B3H7] (1) (nido-1) with [M(CO)5·THF] (M = Mo or W) that yielded the trimetallic metallaborane clusters [(Cp*Rh)2M(CO)3(μ-CO)(μ3-BH)(B2H4)] (3: M = Mo; 4: M = W) having a capped borylene fragment and trimetallic triply bridging borylene complexes [(Cp*Rh)2(μ3-BH)(μ-CO)M(CO)5] (5: M = Mo; 6: M = W). The chemistry of trimetallic triply bridging borylene complexes (5 and 6) were explored with Lewis bases such as tert-butyl isocyanide and bisphosphine ligands. Photolysis of 5 and 6 with tert-butyl isocyanide yielded [(Cp*Rh)2(μ3-BH)(μ-CO)M(CO)4(CN-tBu)] (7: M = Mo; 8: M = W) and with phosphines, PPh2(CH2)nPPh2 (n = 1, 2) they resulted in the formation of [(Cp*Rh)2(μ3-BH)(μ-CO)M(CO)4((PPh2)2(CH2)n)] (9: n = 1, M = Mo; 10: n = 1, M = W; 11: n = 2, M = Mo; 12: n = 2, M = W). All the new compounds have been characterized in solution by mass spectrometry and NMR spectroscopic techniques. The structural aspects were unambiguously established by X-ray crystallographic analysis of 3–4 and 7–10. © 2018 Elsevier B.V.

Journal of Organometallic Chemistry

Synthesis and ligand substitution of tri-metallic triply bridging borylene complexes

Thermolysis of [Cp*Ru(µ-H)BH(L)2] (Cp* = η5-C5Me5, L = C7H4NS2), (1) with [Mn2(CO)10] led to the formation of a transmetallated complex [Mn(CO)3(µ-H)BH(L)2], (2) and a ruthenium-thiolate complex [(Cp*RuCO)2(L)2], (3) in moderate yields. Compound 2 can also be generated from a direct reaction of [Mn2(CO)10] and [NaBt] (Bt = dihydrobis(2-mercaptobenzthiazolyl)borate). Although all of our attempts to generate [M(CO)3(µ-H)2BHL] (M = Mn or Re) from the bis(σ-borate) complex [Cp*Ru(µ-H)2BHL] (L = C7H4NS2), (4) were failed, thermolysis of 4 with [Mn2(CO)10] yielded a σ-borane complex [Cp*RuCO(µ-H)BH2L], (5) and a mixed-metal thiolate complex [(Cp*RuCO)2(µ3-S)Mn(CO)3L], (6). Further, the reaction of compound 5 with [Mn2(CO)10] yielded heterocyclic thiolate complex [Cp*Ru(CO)2L)], (7). Thermolysis of 4 with [Re2(CO)10] does not yield any products. However, under photolytic conditions it led to the formation of mixed-metal thiolate complex [(Cp*RuCO)Re(CO)3(L)2], (8). All the compounds have been characterized by mass spectrometry, IR, 1H, 13C spectroscopy, and the X-ray structures of 2–3 and 5–8 were unequivocally established by crystallographic analysis. © 2016, The National Academy of Sciences, India.

Proceedings of the National Academy of Sciences India Section A - Physical Sciences

Synthesis and Structural Characterization of Group 7 and 8 Metal-Thiolate Complexes

The photolysis of [M2(CO)10] (M=Re or Mn) with BH3·thf at room temperature yields arachno-1 and 2, [(CO) 8M2B2H6] (1: M=Re, 2: M=Mn). Both the compounds show a butterfly structure with seven skeletal electron pairs and 42 valence electrons. This result presents a new method for general access to low-boron-content metal-boron compounds without the cyclopentadienyl ligand at the metal centers. This new synthetic route is superior to the existing procedures because it avoids the use of [LiBH4] and metal polychlorides, for which the synthesis is very tedious. Compound 1 catalyzes the cyclotrimerization of a series of internal and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes. The reactivity of 1 with alkynes demonstrates for the first time that the introduction of the [B 2H6] moiety into the [Re2(CO)10] framework significantly enhances the catalytic activity. Note that [Re 2(CO)10] catalyzes the same set of alkynes under harsh conditions over a prolonged period of time. Quantum-chemical calculations using DFT methods are applied to afford further insight into the electronic structure, stability, and bonding of 1 and 2. All the compounds are characterized by IR and 1H, 11B, and 13C NMR spectroscopy, and the geometry of 1 is established unambiguously through crystallographic analysis. Arachno compounds: Room-temperature UV photolysis of [Re2(CO) 10] with BH3·thf yielded arachno-[(CO) 8Re2B2H6], which catalyzed the cyclotrimerization of various internal and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes (see figure). Copyright © 2014 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

ChemPlusChem

Metallaboranes from metal carbonyl compounds and their utilization as catalysts for alkyne cyclotrimerization

Room temperature photolysis of [(Cp*RuCO)2BH4(Bcat)], 3, generated from the reaction of arachno-[(Cp*RuCO)2B2H6], 1, with HBcat (cat = 1,2-O2C6H4), yielded a rare homodinuclear bridged-boryl complex, [(Cp*Ru)2(μ-H)(μ-CO)(μ-Bcat)], 4, confirmed by X-ray diffraction. © 2013 The Royal Society of Chemistry.

Journal of the Chemical Society. Dalton Transactions

A fine tuning of metallaborane to bridged-boryl complex, [(Cp*Ru)2(μ-H)(μ-CO)(μ-Bcat)] (cat = 1,2-O2C6H4; Cp* = η5-C5Me5)

Thermolysis of [(Cp*RuCO)2B2H6] (1; Cp* = η5-C5Me5) with [Ru 3(CO)12] yielded the trimetallaborane [(Cp*RuCO) 3(μ3-H)BH] (2) and a number of homometallic boride clusters: [Cp*RuCO{Ru(CO)3}4B] (3), [(Cp*Ru)2{Ru2(CO)8}BH] (4), and [(Cp*Ru)2{Ru4(CO)12}BH] (5). Compound 2 is isoelectronic and isostructural with the triply bridged borylene compounds [(μ3-BH)(Cp*RuCO)2(μ-CO){Fe(CO)3}] (6) and [(μ3-BH)(Cp*RuCO)2(μ-H)(μ-CO) {Mn(CO)3}] (7), where the [μ3-BH] moiety occupies the apical position. To test if compound 2 undergoes hydroboration reactions with alkynes, as observed with 6, we performed the reaction of 2 with the same set of alkynes under photolytic conditions. However, neither 2 nor 7 undergoes hydroboration to yield a vinyl-borylene complex. On the other hand, thermolysis of 6 with trimethylsilylethylene yielded the novel diruthenacarborane [1,1,7,7,7-(CO)5-2,3-(Cp*)2-μ-2,3-(CO) -μ3-1,2,3-(CO)-5-(SiMe3)-pileo-1,7,2,3,4,5-Fe 2Ru2C2BH] (8). The solid-state X-ray diffraction results suggest that 8 exhibits a pentagonal -bipyramidal geometry with one additional CO capping one of its faces. Cluster 3 is a boride cluster where boron is in the interstitial position of a square-pyramidal geometry, whereas compound 4 can be described as a tetraruthenium boride in which the Ru4 butterfly skeleton has an interstitial boron atom. Electronic structure calculations of compound 2 employing density functional theory (DFT) generate geometries in agreement with the structure determinations. The existence of a large HOMO-LUMO gap in 2 is in agreement with its high stability. Bonding patterns in the structure have been analyzed on the grounds of DFT calculations. Furthermore, the B3LYP-computed 11B and 1H chemical shifts for compound 2 precisely follow the experimentally measured values. All the compounds have been characterized by IR and 1H, 11B, and 13C NMR spectroscopy, and the geometries of the structures were unambiguously established by crystallographic analyses of 2-4 and 8. © 2013 American Chemical Society.

Organometallics

Chemistry of homo- and heterometallic bridged-borylene complexes

The reaction of nido-[1,2-(Cp*RuH)2B3H 7] (1 a, Cp*=Î·5-C5Me 5) with [Mo(CO)3(CH3CN)3] under mild conditions yields the new metallaborane arachno-[(Cp*RuCO) 2B2H6] (2). Compound 2 catalyzes the cyclotrimerization of a variety of internal- and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes. The reactivities of nido-1 a and arachno-2 with alkynes demonstrates that a change in geometry from nido to arachno drives a change in the reaction from alkyne-insertion to catalytic cyclotrimerization, respectively. Density functional calculations have been used to evaluate the reaction pathways of the cyclotrimerization of alkynes catalyzed by compound 2. The reaction involves the formation of a ruthenacyclic intermediate and the subsequent alkyne-insertion step is initiated by a [2+2] cycloaddition between this intermediate and an alkyne. The experimental and quantum-chemical results also show that the stability of the metallacyclic intermediate is strongly dependent on the nature of the substituents that are present on the alkyne. Everything changes but Ru: The reactivities of nido-[1,2-(Cp*RuH)2B3H7] and arachno-[(Cp*RuCO)2B2H6] with alkynes show that a change in geometry (nido to arachno) drives a change from alkyne-insertion to catalytic cyclotrimerization, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Chemistry - A European Journal

A mechanistic study of the utilization of arachno-diruthenaborane [(Cp*RuCO)2B2H6] as an active alkyne-cyclotrimerization catalyst

Reaction of [1,2-(Cp*RuH)2B3H 7](1;Cp* = η-C5Me5) with [Mo(CO) 3(CH3CN)3] yielded arachno-[(Cp*RuCO) 2B2H6](2), which exhibits a butterfly structure, reminiscent of 7 sep B4H10. Compound 2 was found to be a very good precursor for the generation of bridged borylene species. Mild pyrolysis of 2 with [Fe2(CO)9] yielded a triply bridged heterotrinuclear borylene complex [(μ3-BH) (Cp*RuCO)2(μ-CO){Fe(CO)3}] (3) and bis-borylene complexes [{(μ3-BH)-(Cp*Ru)(μ-CO)}2Fe 2(CO)5](4) and [{(μ3-BH)(Cp*Ru)Fe(CO) 3}2(μ-CO)] (5). In a similar fashion, pyrolysis of 2 with [Mn2(CO)10] permits the isolation of μ3-borylene complex [(μ3-BH)-(Cp*RuCO) 2(μ-H)(μ-CO){Mn(CO)3}] (6) . Both compounds 3 and 6 have a trigonal-pyramidal geometry with the μ3-BH ligand occupying the apical vertex, whereas 4 and 5 can be viewed as bicapped tetrahedra, with two μ3-borylene ligands occupying the capping position. The synthesis of tantalum borylene complex [(μ3-BH)(Cp*TaCO) 2(μ-CO){Fe(CO)3}] (7) was achieved by the reaction of [(Cp*Ta)2B4H8(μ-BH4)] at ambient temperature with [Fe2(CO)9]. Compounds 2-7 have been isolated in modest yield as yellow to red crystalline solids. All the new compounds have been characterized in solution by mass spectrometry; IR spectroscopy; and 1H, 11B, and 13C NMR spectroscopy and the structural types were unequivocally established by crystallographic analysis of 2-6. © 2010 Wiley-VCH Verlag GmbH &amp; Co. KGaA.

Journal	Data powered by TypesetDalton Transactions
Publisher	Data powered by TypesetRoyal Society of Chemistry
ISSN	14779226
Open Access	No