The reaction of an intermediate, generated from [Cp#MoCl 4] [Cp# = Cp or Cp; Cp = (η5-C 5H5), Cp= (η5-C5Me5)] and LiBH4.thf, with different chalcogen ligands yielded trimolybdaborane clusters 1-3, [(Cp#Mo)3(μ-H)B 8H6X2], (1: Cp# = Cp, X = H; 2: Cp# = Cp, X = H; 3: Cp# = Cp, X = Cl). Compounds 1-3 constitute an example of an unsaturated (n-4) sep cluster having very close structural similarities. These clusters represent 11-vertex boron-rich metallaboranes containing 66 cluster valence electrons (cve). All the compounds were fully characterized by various spectroscopic techniques, elemental analysis and the solid state structures were unequivocally established by X-ray diffraction analysis of 1-3. © 2012 Elsevier B.V. All rights reserved.

Sundargopal Ghosh

Department Of Chemistry

Bijan Mondal

Venkatachalam Ramkumar

boron

Chlorine compounds

Reaction intermediates

Spectroscopic analysis

X ray diffraction analysis

11-VERTEX METALLABORANE

Borane

Metallaboranes

Solid-state structures

Spectroscopic technique

Structural similarity

TRINUCLEARMOLYBDABORANES

VALENCE ELECTRON

Unsaturated compounds

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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

Journal of Organometallic Chemistry

A series of novel isocloso-diiridaboranes [(Cp∗Ir)2B6H6], 1, 2; [1,7-(Cp∗Ir)2B8H8], 4; [1,4-(Cp∗Ir)2B8H8], 5; [(Cp∗Ir)2B9H9], 8; isonido-[(Cp∗Ir)2B7H7], 3; and 10-vertex cluster [5,7-(Cp∗Ir)2B8H12], 6 (Cp∗ = η5-C5Me5) have been isolated and structurally characterized from the pyrolysis of [Cp∗IrCl2]2 and BH3·thf. On the other hand, the corresponding rhodium system afforded 10- and 11-vertices clusters [5-(Cp∗Rh)B9H13)], 7, and [(Cp∗Rh)2B9H9], 9, respectively. Clusters 1 and 2 are topological isomers. The geometry of 1 is dodecahedral, similar to that of its parent borane [B8H8]2-, in which two of the [BH] vertices are replaced by two [Cp∗Ir] fragments. The geometry of 2 can be derived from a nine-vertex tricapped trigonal prism by removing one of the capped vertices. Compounds 4 and 5 are 10-vertex isocloso clusters based on a 10-vertex bicapped square antiprism structure. The only difference between them is the presence of a metal-metal bond in 5. The solid-state structures of 8 and 9 attain an 11-vertex geometry in which a unique six-membered B6H6 moiety is bonded to the metal center. In addition, quantum-chemical calculations have been used to provide further insight into the electronic structure and stability of the clusters. All the compounds have been characterized by IR and 1H, 11B, and 13C NMR spectroscopy in solution, and the solid-state structures were established by X-ray crystallographic analysis. © 2016 American Chemical Society.

Inorganic Chemistry

Hypoelectronic 8-11-Vertex Irida- and Rhodaboranes

Reaction of [Cp*CoCl]2 (Cp* = η5-C5Me5) with [LiBH4· THF] in toluene at -70 C, followed by thermolysis with 2-mercaptobenzothiazole (C7H5NS2) in boiling toluene led to the isolation of a range of cobaltaborane clusters, [(Cp*Co) 2B7H6OMe], 1; [(Cp*Co) 3B8H7R], 2a, b (2a: R = H; 2b: R = Me); [(Cp*Co)3B8H8S], 3 and [(Cp*Co)2B4H4RR′], 4a-d (4a: R, R′ = H; 4b: R = Me, R′ = H; 4c: R = H, R′ = Me and 4d: R, R′ = Me). In parallel to the formation of compounds 1-4, the reaction also yielded known [(Cp*Co)3B4H 4] in good yield. Compound 1 may be considered as 9-vertex hypoelectronic cluster with C1 symmetry, where cobalt atoms occupy the degree 5 vertices. All the dicobaltaboranes 4a-d contains two μ3-H protons and found to be very reactive. As a result, one of them (4a) when reacted with Fe2(CO)9 and sulfur powder yielded, almost immediately, [(Cp*Co)2B 4H5SFe3(CO)9], 5 and [(Cp *Co)2B3H3(μ-CO)Fe(CO) 3], 6. All the new compounds have been characterized in solution by mass, 1H, 11B, 13C NMR spectroscopy and elemental analysis. The structural types were unequivocally established by X-ray crystallographic analysis of compounds 1-6. Density functional theory (DFT) calculations on the model compounds 1′ and 2′ (1′, and 2′ are the Cp analog of 1, and 2a respectively, Cp = C5H 5) yield geometries in agreement with the structure determinations. The existence of large HOMO-LUMO gap of these molecules rationalizes the isocloso description for 2a. Bonding patterns in the structure have been analyzed on the grounds of DFT calculations. © 2013 Elsevier B.V. All rights reserved.

Hypoelectronic metallaboranes: Synthesis, structural characterization and electronic structures of metal-rich cobaltaboranes

We have synthesized and structurally characterized several dimetallaheteroborane clusters, namely, nido-[(Cp*Mo)2B 4SH6], 1; nido-[(Cp*Mo)2B 4SeH6], 2; nido-[(Cp*Mo)2B 4TeClH5], 3; [(Cp*Mo)2B 5SeH7], 4; [(Cp*Mo)2B6SeH 8], 5; and [(CpW)2B5Te2H 5], 6 (Cp* = η5-C5Me5, Cp = η5-C5H5). In parallel to the formation of 1-6, known [(CpM)2B5H9], [(Cp*M) 2B5H9], (M = Mo, W) and nido-[(Cp*M) 2B4E2H4] compounds (when M = Mo; E = S, Se, Te; M = W, E = S) were isolated as major products. Cluster 6 is the first example of tungstaborane containing a heavier chalcogen (Te) atom. A combined theoretical and experimental study shows that clusters 1-3 with their open face are excellent precursors for cluster growth reactions. As a result, the reaction of 1 and 2 with [Co2(CO)8] yielded clusters [(Cp*Mo)2B4H4E(μ3-CO) Co2(CO)4], 7-8 (7: E = S, 8: E = Se) and [(Cp*Mo)2B3H3E(μ-CO) 3Co2(CO)3], 9-10 (9: E = S, 10: E = Se). In contrast, compound 3 under the similar reaction conditions yielded a novel 24-valence electron triple-decker sandwich complex, [(Cp*Mo) 2{μ-η6:η6-B3H 3TeCo2(CO)5}], 11. Cluster 11 represents an unprecedented metal sandwich cluster in which the middle deck is composed of B, Co, and Te. All the new compounds have been characterized by elemental analysis, IR, 1H, 11B, 13C NMR spectroscopy, and the geometric structures were unequivocally established by X-ray diffraction analysis of 1, 2, 4-7, and 9-11. Furthermore, geometries obtained from the electronic structure calculations employing density functional theory (DFT) are in close agreement with the solid state structure determinations. We have analyzed the discrepancy in reactivity of the chalcogenato metallaborane clusters in comparison to their parent metallaboranes with the help of a density functional theory (DFT) study. © 2013 American Chemical Society.

Hypoelectronic dimetallaheteroboranes of group 6 transition metals containing heavier chalcogen elements

Chemistry and reactivity of dimolybdathiaborane, [(Cp*Mo) 2B2SH2], 1, obtained from the reaction of 2-mercaptobenzothiazole, [Cp*MoCl2] and [LiBH2.thf], has been explored with dinuclear metal carbonyl [Fe2(CO) 2]. As a result, reaction of 1 with [Fe2(CO)2] yielded heterometallathiaborane, [(Cp*Mo)2B2H 2SFe(CO)2], 2 in good yield. Both the new compounds have been characterized in solution by 1H, 11B and 13C NMR spectroscopy and the structural types were unequivocally established by X-ray crystallographic analysis of compound 2. Cluster 2 has a bicapped octahedral geometry with the {Fe(CO)3} fragment occupying one of the high-connectivity cluster vertexes rather than a capping position. Interestingly, cluster 1 undergoes geometric changes (bicapped trigonal bipyramid → bicapped octahedron) on the addition of two-electron {Fe(CO)3} fragment to 1. © Indian Academy of Sciences.

Fulltext

Journal of Chemical Sciences

Synthesis and reactivity of dimolybdathiaborane cluster [(Cp*Mo) 2B2SH2] (Cp* = η5-C 2Me2)

Reaction of (η5-C5Me5)MoCl4 with 6-fold excess of LiBH4·thf followed by pyrolysis with BHCl2·SMe2 in toluene at 90 °C yielded known (η5-C5Me5Mo)2B5H9 (1) and B-Cl inserted (η5-C5Me5Mo)2B5H8Cl (2), (η5-C5Me5Mo)2B5H7Cl2 (3-5, three isomers) and (η5-C5Me5Mo)2B5H5Cl4 (6). In addition, reaction of (η5-C5Me5Mo)2B5H9 with 5-fold excess of n-BuLi followed by excess of MeI in THF yielded B-Me inserted metallaboranes (η5-C5Me5Mo)2B5H7(CH3)2 (7, 8 two isomers) and (η5-C5Me5Mo)2B5H6(CH3)3 (9, 10 two isomers). Isolated yields of 2-6 are poor but 7-10 are modest to good. Compounds 2-10 can be viewed as bicapped closo trigonal bipyramidal geometry. All the new compounds have been characterized in solution by IR, 1H, 11B, 13C NMR and mass spectroscopy as simple substitution derivatives of (η5-C5Me5Mo)2B5H9 and the structural types were unequivocally established by crystallographic analysis of compounds 2, 3, 5 and 6. © 2008 Elsevier B.V. All rights reserved.

Substitution at boron in molybdaborane frameworks: Synthesis and characterization of isomeric (η5-C5Me5Mo)2B5HnXm (when X = Cl: n = 5, 7, 8; m = 4, 2, 1 and X = Me: n = 6, 7; m = 3, 2)

Dalton Transactions

Chemistry of 11-vertex rhodathiaboranes: reactions with monodentate phosphines

Reaction of [(η5-C5Me5)MCl4], 1-2 (1: M = Mo and 2: W) with six fold excess of [LiBH4·thf] followed by thermolysis with excess chalcogen powders (S, Se and Te) yielded dichalcomolybda- and tungstaboranes, [(η5-C5Me5M)2B4H4E2], 5-8 (5: M = Mo, E = S; 6: M = Mo, E = Se; 7: M = Mo, E = Te; 8: M = W, E = Se) in modest yields. The geometry of 5-8 resembles a hexagonal bipyramid with a missing connectivity of two chalcogen vertices and a very short cross cage metal-metal bonding. All these new dichalcometallaboranes have been characterized by mass, 1H, 11B, 13C NMR spectroscopy, and the structural types were unequivocally established by crystallographic analysis of compound 6. © 2009 Elsevier B.V. All rights reserved.

Direct insertion of sulfur, selenium and tellurium atoms into metallaborane cages using chalcogen powders

The reaction of the [(η5-C5Me5) MoCl4] complex with [LiBH4·THF] in toluene at -70 °C, followed by pyrolysis at 110 °C, afforded dark brown [(η5-C5Me5Mo)3MoB 9H18], 2, in parallel with the known [(η5- C5Me5Mo)2B5H9], 1. Compound 2 has been characterized in solution by 1H, 11B, and 10C NMR spectroscopy and elemental analysis, and the structural types were unequivocally established by crystallographic studies. The title compound represents a novel class of vertex-fused clusters in which a Mo atom has been fused in a perpendicular fashion between two molybdaborane clusters. Electronic structure calculations employing density functional theory yield geometries in agreement with the structure determinations, and on grounds of density functional theory calculations, we have analyzed the bonding patterns in the structure . © 2010 American Chemical Society.

Journal	Data powered by TypesetJournal of Organometallic Chemistry
Publisher	Data powered by TypesetElsevier B.V.
ISSN	0022328X
Open Access	No