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.

Sundargopal Ghosh

Department Of Chemistry

Koushik Saha

Urminder Kaur

Sourav Kar

Bijan Mondal

Benson Joseph

P. K.Sudhadevi Antharjanam

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Inorganic Chemistry

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 room-temperature reaction of [Cp*TaCl4] with LiBH4⋅THF followed by addition of S2CPPh3 results in pentahydridodiborate species [(Cp*Ta)2(μ,η2:η2-B2H5)(μ-H)(κ2,μ-S2CH2)2] (1), a classical [B2H5]− ion stabilized by the binuclear tantalum template. Theoretical studies and bonding analysis established that the unusual stability of [B2H5]− in 1 is mainly due to the stabilization of sp2-B center by electron donation from tantalum. Reactions to replace the hydrogens attached to the diborane moiety in 1 with a 2 e {M(CO)4} fragment (M=Mo or W) resulted in simple adducts, [{(Cp*Ta)(CH2S2)}2(B2H5)(H){M(CO)3}] (6: M=Mo and 7: M=W), that retained the diborane(5) unit. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Angewandte Chemie - International Edition

Stabilization of Classical [B2H5]−: Structure and Bonding of [(Cp*Ta)2(B2H5)(μ-H)L2] (Cp*=η5-C5Me5; L=SCH2S)

A series of hydroborated η4-σ,π-alkene-borane complexes have been synthesized from the reaction of ruthenium-bis(σ)borate complex [Cp∗Ru(μ-H)2BH(S-CH=S)] (1) and terminal as well as internal alkynes. Likewise, the reactions of manganese-bis(σ)borate complexes [Mn(CO)3(μ-H)2BHNCSC6H4(NL)] (L = NCSC6H4 or H) were explored with terminal alkynes that yielded boratabutadiene complexes [Mn(CO)3{(NCSC6H4)2N}{(R1MeC)=B(HC=CHR1)}] [R1 = phenyl (4a) or p-tolyl (4b)] via triple hydroboration of alkynes. These complexes feature a boratabutadiene ligand that is coordinated to a metal through the η4-CBCC mode. To the best of our knowledge, these are the first examples of η4-E-boratabutadiene-coordinated manganese complexes generated by the trans-hydroboration of alkynes. The steric and electronic effects of the borate ligands have been demonstrated using a less sterically hindered manganese-bis(σ)borate complex, [Mn(CO)3(μ-H)2BH(HN2CSC6H4)], that generated monohydroborated complexes [(CO)3Mn(μ-H)2(HN2CSC6H4)B(R1C=CHR2)] (for 6, R1 = Ph and R2 = H; for 7, R1 = p-Tol and R2 = H; for 8, R1 = R2 = Ph). Theoretical studies using density functional theory methods and chemical bonding analyses established the bonding and stability of these species. © 2019 American Chemical Society.

Hydroboration of Alkynes: η4-Alkene-Borane versus η4- E-Boratabutadiene

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.

Chemistry - A European Journal

New Routes to a Series of σ-Borane/Borate Complexes of Molybdenum and Ruthenium

Reactions of the CS2 and CO2 heterocumulene ligands with nido-ruthenaborane cluster [1,2-(Cp∗Ru)2(μ-H)2B3H7], 1, were explored (Cp∗ = pentamethylcyclopentadienyl). Compound 1 when treated with CS2 underwent metal-assisted hydroboration to yield arachno-ruthenaborane [(Cp∗Ru)2(B3H8)(CS2H)], 2, with a dithioformato ligand attached to it. The chemistry of 2 was then explored with various transition metal carbonyl compounds under photolytic and thermolytic conditions. Thermolysis of 2 with [Mn2(CO)10] resulted in the formation of an unprecedented cubane-type cluster [(Cp∗Ru)2Mn(CO)3(CS2H2)B3H4], 3, with a rare [M3E5] formulation (E = B, S). On the other hand, when compound 2 was photolyzed in the presence of [Mn2(CO)10], it yielded an incomplete cubane-type cluster [(Cp∗Ru)2Mn(CO)3BH2(CS2H2)], 4. The room-temperature reaction of 2 with [Fe2(CO)9] yielded heterometallic arachno clusters [(Cp∗Ru)(CO)2{Fe(CO)3}2S2CH3], 6 and [(Cp∗Ru)2(B3H8)(CO){Fe(CO)3}2(CS2H)], 7. In contrast, photolysis of 2 with [Fe2(CO)9] yielded a tetrahedral cluster [(Cp∗Ru)(CO)2S(μ-H){Fe(CO)3}3], 8, tethered to an exo-polyhedral moiety [(Cp∗Ru)(CO)2]. Compound 6 provides an unusual bonding pattern by means of fusing the wing-tip vertex (S) of the [Fe2S2] butterfly core by an exo-polyhedral [(Cp∗Ru)(CO)2] unit. Density functional theory calculations were carried out to provide insight into the mechanistic pathway, electronic structure, and bonding properties. © 2014 American Chemical Society.

Chemistry of diruthenium analogue of pentaborane(9) with heterocumulenes: Toward novel trimetallic cubane-type clusters

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)

Room temperature photolysis of a triply-bridged borylene complex, [(μ3-BH)(Cp*RuCO)2(μ-CO)Fe(CO)3] (1 a; Cp*=C5Me5), in the presence of a series of alkynes, 1,2-diphenylethyne, 1-phenyl-1-propyne, and 2-butyne led to the isolation of unprecedented vinyl-borylene complexes (Z)-[(Cp*RuCO) 2(μ-CO)B(CR)(CHR′)] (2: R, R′=Ph; 3: R=Me, R′=Ph; 4: R, R′=Me). This reaction permits a hydroboration of alkyne through an anti-Markovnikov addition. In stark contrast, in the presence of phenylacetylene, a metallacarborane, closo-[1,2-(Cp*Ru) 2(μ-CO)2{Fe2(CO)5}-4-Ph-4,5- C2BH2] (5 a), is formed. A plausible mechanism has been proposed for the formation of vinyl-borylene complexes, which is supported by density functional theory (DFT) methods. Furthermore, the calculated 11B NMR chemical shifts accurately reflect the experimentally measured shifts. All the new compounds have been characterized in solution by mass spectrometry and IR, 1H, 11B, and 13C NMR spectroscopies and the structural types were unequivocally established by crystallographic analysis of 2, 5 a, and 5 b. Unique metal-borylene complexes: Photolysis of a triply bridged borylene complex [(μ3-BH) (Cp*RuCO)2(μ-CO)Fe(CO)3] (Cp*= η5-C5Me5) with various internal alkynes led to hydroboration yielding new vinyl-borylene complexes (see figure). A plausible mechanism has been proposed for the formation of vinyl-borylene complexes, which is supported by density functional theory (DFT) methods. Copyright © 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Syntheses and characterization of new vinyl-borylene complexes by the hydroboration of alkynes with [(μ3-BH)(Cp*RuCO) 2(μ-CO)Fe(CO)3]

Syntheses and structural characterization of supraicosahedral rhodaborane clusters are reported. Reaction of [(Cp*RhCl2)2], (Cp* = η5-C5Me5) with [LiBH 4·thf] followed by thermolysis with excess of [BH 3·thf] afforded 16-vertex closo-[(Cp*Rh) 3B12H12Rh{Cp*RhB4H 9}], 1, 15-vertex [(Cp*Rh)2B13H 13], 2, 12-vertex [(Cp*Rh)2B10H n(OH)m], (3a: n = 12, m = 0; 3b: n = 9, m = 1; 3c: n = 8, m = 2) and 10-vertex [(Cp*Rh)3B7H7], 4, and [(Cp*Rh)4B6H6], 5. Cluster 1 is the unprecedented 16-vertex cluster, consists of a sixteen-vertex {Rh 4B12} with an exo-polyhedral {RhB4} moiety. Cluster 2 is the first example of a carbon free 15-vertex supraicosahedral metallaborane, exhibits icosihexahedron geometry (26 triangular faces) with three degree-six vertices. Clusters 3a-c have 12-vertex isocloso geometry, different from that of icosahedral one. Clusters 4 and 5 are attributed to the 10-vertex isocloso geometry based on 10-vertex bicapped square antiprism structure. In addition, quantum-chemical calculations with DFT methods at the BP86 level of theory have been used to provide further insight into the electronic structure and stability of the optimized structures which are in satisfactory agreement with the structure determinations. All the compounds have been characterized by IR, 1H, 11B, 13C NMR spectroscopy in solution, and the solid state structures were established by crystallographic analysis of compounds 1-5. © 2013 American Chemical Society.

Journal	Data powered by TypesetInorganic Chemistry
Publisher	Data powered by TypesetAmerican Chemical Society
ISSN	00201669
Open Access	No