A series of agostic σ-borane/borate complexes have been synthesized and structurally characterized from simple borane adducts. A room-temperature reaction of [Cp∗Mo(CO)3Me], 1 with Li[BH3(EPh)] (Cp∗=pentamethylcyclopentadienyl, E=S, Se, Te) yielded hydroborate complexes [CpMo(CO)2(μ-H)BH2EPh] in good yields. With 2-mercapto-benzothiazole, an N,S-carbene-anchored σ-borate complex [Cp∗Mo(CO)2BH3(1-benzothiazol-2-ylidene)] (5) was isolated. Further, a transmetalation of the B-agostic ruthenium complex [Cp Ru(μ-H)BHL2] (6, L=C7H4NS2) with [Mn2(CO)10] affords a new B-agostic complex, [Mn(CO)3(μ-H)BHL2] (7) with the same structural motif in which the central metal is replaced by an isolobal and isoelectronic [Mn(CO)3] unit. Natural-bond-orbital analyses of 5-7 indicate significant delocalization of the electron density from the filled σB-H orbital to the vacant metal orbital. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sundargopal Ghosh

Department Of Chemistry

Rongala Ramalakshmi

Koushik Saha

Babu Varghese

Manganese

Molybdenum

Molybdenum compounds

Organic compounds

ruthenium

Synthesis (chemical)

2-MERCAPTO-BENZOTHIAZOLE

AGOSTIC BORANES

BORATE COMPLEXES

Carbenes

Natural bond orbital analysis

PENTAMETHYLCYCLOPENTADIENYL

Ruthenium complexes

Structural motifs

Ruthenium compounds

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IIT Madras

Chemistry - A European Journal

In an effort to isolate the chalcogen-rich niobium analogue of [(Cp∗Ta) 3 (μ-S) 3 (μ 3 -S) 3 BH], the room temperature reaction of [Cp∗NbCl 4 ] (Cp∗ = η 5 -C 5 Me 5 ) with Li[BH 2 S 3 ] was carried out. Although the objective of isolating the niobium analogue was not achieved, the reaction yielded a homocubane-type cluster [(Cp∗Nb) 3 (μ-S) 3 (μ 3 -S) 3 (μ-S)BH], 1, and a hexa-sulfido cluster [(Cp∗Nb) 3 (μ-S) 6 ], 2. Cluster 1 is a notable example of a homocubane-type cluster in which one of the vertices of the homocubane is missing. Compound 1 may be considered as a hypo-electronic cluster with an electron count of 64 cve (cve = cluster valence electrons), whereas compound 2 shows the presence of two doubly bridging η 1 -S around each Nb-Nb bond. On the other hand, the room temperature reaction of [Cp∗TaCl 4 ] with selenaborate ligand, [LiBH 2 Se 3 ], led to the formation of [(Cp∗Ta) 3 (μ-Se) 4 {μ-Se 2 (Se 2 )}], 3. Compound 3 is one of the rarest examples having a Ta 3 Se 6 core structure with a unique diselenide bridging fragment. The presence of a short Se-Se bond of this diselenide unit makes this molecule of further interest. All these compounds were characterized by 1 H, 11 B{ 1 H} and 13 C{ 1 H} NMR spectroscopy, infrared spectroscopy, mass spectrometry, and single-crystal X-ray crystallography. Density functional theory (DFT) calculations were carried out to provide insight into the bonding and electronic structures of these chalcogen-rich trimetallic clusters. © 2019 The Royal Society of Chemistry.

Dalton Transactions

Chalcogen stabilized trimetallic clusters: Synthesis, structures, and bonding of [(Cp∗M) 3 (E) 6+: M (BH) n ] (M = Nb or Ta; E = S or Se; M = 0 or 1 or 2; N = 0 or 1)

The complexes with fac-[M(CO)3]+ units of group-7 metals are interesting synthons for the development of target-specific drugs. Therefore, thermolysis reaction of Re2(CO)10 with various borate ligands have been investigated as a possible route to isolate bis(σ)borate complexes of rhenium. The reaction of trihydrobis(benzothiazol-2-yl)amideborate, Na[(H3B)bbza] (bbza = bis(benzothiazol-2-yl)amine) with Re2(CO)10 led to the formation of distorted octahedral rhenium complexes [(CO)2Re{N(C7H4NS)2}2], 1 and [(CO)2Re{N(C7H4NS)2}{C6H4N(Me)O}], 2. In order to increase the library of complexes containing fac-{M(CO)3}+ moieties as well as to check the lability of the metal–carbonyl bond, reactivity of manganese borate complexes [Mn(CO)3(μ-H)2BHNCSC6H4(NR)], 3 (R = NCSC6H4) and [Mn(CO)3{κ3-S,S′,H-H2B(mbz)2}], 6 (mbz = 2-mercapto-benzothiazolyl) with different ligands were carried out. Photolysis of 3 with excess phosphine ligands (PPh2Me or PMe2Ph) yielded manganese phosphine complexes [Mn(CO)2(PL2L′)2{N(C7H4NS)2}], (4a: L = Ph, L′ = Me; 4b: L = Me, L′ = Ph). Interestingly, the reaction of 3 with tBuNC yielded mono/bis(tBuNC)-substituted manganese borate complexes [Mn(μ-H)2(BHNCSC6H4)(NR)(CO)xLy], 5a–b (5a: x = 2, y = 1; 5b: x = 1; y = 2; L = tBuNC; R = NCSC6H4) and [Mn(μ-H)2BH{N(NCSC6H4)2}(CO)(tBuNC)2], 5c. Compounds 5b and 5c are structural isomers with a different coordination mode of the bbza ligand. Under similar reaction conditions, photolysis of 6 with PPh3 in toluene generated borate complex of manganese [Mn(CO2){κ3-S,S′,H-H2B(mbz)2}(PPh3)], 7. All the compounds were characterised by multi-nuclear NMR, IR spectroscopy and mass spectrometry. Density functional theory (DFT) calculations were carried out to investigate the bonding and electronic structures of these compounds. © 2019 Elsevier Ltd

Fulltext

Polyhedron

Fine tuning of reactivity and structure of bis(σ)borate and borate complexes of manganese by systematic ligand variation

The thermolysis of arachno-1 [(Cp*Ru) 2 (B 3 H 8 )(CS 2 H)] in the presence of tellurium powder yielded a series of ruthenium trithia-borinane complexes: [(Cp*Ru) 2 (η 1 -S)(η 1 -CS){(CH 2 ) 2 S 3 BH}] 2, [(Cp*Ru) 2 (η 1 -S)(η 1 -CS){(CH 2 ) 2 S 3 B(SMe)}] 3, and [(Cp*Ru) 2 (η 1 -S)(η 1 -CS){(CH 2 ) 2 S 3 BH}] 4. Compounds 2-4 were considered as ruthenium trithia-borinane complexes, where the central six-membered ring {C 2 BS 3 } adopted a boat conformation. Compounds 2-4 were similar to our recently reported ruthenium diborinane complex [(Cp*Ru){(η 2 -SCHS)CH 2 S 2 (BH 2 ) 2 }]. Unlike diborinane, where the central six-membered ring {CB 2 S 3 } adopted a chair conformation, compounds 2-4 adopted a boat conformation. In an attempt to convert arachno-1 into a closo or nido cluster, we pyrolyzed it in toluene. Interestingly, the reaction led to the isolation of a capped butterfly cluster, [(Cp*Ru) 2 (B 3 H 5 )(CS 2 H 2 )] 5. All the compounds were characterized by 1 H, 11 B{ 1 H}, and 13 C{ 1 H} NMR spectroscopy and mass spectrometry. The molecular structures of complexes 2, 3, and 5 were also determined by single-crystal X-ray diffraction analysis. © 2019 by the authors.

Inorganics

Synthesis of trithia-borinane complexes stabilized in diruthenium core: [(Cp*Ru) 2 (η 1 -S)(η 1 -CS){(CH 2 ) 2 S 3 BR}] (R = H or SMe)

The synthesis and reactivity of ruthenium complexes containing an anionic boron based ligand, supported by mercapto-benzothiazolyl heterocycles are presented. Specifically, the reaction of [(η6-p-cymene)Ru{P(OMe)2OR}Cl2], (1a: R = Me; 1b: R = H) with [H2B(mbz)2]- (mbz = 2-mercaptobenzothiazolyl) at room temperature afforded a series of borate complexes, namely [(L)Ru{κ3-H,S,S′-H2B(L)2}P(O)(OMe)(HL)], 2, [Ru{κ3-H,S,S′-H2B(L)2}2], 3 and [(κ2-N,S-L)P(OMe)3Ru{κ3-H,S,S′-H2B(L)2}], 4a; (L = C7H4NS2). The pivotal feature of 2 is the coordination of the Ru centre with a phosphorus atom of secondary phosphine oxide and mercapto-benzothiazolyl ligands. On the other hand, 3 features dual Ru⋯H-B interactions between Ru and B-H bonds of [H2B(mbz)2]-. Interestingly, along with 3, compound [(κ2-N,S-L)P(OPh)3Ru{κ3-H,S,S′-H2B(L)2}], 4b (L = C7H4NS2), was isolated upon treatment of the same borate with [(η6-p-cymene)RuCl2P(OPh)3], 1c, which is stabilized by δ-B-H interactions and one phosphite ligand. Furthermore, compound 3 promptly reacts with P(OR)3 to generate [(OR)3PRu-{κ2-S,S′-H2B(L)2}{κ3-H,S,S′-H2B(L)2}], (5a: R = Me, 5b: R = Ph; L = C7H4NS2) by breaking one of the Ru⋯H-B interactions. Upon heating, compound 5a converts into [(OMe)2OPRu{κ2-S,S′-HB(L)2}{κ3-H,S,S′-H2B(L)2}], 6a (L = C7H4NS2) by release of methane gas. Compound 6a is a unique example wherein the boron atom of the borate ligand is bound to an oxygen atom of the phosphite unit. In contrast, the thermolysis of 3 with PR2R′ yielded [Ru{κ3-H,S,S′-H2B(L2)}(PR2R′)2(L)], (7a: R = Me, R′ = Ph; 7b: R = Ph; R′ = Me; L = C7H4NS2), respectively, revealing the incorporation of two triphosphine ligands in the coordination sphere of ruthenium. Density functional theory (DFT) calculations were undertaken to provide an insight into the electronic structures of the complexes. © 2019 The Royal Society of Chemistry.

Mercapto-benzothiazolyl based ruthenium(ii) borate complexes: Synthesis and reactivity towards various phosphines

The field of diborinane is sparsely explored area, and not many compounds are structurally characterized. The room-temperature reaction of [{Cp∗RuCl(μ-Cl)} 2 ] (Cp∗ = η 5 -C 5 Me 5 ) with Na[BH 3 (SCHS)] yielded ruthenium dithioformato [{Cp∗Ru(μ,η 3 -SCHS)} 2 ], 1, and 1-thioformyl-2,6-tetrahydro-1,3,5-trithia-2,6-diborinane complex, [(Cp∗Ru){(η 2 -SCHS)CH 2 S 2 (BH 2 ) 2 }], 2. To investigate the reaction pathway for the formation of 2, we carried out the reaction of [(BH 2 ) 4 (CH 2 S 2 ) 2 ], 3, with 1 that yielded compound 2. To the best of our knowledge, it appears that compound 2 is the first example of a ruthenium diborinane complex where the central six-membered ring [CB 2 S 3 ] adopts the chair conformation. Furthermore, room temperature reaction of 1 with [BH 3 ·thf] resulted in the isolation of agostic-bis(σ-borate) complex, [Cp∗Ru(μ-H) 2 BH(S-CH=S)], 4. Thermolysis of 4 with trace amount of tellurium powder led to formation of bis(bridging-boryl) complex, [{Cp∗Ru(μ,η 2 -HBS 2 CH 2 )} 2 ], 5, via dimerization of 4 followed by dehydrogenation. Compound 5 can be considered as a bis(bridging-boryl) species, in which the boryl units are connected to two ruthenium atoms. Theoretical studies and chemical bonding analyses demonstrate the reason for exceptional reactivity and stability of these complexes. © 2019 American Chemical Society.

Inorganic Chemistry

Trithia-diborinane and Bis(bridging-boryl) Complexes of Ruthenium Derived from a [BH 3 (SCHS)] ? Ion

A series of novel Cp*-based (Cp*=η5-C 5Me5) agostic, bis(σ-borate), and boratrane complexes have been synthesized from diruthenium and dirhodium analogues of pentaborane(9). The synthesis and structural characterization of the first neutral ruthenadiborane(6) analogue are also reported. This new route offers a very efficient method for the isolation of bis(σ-borate) and agostic complexes from diruthenapentaborane(9). © 2014 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Angewandte Chemie - International Edition

Reactivity of diruthenium and dirhodium analogues of pentaborane(9): Agostic versus boratrane complexes

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)

A neutral metallaborane comprising a Rh4B12 polyhedron with icosioctahedron geometry with 16 vertices and 28 triangular faces was prepared (see structure; Rh: red, B: green). The cage has the shape of a 12-membered truncated tetrahedron with four capped hexagonal faces. © 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Boron beyond the icosahedral barrier: A 16-vertex metallaborane

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.

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

C-H activation of arenes and heteroarenes has been achieved by a hydrogen rich tantalaborane cluster [(Cp*Ta)2B5H 11] that leads to the formation of C-H functionalized products. Furthermore, we examined the reaction of substituted thiophene and pyrrole derivatives with tantalaborane which provided a convenient and efficient route to regio-defined C-H functionalized heteroarenes. © 2011 The Royal Society of Chemistry.

Journal	Data powered by TypesetChemistry - A European Journal
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ISSN	09476539
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